2 /* pngvalid.c - validate libpng by constructing then reading png files.
4 * Last changed in libpng 1.7.0 [(PENDING RELEASE)]
5 * Copyright (c) 2014 Glenn Randers-Pehrson
6 * Written by John Cunningham Bowler
8 * This code is released under the libpng license.
9 * For conditions of distribution and use, see the disclaimer
10 * and license in png.h
13 * This is a C program that is intended to be linked against libpng. It
14 * generates bitmaps internally, stores them as PNG files (using the
15 * sequential write code) then reads them back (using the sequential
16 * read code) and validates that the result has the correct data.
18 * The program can be modified and extended to test the correctness of
19 * transformations performed by libpng.
22 #define _POSIX_SOURCE 1
23 #define _ISOC99_SOURCE 1 /* For floating point */
24 #define _GNU_SOURCE 1 /* For the floating point exception extension */
29 #if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
33 #ifdef HAVE_FEENABLEEXCEPT /* from config.h, if included */
37 /* Define the following to use this test against your installed libpng, rather
38 * than the one being built here:
40 #ifdef PNG_FREESTANDING_TESTS
43 # include "../../png.h"
46 #ifdef PNG_ZLIB_HEADER
47 # include PNG_ZLIB_HEADER
49 # include <zlib.h> /* For crc32 */
52 /* 1.6.1 added support for the configure test harness, which uses 77 to indicate
53 * a skipped test, in earlier versions we need to succeed on a skipped test, so:
55 #if PNG_LIBPNG_VER < 10601
61 /* pngvalid requires write support and one of the fixed or floating point APIs.
63 #if defined(PNG_WRITE_SUPPORTED) &&\
64 (defined(PNG_FIXED_POINT_SUPPORTED) || defined(PNG_FLOATING_POINT_SUPPORTED))
66 #if PNG_LIBPNG_VER < 10500
67 /* This deliberately lacks the PNG_CONST. */
68 typedef png_byte *png_const_bytep;
70 /* This is copied from 1.5.1 png.h: */
71 #define PNG_INTERLACE_ADAM7_PASSES 7
72 #define PNG_PASS_START_ROW(pass) (((1U&~(pass))<<(3-((pass)>>1)))&7)
73 #define PNG_PASS_START_COL(pass) (((1U& (pass))<<(3-(((pass)+1)>>1)))&7)
74 #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
75 #define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
76 #define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
77 -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
78 #define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
79 -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
80 #define PNG_ROW_FROM_PASS_ROW(yIn, pass) \
81 (((yIn)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
82 #define PNG_COL_FROM_PASS_COL(xIn, pass) \
83 (((xIn)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
84 #define PNG_PASS_MASK(pass,off) ( \
85 ((0x110145AFU>>(((7-(off))-(pass))<<2)) & 0xFU) | \
86 ((0x01145AF0U>>(((7-(off))-(pass))<<2)) & 0xF0U))
87 #define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
88 ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
89 #define PNG_COL_IN_INTERLACE_PASS(x, pass) \
90 ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
92 /* These are needed too for the default build: */
93 #define PNG_WRITE_16BIT_SUPPORTED
94 #define PNG_READ_16BIT_SUPPORTED
96 /* This comes from pnglibconf.h afer 1.5: */
97 #define PNG_FP_1 100000
98 #define PNG_GAMMA_THRESHOLD_FIXED\
99 ((png_fixed_point)(PNG_GAMMA_THRESHOLD * PNG_FP_1))
102 #if PNG_LIBPNG_VER < 10600
103 /* 1.6.0 constifies many APIs, the following exists to allow pngvalid to be
104 * compiled against earlier versions.
106 # define png_const_structp png_structp
109 #include <float.h> /* For floating point constants */
110 #include <stdlib.h> /* For malloc */
111 #include <string.h> /* For memcpy, memset */
112 #include <math.h> /* For floor */
114 /* Unused formal parameter errors are removed using the following macro which is
115 * expected to have no bad effects on performance.
118 # if defined(__GNUC__) || defined(_MSC_VER)
119 # define UNUSED(param) (void)param;
121 # define UNUSED(param)
125 /* Fixups for various minimal builds */
126 #ifndef PNG_ERROR_TEXT_SUPPORTED
127 # define png_error(a,b) png_err(a)
130 /***************************** EXCEPTION HANDLING *****************************/
131 #ifdef PNG_FREESTANDING_TESTS
132 # include <cexcept.h>
134 # include "../visupng/cexcept.h"
138 # define this not_the_cpp_this
139 # define new not_the_cpp_new
140 # define voidcast(type, value) static_cast<type>(value)
142 # define voidcast(type, value) (value)
143 #endif /* __cplusplus */
146 define_exception_type(struct png_store*);
148 /* The following are macros to reduce typing everywhere where the well known
149 * name 'the_exception_context' must be defined.
151 #define anon_context(ps) struct exception_context *the_exception_context = \
152 &(ps)->exception_context
153 #define context(ps,fault) anon_context(ps); png_store *fault
155 /******************************* UTILITIES ************************************/
156 /* Error handling is particularly problematic in production code - error
157 * handlers often themselves have bugs which lead to programs that detect
158 * minor errors crashing. The following functions deal with one very
159 * common class of errors in error handlers - attempting to format error or
160 * warning messages into buffers that are too small.
162 static size_t safecat(char *buffer, size_t bufsize, size_t pos,
165 while (pos < bufsize && cat != NULL && *cat != 0)
166 buffer[pos++] = *cat++;
175 static size_t safecatn(char *buffer, size_t bufsize, size_t pos, int n)
178 sprintf(number, "%d", n);
179 return safecat(buffer, bufsize, pos, number);
182 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
183 static size_t safecatd(char *buffer, size_t bufsize, size_t pos, double d,
187 sprintf(number, "%.*f", precision, d);
188 return safecat(buffer, bufsize, pos, number);
192 static PNG_CONST char invalid[] = "invalid";
193 static PNG_CONST char sep[] = ": ";
195 static PNG_CONST char *colour_types[8] =
197 "grayscale", invalid, "truecolour", "indexed-colour",
198 "grayscale with alpha", invalid, "truecolour with alpha", invalid
201 #ifdef PNG_READ_SUPPORTED
202 /* Convert a double precision value to fixed point. */
203 static png_fixed_point
206 d = floor(d * PNG_FP_1 + .5);
207 return (png_fixed_point)d;
209 #endif /* PNG_READ_SUPPORTED */
211 /* Generate random bytes. This uses a boring repeatable algorithm and it
212 * is implemented here so that it gives the same set of numbers on every
213 * architecture. It's a linear congruential generator (Knuth or Sedgewick
214 * "Algorithms") but it comes from the 'feedback taps' table in Horowitz and
215 * Hill, "The Art of Electronics" (Pseudo-Random Bit Sequences and Noise
219 make_random_bytes(png_uint_32* seed, void* pv, size_t size)
221 png_uint_32 u0 = seed[0], u1 = seed[1];
222 png_bytep bytes = voidcast(png_bytep, pv);
224 /* There are thirty three bits, the next bit in the sequence is bit-33 XOR
225 * bit-20. The top 1 bit is in u1, the bottom 32 are in u0.
228 for (i=0; i<size; ++i)
230 /* First generate 8 new bits then shift them in at the end. */
231 png_uint_32 u = ((u0 >> (20-8)) ^ ((u1 << 7) | (u0 >> (32-7)))) & 0xff;
236 *bytes++ = (png_byte)u;
244 make_four_random_bytes(png_uint_32* seed, png_bytep bytes)
246 make_random_bytes(seed, bytes, 4);
249 #ifdef PNG_READ_SUPPORTED
251 randomize(void *pv, size_t size)
253 static png_uint_32 random_seed[2] = {0x56789abc, 0xd};
254 make_random_bytes(random_seed, pv, size);
257 #define RANDOMIZE(this) randomize(&(this), sizeof (this))
260 random_mod(unsigned int max)
266 return x % max; /* 0 .. max-1 */
269 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
280 #endif /* PNG_READ_SUPPORTED */
282 /* A numeric ID based on PNG file characteristics. The 'do_interlace' field
283 * simply records whether pngvalid did the interlace itself or whether it
284 * was done by libpng. Width and height must be less than 256. 'palette' is an
285 * index of the palette to use for formats with a palette (0 otherwise.)
287 #define FILEID(col, depth, palette, interlace, width, height, do_interlace) \
288 ((png_uint_32)((col) + ((depth)<<3) + ((palette)<<8) + ((interlace)<<13) + \
289 (((do_interlace)!=0)<<15) + ((width)<<16) + ((height)<<24)))
291 #define COL_FROM_ID(id) ((png_byte)((id)& 0x7U))
292 #define DEPTH_FROM_ID(id) ((png_byte)(((id) >> 3) & 0x1fU))
293 #define PALETTE_FROM_ID(id) (((id) >> 8) & 0x1f)
294 #define INTERLACE_FROM_ID(id) ((int)(((id) >> 13) & 0x3))
295 #define DO_INTERLACE_FROM_ID(id) ((int)(((id)>>15) & 1))
296 #define WIDTH_FROM_ID(id) (((id)>>16) & 0xff)
297 #define HEIGHT_FROM_ID(id) (((id)>>24) & 0xff)
299 /* Utility to construct a standard name for a standard image. */
301 standard_name(char *buffer, size_t bufsize, size_t pos, png_byte colour_type,
302 int bit_depth, unsigned int npalette, int interlace_type,
303 png_uint_32 w, png_uint_32 h, int do_interlace)
305 pos = safecat(buffer, bufsize, pos, colour_types[colour_type]);
308 pos = safecat(buffer, bufsize, pos, "[");
309 pos = safecatn(buffer, bufsize, pos, npalette);
310 pos = safecat(buffer, bufsize, pos, "]");
312 pos = safecat(buffer, bufsize, pos, " ");
313 pos = safecatn(buffer, bufsize, pos, bit_depth);
314 pos = safecat(buffer, bufsize, pos, " bit");
316 if (interlace_type != PNG_INTERLACE_NONE)
318 pos = safecat(buffer, bufsize, pos, " interlaced");
320 pos = safecat(buffer, bufsize, pos, "(pngvalid)");
322 pos = safecat(buffer, bufsize, pos, "(libpng)");
327 pos = safecat(buffer, bufsize, pos, " ");
328 pos = safecatn(buffer, bufsize, pos, w);
329 pos = safecat(buffer, bufsize, pos, "x");
330 pos = safecatn(buffer, bufsize, pos, h);
337 standard_name_from_id(char *buffer, size_t bufsize, size_t pos, png_uint_32 id)
339 return standard_name(buffer, bufsize, pos, COL_FROM_ID(id),
340 DEPTH_FROM_ID(id), PALETTE_FROM_ID(id), INTERLACE_FROM_ID(id),
341 WIDTH_FROM_ID(id), HEIGHT_FROM_ID(id), DO_INTERLACE_FROM_ID(id));
344 /* Convenience API and defines to list valid formats. Note that 16 bit read and
345 * write support is required to do 16 bit read tests (we must be able to make a
346 * 16 bit image to test!)
348 #ifdef PNG_WRITE_16BIT_SUPPORTED
349 # define WRITE_BDHI 4
350 # ifdef PNG_READ_16BIT_SUPPORTED
355 # define WRITE_BDHI 3
361 /* The following defines the number of different palettes to generate for
362 * each log bit depth of a colour type 3 standard image.
364 #define PALETTE_COUNT(bit_depth) ((bit_depth) > 4 ? 1U : 16U)
367 next_format(png_bytep colour_type, png_bytep bit_depth,
368 unsigned int* palette_number, int no_low_depth_gray)
373 if (no_low_depth_gray)
381 if (*colour_type == 3)
383 /* Add multiple palettes for colour type 3. */
384 if (++*palette_number < PALETTE_COUNT(*bit_depth))
390 *bit_depth = (png_byte)(*bit_depth << 1);
392 /* Palette images are restricted to 8 bit depth */
395 || (*colour_type != 3 && *bit_depth <= 16)
400 /* Move to the next color type, or return 0 at the end. */
401 switch (*colour_type)
428 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
430 sample(png_const_bytep row, png_byte colour_type, png_byte bit_depth,
431 png_uint_32 x, unsigned int sample_index)
433 png_uint_32 bit_index, result;
435 /* Find a sample index for the desired sample: */
439 if ((colour_type & 1) == 0) /* !palette */
445 bit_index += x; /* Alpha channel */
447 /* Multiple channels; select one: */
448 if (colour_type & (2+4))
449 bit_index += sample_index * bit_depth;
452 /* Return the sample from the row as an integer. */
453 row += bit_index >> 3;
459 else if (bit_depth > 8)
460 return (result << 8) + *++row;
462 /* Less than 8 bits per sample. */
464 return (result >> (8-bit_index-bit_depth)) & ((1U<<bit_depth)-1);
466 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
468 /* Copy a single pixel, of a given size, from one buffer to another -
469 * while this is basically bit addressed there is an implicit assumption
470 * that pixels 8 or more bits in size are byte aligned and that pixels
471 * do not otherwise cross byte boundaries. (This is, so far as I know,
472 * universally true in bitmap computer graphics. [JCB 20101212])
474 * NOTE: The to and from buffers may be the same.
477 pixel_copy(png_bytep toBuffer, png_uint_32 toIndex,
478 png_const_bytep fromBuffer, png_uint_32 fromIndex, unsigned int pixelSize)
480 /* Assume we can multiply by 'size' without overflow because we are
481 * just working in a single buffer.
483 toIndex *= pixelSize;
484 fromIndex *= pixelSize;
485 if (pixelSize < 8) /* Sub-byte */
487 /* Mask to select the location of the copied pixel: */
488 unsigned int destMask = ((1U<<pixelSize)-1) << (8-pixelSize-(toIndex&7));
489 /* The following read the entire pixels and clears the extra: */
490 unsigned int destByte = toBuffer[toIndex >> 3] & ~destMask;
491 unsigned int sourceByte = fromBuffer[fromIndex >> 3];
493 /* Don't rely on << or >> supporting '0' here, just in case: */
495 if (fromIndex > 0) sourceByte <<= fromIndex;
496 if ((toIndex & 7) > 0) sourceByte >>= toIndex & 7;
498 toBuffer[toIndex >> 3] = (png_byte)(destByte | (sourceByte & destMask));
500 else /* One or more bytes */
501 memmove(toBuffer+(toIndex>>3), fromBuffer+(fromIndex>>3), pixelSize>>3);
504 #ifdef PNG_READ_SUPPORTED
505 /* Copy a complete row of pixels, taking into account potential partial
509 row_copy(png_bytep toBuffer, png_const_bytep fromBuffer, unsigned int bitWidth)
511 memcpy(toBuffer, fromBuffer, bitWidth >> 3);
513 if ((bitWidth & 7) != 0)
517 toBuffer += bitWidth >> 3;
518 fromBuffer += bitWidth >> 3;
519 /* The remaining bits are in the top of the byte, the mask is the bits to
522 mask = 0xff >> (bitWidth & 7);
523 *toBuffer = (png_byte)((*toBuffer & mask) | (*fromBuffer & ~mask));
527 /* Compare pixels - they are assumed to start at the first byte in the
531 pixel_cmp(png_const_bytep pa, png_const_bytep pb, png_uint_32 bit_width)
533 #if PNG_LIBPNG_VER < 10506
534 if (memcmp(pa, pb, bit_width>>3) == 0)
538 if ((bit_width & 7) == 0) return 0;
540 /* Ok, any differences? */
541 p = pa[bit_width >> 3];
542 p ^= pb[bit_width >> 3];
544 if (p == 0) return 0;
546 /* There are, but they may not be significant, remove the bits
547 * after the end (the low order bits in PNG.)
552 if (p == 0) return 0;
555 /* From libpng-1.5.6 the overwrite should be fixed, so compare the trailing
558 if (memcmp(pa, pb, (bit_width+7)>>3) == 0)
562 /* Return the index of the changed byte. */
564 png_uint_32 where = 0;
566 while (pa[where] == pb[where]) ++where;
570 #endif /* PNG_READ_SUPPORTED */
572 /*************************** BASIC PNG FILE WRITING ***************************/
573 /* A png_store takes data from the sequential writer or provides data
574 * to the sequential reader. It can also store the result of a PNG
575 * write for later retrieval.
577 #define STORE_BUFFER_SIZE 500 /* arbitrary */
578 typedef struct png_store_buffer
580 struct png_store_buffer* prev; /* NOTE: stored in reverse order */
581 png_byte buffer[STORE_BUFFER_SIZE];
584 #define FILE_NAME_SIZE 64
586 typedef struct store_palette_entry /* record of a single palette entry */
592 } store_palette_entry, store_palette[256];
594 typedef struct png_store_file
596 struct png_store_file* next; /* as many as you like... */
597 char name[FILE_NAME_SIZE];
598 png_uint_32 id; /* must be correct (see FILEID) */
599 png_size_t datacount; /* In this (the last) buffer */
600 png_store_buffer data; /* Last buffer in file */
601 int npalette; /* Number of entries in palette */
602 store_palette_entry* palette; /* May be NULL */
605 /* The following is a pool of memory allocated by a single libpng read or write
608 typedef struct store_pool
610 struct png_store *store; /* Back pointer */
611 struct store_memory *list; /* List of allocated memory */
612 png_byte mark[4]; /* Before and after data */
614 /* Statistics for this run. */
615 png_alloc_size_t max; /* Maximum single allocation */
616 png_alloc_size_t current; /* Current allocation */
617 png_alloc_size_t limit; /* Highest current allocation */
618 png_alloc_size_t total; /* Total allocation */
620 /* Overall statistics (retained across successive runs). */
621 png_alloc_size_t max_max;
622 png_alloc_size_t max_limit;
623 png_alloc_size_t max_total;
626 typedef struct png_store
628 /* For cexcept.h exception handling - simply store one of these;
629 * the context is a self pointer but it may point to a different
630 * png_store (in fact it never does in this program.)
632 struct exception_context
635 unsigned int verbose :1;
636 unsigned int treat_warnings_as_errors :1;
637 unsigned int expect_error :1;
638 unsigned int expect_warning :1;
639 unsigned int saw_warning :1;
640 unsigned int speed :1;
641 unsigned int progressive :1; /* use progressive read */
642 unsigned int validated :1; /* used as a temporary flag */
645 int noptions; /* number of options below: */
647 unsigned char option; /* option number, 0..30 */
648 unsigned char setting; /* setting (unset,invalid,on,off) */
650 char test[128]; /* Name of test */
654 png_structp pread; /* Used to read a saved file */
656 png_store_file* current; /* Set when reading */
657 png_store_buffer* next; /* Set when reading */
658 png_size_t readpos; /* Position in *next */
659 png_byte* image; /* Buffer for reading interlaced images */
660 png_size_t cb_image; /* Size of this buffer */
661 png_size_t cb_row; /* Row size of the image(s) */
662 png_uint_32 image_h; /* Number of rows in a single image */
663 store_pool read_memory_pool;
666 png_store_file* saved;
667 png_structp pwrite; /* Used when writing a new file */
669 png_size_t writepos; /* Position in .new */
670 char wname[FILE_NAME_SIZE];
671 png_store_buffer new; /* The end of the new PNG file being written. */
672 store_pool write_memory_pool;
673 store_palette_entry* palette;
677 /* Initialization and cleanup */
679 store_pool_mark(png_bytep mark)
681 static png_uint_32 store_seed[2] = { 0x12345678, 1};
683 make_four_random_bytes(store_seed, mark);
686 #ifdef PNG_READ_SUPPORTED
687 /* Use this for random 32 bit values; this function makes sure the result is
699 store_pool_mark(mark);
700 result = png_get_uint_32(mark);
706 #endif /* PNG_READ_SUPPORTED */
709 store_pool_init(png_store *ps, store_pool *pool)
711 memset(pool, 0, sizeof *pool);
715 pool->max = pool->current = pool->limit = pool->total = 0;
716 pool->max_max = pool->max_limit = pool->max_total = 0;
717 store_pool_mark(pool->mark);
721 store_init(png_store* ps)
723 memset(ps, 0, sizeof *ps);
724 init_exception_context(&ps->exception_context);
725 store_pool_init(ps, &ps->read_memory_pool);
726 store_pool_init(ps, &ps->write_memory_pool);
728 ps->treat_warnings_as_errors = 0;
729 ps->expect_error = 0;
730 ps->expect_warning = 0;
735 ps->nerrors = ps->nwarnings = 0;
738 ps->saved = ps->current = NULL;
755 store_freebuffer(png_store_buffer* psb)
759 store_freebuffer(psb->prev);
766 store_freenew(png_store *ps)
768 store_freebuffer(&ps->new);
770 if (ps->palette != NULL)
779 store_storenew(png_store *ps)
781 png_store_buffer *pb;
783 if (ps->writepos != STORE_BUFFER_SIZE)
784 png_error(ps->pwrite, "invalid store call");
786 pb = voidcast(png_store_buffer*, malloc(sizeof *pb));
789 png_error(ps->pwrite, "store new: OOM");
797 store_freefile(png_store_file **ppf)
801 store_freefile(&(*ppf)->next);
803 store_freebuffer(&(*ppf)->data);
804 (*ppf)->datacount = 0;
805 if ((*ppf)->palette != NULL)
807 free((*ppf)->palette);
808 (*ppf)->palette = NULL;
809 (*ppf)->npalette = 0;
816 /* Main interface to file storeage, after writing a new PNG file (see the API
817 * below) call store_storefile to store the result with the given name and id.
820 store_storefile(png_store *ps, png_uint_32 id)
822 png_store_file *pf = voidcast(png_store_file*, malloc(sizeof *pf));
824 png_error(ps->pwrite, "storefile: OOM");
825 safecat(pf->name, sizeof pf->name, 0, ps->wname);
828 pf->datacount = ps->writepos;
831 pf->palette = ps->palette;
832 pf->npalette = ps->npalette;
837 pf->next = ps->saved;
841 /* Generate an error message (in the given buffer) */
843 store_message(png_store *ps, png_const_structp pp, char *buffer, size_t bufsize,
844 size_t pos, PNG_CONST char *msg)
846 if (pp != NULL && pp == ps->pread)
849 pos = safecat(buffer, bufsize, pos, "read: ");
851 if (ps->current != NULL)
853 pos = safecat(buffer, bufsize, pos, ps->current->name);
854 pos = safecat(buffer, bufsize, pos, sep);
858 else if (pp != NULL && pp == ps->pwrite)
861 pos = safecat(buffer, bufsize, pos, "write: ");
862 pos = safecat(buffer, bufsize, pos, ps->wname);
863 pos = safecat(buffer, bufsize, pos, sep);
868 /* Neither reading nor writing (or a memory error in struct delete) */
869 pos = safecat(buffer, bufsize, pos, "pngvalid: ");
872 if (ps->test[0] != 0)
874 pos = safecat(buffer, bufsize, pos, ps->test);
875 pos = safecat(buffer, bufsize, pos, sep);
877 pos = safecat(buffer, bufsize, pos, msg);
881 /* Verbose output to the error stream: */
883 store_verbose(png_store *ps, png_const_structp pp, png_const_charp prefix,
884 png_const_charp message)
889 fputs(prefix, stderr);
891 (void)store_message(ps, pp, buffer, sizeof buffer, 0, message);
892 fputs(buffer, stderr);
896 /* Log an error or warning - the relevant count is always incremented. */
898 store_log(png_store* ps, png_const_structp pp, png_const_charp message,
901 /* The warning is copied to the error buffer if there are no errors and it is
902 * the first warning. The error is copied to the error buffer if it is the
903 * first error (overwriting any prior warnings).
905 if (is_error ? (ps->nerrors)++ == 0 :
906 (ps->nwarnings)++ == 0 && ps->nerrors == 0)
907 store_message(ps, pp, ps->error, sizeof ps->error, 0, message);
910 store_verbose(ps, pp, is_error ? "error: " : "warning: ", message);
913 #ifdef PNG_READ_SUPPORTED
914 /* Internal error function, called with a png_store but no libpng stuff. */
916 internal_error(png_store *ps, png_const_charp message)
918 store_log(ps, NULL, message, 1 /* error */);
920 /* And finally throw an exception. */
922 struct exception_context *the_exception_context = &ps->exception_context;
926 #endif /* PNG_READ_SUPPORTED */
928 /* Functions to use as PNG callbacks. */
930 store_error(png_structp ppIn, png_const_charp message) /* PNG_NORETURN */
932 png_const_structp pp = ppIn;
933 png_store *ps = voidcast(png_store*, png_get_error_ptr(pp));
935 if (!ps->expect_error)
936 store_log(ps, pp, message, 1 /* error */);
938 /* And finally throw an exception. */
940 struct exception_context *the_exception_context = &ps->exception_context;
946 store_warning(png_structp ppIn, png_const_charp message)
948 png_const_structp pp = ppIn;
949 png_store *ps = voidcast(png_store*, png_get_error_ptr(pp));
951 if (!ps->expect_warning)
952 store_log(ps, pp, message, 0 /* warning */);
957 /* These somewhat odd functions are used when reading an image to ensure that
958 * the buffer is big enough, the png_structp is for errors.
960 /* Return a single row from the correct image. */
962 store_image_row(PNG_CONST png_store* ps, png_const_structp pp, int nImage,
965 png_size_t coffset = (nImage * ps->image_h + y) * (ps->cb_row + 5) + 2;
967 if (ps->image == NULL)
968 png_error(pp, "no allocated image");
970 if (coffset + ps->cb_row + 3 > ps->cb_image)
971 png_error(pp, "image too small");
973 return ps->image + coffset;
977 store_image_free(png_store *ps, png_const_structp pp)
979 if (ps->image != NULL)
981 png_bytep image = ps->image;
983 if (image[-1] != 0xed || image[ps->cb_image] != 0xfe)
986 png_error(pp, "png_store image overwrite (1)");
988 store_log(ps, NULL, "png_store image overwrite (2)", 1);
999 store_ensure_image(png_store *ps, png_const_structp pp, int nImages,
1000 png_size_t cbRow, png_uint_32 cRows)
1002 png_size_t cb = nImages * cRows * (cbRow + 5);
1004 if (ps->cb_image < cb)
1008 store_image_free(ps, pp);
1010 /* The buffer is deliberately mis-aligned. */
1011 image = voidcast(png_bytep, malloc(cb+2));
1014 /* Called from the startup - ignore the error for the moment. */
1018 png_error(pp, "OOM allocating image buffer");
1021 /* These magic tags are used to detect overwrites above. */
1030 /* We have an adequate sized image; lay out the rows. There are 2 bytes at
1031 * the start and three at the end of each (this ensures that the row
1032 * alignment starts out odd - 2+1 and changes for larger images on each row.)
1035 ps->image_h = cRows;
1037 /* For error checking, the whole buffer is set to 10110010 (0xb2 - 178).
1038 * This deliberately doesn't match the bits in the size test image which are
1039 * outside the image; these are set to 0xff (all 1). To make the row
1040 * comparison work in the 'size' test case the size rows are pre-initialized
1041 * to the same value prior to calling 'standard_row'.
1043 memset(ps->image, 178, cb);
1045 /* Then put in the marks. */
1046 while (--nImages >= 0)
1050 for (y=0; y<cRows; ++y)
1052 png_bytep row = store_image_row(ps, pp, nImages, y);
1064 #ifdef PNG_READ_SUPPORTED
1066 store_image_check(PNG_CONST png_store* ps, png_const_structp pp, int iImage)
1068 png_const_bytep image = ps->image;
1070 if (image[-1] != 0xed || image[ps->cb_image] != 0xfe)
1071 png_error(pp, "image overwrite");
1074 png_size_t cbRow = ps->cb_row;
1075 png_uint_32 rows = ps->image_h;
1077 image += iImage * (cbRow+5) * ps->image_h;
1079 image += 2; /* skip image first row markers */
1083 if (image[-2] != 190 || image[-1] != 239)
1084 png_error(pp, "row start overwritten");
1086 if (image[cbRow] != 222 || image[cbRow+1] != 173 ||
1087 image[cbRow+2] != 17)
1088 png_error(pp, "row end overwritten");
1094 #endif /* PNG_READ_SUPPORTED */
1096 static void PNGCBAPI
1097 store_write(png_structp ppIn, png_bytep pb, png_size_t st)
1099 png_const_structp pp = ppIn;
1100 png_store *ps = voidcast(png_store*, png_get_io_ptr(pp));
1102 if (ps->pwrite != pp)
1103 png_error(pp, "store state damaged");
1109 if (ps->writepos >= STORE_BUFFER_SIZE)
1114 if (cb > STORE_BUFFER_SIZE - ps->writepos)
1115 cb = STORE_BUFFER_SIZE - ps->writepos;
1117 memcpy(ps->new.buffer + ps->writepos, pb, cb);
1124 static void PNGCBAPI
1125 store_flush(png_structp ppIn)
1127 UNUSED(ppIn) /*DOES NOTHING*/
1130 #ifdef PNG_READ_SUPPORTED
1132 store_read_buffer_size(png_store *ps)
1134 /* Return the bytes available for read in the current buffer. */
1135 if (ps->next != &ps->current->data)
1136 return STORE_BUFFER_SIZE;
1138 return ps->current->datacount;
1141 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1142 /* Return total bytes available for read. */
1144 store_read_buffer_avail(png_store *ps)
1146 if (ps->current != NULL && ps->next != NULL)
1148 png_store_buffer *next = &ps->current->data;
1149 size_t cbAvail = ps->current->datacount;
1151 while (next != ps->next && next != NULL)
1154 cbAvail += STORE_BUFFER_SIZE;
1157 if (next != ps->next)
1158 png_error(ps->pread, "buffer read error");
1160 if (cbAvail > ps->readpos)
1161 return cbAvail - ps->readpos;
1169 store_read_buffer_next(png_store *ps)
1171 png_store_buffer *pbOld = ps->next;
1172 png_store_buffer *pbNew = &ps->current->data;
1175 while (pbNew != NULL && pbNew->prev != pbOld)
1176 pbNew = pbNew->prev;
1185 png_error(ps->pread, "buffer lost");
1188 return 0; /* EOF or error */
1191 /* Need separate implementation and callback to allow use of the same code
1192 * during progressive read, where the io_ptr is set internally by libpng.
1195 store_read_imp(png_store *ps, png_bytep pb, png_size_t st)
1197 if (ps->current == NULL || ps->next == NULL)
1198 png_error(ps->pread, "store state damaged");
1202 size_t cbAvail = store_read_buffer_size(ps) - ps->readpos;
1206 if (cbAvail > st) cbAvail = st;
1207 memcpy(pb, ps->next->buffer + ps->readpos, cbAvail);
1210 ps->readpos += cbAvail;
1213 else if (!store_read_buffer_next(ps))
1214 png_error(ps->pread, "read beyond end of file");
1218 static void PNGCBAPI
1219 store_read(png_structp ppIn, png_bytep pb, png_size_t st)
1221 png_const_structp pp = ppIn;
1222 png_store *ps = voidcast(png_store*, png_get_io_ptr(pp));
1224 if (ps == NULL || ps->pread != pp)
1225 png_error(pp, "bad store read call");
1227 store_read_imp(ps, pb, st);
1231 store_progressive_read(png_store *ps, png_structp pp, png_infop pi)
1233 /* Notice that a call to store_read will cause this function to fail because
1234 * readpos will be set.
1236 if (ps->pread != pp || ps->current == NULL || ps->next == NULL)
1237 png_error(pp, "store state damaged (progressive)");
1241 if (ps->readpos != 0)
1242 png_error(pp, "store_read called during progressive read");
1244 png_process_data(pp, pi, ps->next->buffer, store_read_buffer_size(ps));
1246 while (store_read_buffer_next(ps));
1248 #endif /* PNG_READ_SUPPORTED */
1250 /* The caller must fill this in: */
1251 static store_palette_entry *
1252 store_write_palette(png_store *ps, int npalette)
1254 if (ps->pwrite == NULL)
1255 store_log(ps, NULL, "attempt to write palette without write stream", 1);
1257 if (ps->palette != NULL)
1258 png_error(ps->pwrite, "multiple store_write_palette calls");
1260 /* This function can only return NULL if called with '0'! */
1263 ps->palette = voidcast(store_palette_entry*, malloc(npalette *
1264 sizeof *ps->palette));
1266 if (ps->palette == NULL)
1267 png_error(ps->pwrite, "store new palette: OOM");
1269 ps->npalette = npalette;
1275 #ifdef PNG_READ_SUPPORTED
1276 static store_palette_entry *
1277 store_current_palette(png_store *ps, int *npalette)
1279 /* This is an internal error (the call has been made outside a read
1282 if (ps->current == NULL)
1283 store_log(ps, ps->pread, "no current stream for palette", 1);
1285 /* The result may be null if there is no palette. */
1286 *npalette = ps->current->npalette;
1287 return ps->current->palette;
1289 #endif /* PNG_READ_SUPPORTED */
1291 /***************************** MEMORY MANAGEMENT*** ***************************/
1292 #ifdef PNG_USER_MEM_SUPPORTED
1293 /* A store_memory is simply the header for an allocated block of memory. The
1294 * pointer returned to libpng is just after the end of the header block, the
1295 * allocated memory is followed by a second copy of the 'mark'.
1297 typedef struct store_memory
1299 store_pool *pool; /* Originating pool */
1300 struct store_memory *next; /* Singly linked list */
1301 png_alloc_size_t size; /* Size of memory allocated */
1302 png_byte mark[4]; /* ID marker */
1305 /* Handle a fatal error in memory allocation. This calls png_error if the
1306 * libpng struct is non-NULL, else it outputs a message and returns. This means
1307 * that a memory problem while libpng is running will abort (png_error) the
1308 * handling of particular file while one in cleanup (after the destroy of the
1309 * struct has returned) will simply keep going and free (or attempt to free)
1313 store_pool_error(png_store *ps, png_const_structp pp, PNG_CONST char *msg)
1318 /* Else we have to do it ourselves. png_error eventually calls store_log,
1319 * above. store_log accepts a NULL png_structp - it just changes what gets
1320 * output by store_message.
1322 store_log(ps, pp, msg, 1 /* error */);
1326 store_memory_free(png_const_structp pp, store_pool *pool, store_memory *memory)
1328 /* Note that pp may be NULL (see store_pool_delete below), the caller has
1329 * found 'memory' in pool->list *and* unlinked this entry, so this is a valid
1330 * pointer (for sure), but the contents may have been trashed.
1332 if (memory->pool != pool)
1333 store_pool_error(pool->store, pp, "memory corrupted (pool)");
1335 else if (memcmp(memory->mark, pool->mark, sizeof memory->mark) != 0)
1336 store_pool_error(pool->store, pp, "memory corrupted (start)");
1338 /* It should be safe to read the size field now. */
1341 png_alloc_size_t cb = memory->size;
1344 store_pool_error(pool->store, pp, "memory corrupted (size)");
1346 else if (memcmp((png_bytep)(memory+1)+cb, pool->mark, sizeof pool->mark)
1348 store_pool_error(pool->store, pp, "memory corrupted (end)");
1350 /* Finally give the library a chance to find problems too: */
1353 pool->current -= cb;
1360 store_pool_delete(png_store *ps, store_pool *pool)
1362 if (pool->list != NULL)
1364 fprintf(stderr, "%s: %s %s: memory lost (list follows):\n", ps->test,
1365 pool == &ps->read_memory_pool ? "read" : "write",
1366 pool == &ps->read_memory_pool ? (ps->current != NULL ?
1367 ps->current->name : "unknown file") : ps->wname);
1372 store_memory *next = pool->list;
1373 pool->list = next->next;
1376 fprintf(stderr, "\t%lu bytes @ %p\n",
1377 (unsigned long)next->size, (PNG_CONST void*)(next+1));
1378 /* The NULL means this will always return, even if the memory is
1381 store_memory_free(NULL, pool, next);
1383 while (pool->list != NULL);
1386 /* And reset the other fields too for the next time. */
1387 if (pool->max > pool->max_max) pool->max_max = pool->max;
1389 if (pool->current != 0) /* unexpected internal error */
1390 fprintf(stderr, "%s: %s %s: memory counter mismatch (internal error)\n",
1391 ps->test, pool == &ps->read_memory_pool ? "read" : "write",
1392 pool == &ps->read_memory_pool ? (ps->current != NULL ?
1393 ps->current->name : "unknown file") : ps->wname);
1396 if (pool->limit > pool->max_limit)
1397 pool->max_limit = pool->limit;
1401 if (pool->total > pool->max_total)
1402 pool->max_total = pool->total;
1406 /* Get a new mark too. */
1407 store_pool_mark(pool->mark);
1410 /* The memory callbacks: */
1411 static png_voidp PNGCBAPI
1412 store_malloc(png_structp ppIn, png_alloc_size_t cb)
1414 png_const_structp pp = ppIn;
1415 store_pool *pool = voidcast(store_pool*, png_get_mem_ptr(pp));
1416 store_memory *new = voidcast(store_memory*, malloc(cb + (sizeof *new) +
1417 (sizeof pool->mark)));
1424 pool->current += cb;
1426 if (pool->current > pool->limit)
1427 pool->limit = pool->current;
1432 memcpy(new->mark, pool->mark, sizeof new->mark);
1433 memcpy((png_byte*)(new+1) + cb, pool->mark, sizeof pool->mark);
1435 new->next = pool->list;
1442 /* NOTE: the PNG user malloc function cannot use the png_ptr it is passed
1443 * other than to retrieve the allocation pointer! libpng calls the
1444 * store_malloc callback in two basic cases:
1446 * 1) From png_malloc; png_malloc will do a png_error itself if NULL is
1448 * 2) From png_struct or png_info structure creation; png_malloc is
1449 * to return so cleanup can be performed.
1451 * To handle this store_malloc can log a message, but can't do anything
1454 store_log(pool->store, pp, "out of memory", 1 /* is_error */);
1460 static void PNGCBAPI
1461 store_free(png_structp ppIn, png_voidp memory)
1463 png_const_structp pp = ppIn;
1464 store_pool *pool = voidcast(store_pool*, png_get_mem_ptr(pp));
1465 store_memory *this = voidcast(store_memory*, memory), **test;
1467 /* Because libpng calls store_free with a dummy png_struct when deleting
1468 * png_struct or png_info via png_destroy_struct_2 it is necessary to check
1469 * the passed in png_structp to ensure it is valid, and not pass it to
1470 * png_error if it is not.
1472 if (pp != pool->store->pread && pp != pool->store->pwrite)
1475 /* First check that this 'memory' really is valid memory - it must be in the
1476 * pool list. If it is, use the shared memory_free function to free it.
1479 for (test = &pool->list; *test != this; test = &(*test)->next)
1483 store_pool_error(pool->store, pp, "bad pointer to free");
1488 /* Unlink this entry, *test == this. */
1491 store_memory_free(pp, pool, this);
1493 #endif /* PNG_USER_MEM_SUPPORTED */
1495 /* Setup functions. */
1496 /* Cleanup when aborting a write or after storing the new file. */
1498 store_write_reset(png_store *ps)
1500 if (ps->pwrite != NULL)
1505 png_destroy_write_struct(&ps->pwrite, &ps->piwrite);
1509 /* memory corruption: continue. */
1516 /* And make sure that all the memory has been freed - this will output
1517 * spurious errors in the case of memory corruption above, but this is safe.
1519 # ifdef PNG_USER_MEM_SUPPORTED
1520 store_pool_delete(ps, &ps->write_memory_pool);
1526 /* The following is the main write function, it returns a png_struct and,
1527 * optionally, a png_info suitable for writiing a new PNG file. Use
1528 * store_storefile above to record this file after it has been written. The
1529 * returned libpng structures as destroyed by store_write_reset above.
1532 set_store_for_write(png_store *ps, png_infopp ppi,
1533 PNG_CONST char * volatile name)
1539 if (ps->pwrite != NULL)
1540 png_error(ps->pwrite, "write store already in use");
1542 store_write_reset(ps);
1543 safecat(ps->wname, sizeof ps->wname, 0, name);
1545 /* Don't do the slow memory checks if doing a speed test, also if user
1546 * memory is not supported we can't do it anyway.
1548 # ifdef PNG_USER_MEM_SUPPORTED
1550 ps->pwrite = png_create_write_struct_2(PNG_LIBPNG_VER_STRING,
1551 ps, store_error, store_warning, &ps->write_memory_pool,
1552 store_malloc, store_free);
1556 ps->pwrite = png_create_write_struct(PNG_LIBPNG_VER_STRING,
1557 ps, store_error, store_warning);
1559 png_set_write_fn(ps->pwrite, ps, store_write, store_flush);
1561 # ifdef PNG_SET_OPTION_SUPPORTED
1564 for (opt=0; opt<ps->noptions; ++opt)
1565 if (png_set_option(ps->pwrite, ps->options[opt].option,
1566 ps->options[opt].setting) == PNG_OPTION_INVALID)
1567 png_error(ps->pwrite, "png option invalid");
1572 *ppi = ps->piwrite = png_create_info_struct(ps->pwrite);
1581 /* Cleanup when finished reading (either due to error or in the success case).
1582 * This routine exists even when there is no read support to make the code
1583 * tidier (avoid a mass of ifdefs) and so easier to maintain.
1586 store_read_reset(png_store *ps)
1588 # ifdef PNG_READ_SUPPORTED
1589 if (ps->pread != NULL)
1594 png_destroy_read_struct(&ps->pread, &ps->piread, NULL);
1598 /* error already output: continue */
1606 # ifdef PNG_USER_MEM_SUPPORTED
1607 /* Always do this to be safe. */
1608 store_pool_delete(ps, &ps->read_memory_pool);
1617 #ifdef PNG_READ_SUPPORTED
1619 store_read_set(png_store *ps, png_uint_32 id)
1621 png_store_file *pf = ps->saved;
1629 store_read_buffer_next(ps);
1638 char msg[FILE_NAME_SIZE+64];
1640 pos = standard_name_from_id(msg, sizeof msg, 0, id);
1641 pos = safecat(msg, sizeof msg, pos, ": file not found");
1642 png_error(ps->pread, msg);
1646 /* The main interface for reading a saved file - pass the id number of the file
1647 * to retrieve. Ids must be unique or the earlier file will be hidden. The API
1648 * returns a png_struct and, optionally, a png_info. Both of these will be
1649 * destroyed by store_read_reset above.
1652 set_store_for_read(png_store *ps, png_infopp ppi, png_uint_32 id,
1653 PNG_CONST char *name)
1655 /* Set the name for png_error */
1656 safecat(ps->test, sizeof ps->test, 0, name);
1658 if (ps->pread != NULL)
1659 png_error(ps->pread, "read store already in use");
1661 store_read_reset(ps);
1663 /* Both the create APIs can return NULL if used in their default mode
1664 * (because there is no other way of handling an error because the jmp_buf
1665 * by default is stored in png_struct and that has not been allocated!)
1666 * However, given that store_error works correctly in these circumstances
1667 * we don't ever expect NULL in this program.
1669 # ifdef PNG_USER_MEM_SUPPORTED
1671 ps->pread = png_create_read_struct_2(PNG_LIBPNG_VER_STRING, ps,
1672 store_error, store_warning, &ps->read_memory_pool, store_malloc,
1677 ps->pread = png_create_read_struct(PNG_LIBPNG_VER_STRING, ps, store_error,
1680 if (ps->pread == NULL)
1682 struct exception_context *the_exception_context = &ps->exception_context;
1684 store_log(ps, NULL, "png_create_read_struct returned NULL (unexpected)",
1690 # ifdef PNG_SET_OPTION_SUPPORTED
1693 for (opt=0; opt<ps->noptions; ++opt)
1694 if (png_set_option(ps->pread, ps->options[opt].option,
1695 ps->options[opt].setting) == PNG_OPTION_INVALID)
1696 png_error(ps->pread, "png option invalid");
1700 store_read_set(ps, id);
1703 *ppi = ps->piread = png_create_info_struct(ps->pread);
1707 #endif /* PNG_READ_SUPPORTED */
1709 /* The overall cleanup of a store simply calls the above then removes all the
1710 * saved files. This does not delete the store itself.
1713 store_delete(png_store *ps)
1715 store_write_reset(ps);
1716 store_read_reset(ps);
1717 store_freefile(&ps->saved);
1718 store_image_free(ps, NULL);
1721 /*********************** PNG FILE MODIFICATION ON READ ************************/
1722 /* Files may be modified on read. The following structure contains a complete
1723 * png_store together with extra members to handle modification and a special
1724 * read callback for libpng. To use this the 'modifications' field must be set
1725 * to a list of png_modification structures that actually perform the
1726 * modification, otherwise a png_modifier is functionally equivalent to a
1727 * png_store. There is a special read function, set_modifier_for_read, which
1728 * replaces set_store_for_read.
1730 typedef enum modifier_state
1732 modifier_start, /* Initial value */
1733 modifier_signature, /* Have a signature */
1734 modifier_IHDR /* Have an IHDR */
1737 typedef struct CIE_color
1739 /* A single CIE tristimulus value, representing the unique response of a
1740 * standard observer to a variety of light spectra. The observer recognizes
1741 * all spectra that produce this response as the same color, therefore this
1742 * is effectively a description of a color.
1747 typedef struct color_encoding
1749 /* A description of an (R,G,B) encoding of color (as defined above); this
1750 * includes the actual colors of the (R,G,B) triples (1,0,0), (0,1,0) and
1751 * (0,0,1) plus an encoding value that is used to encode the linear
1752 * components R, G and B to give the actual values R^gamma, G^gamma and
1753 * B^gamma that are stored.
1755 double gamma; /* Encoding (file) gamma of space */
1756 CIE_color red, green, blue; /* End points */
1759 #ifdef PNG_READ_SUPPORTED
1761 chromaticity_x(CIE_color c)
1763 return c.X / (c.X + c.Y + c.Z);
1767 chromaticity_y(CIE_color c)
1769 return c.Y / (c.X + c.Y + c.Z);
1773 white_point(PNG_CONST color_encoding *encoding)
1777 white.X = encoding->red.X + encoding->green.X + encoding->blue.X;
1778 white.Y = encoding->red.Y + encoding->green.Y + encoding->blue.Y;
1779 white.Z = encoding->red.Z + encoding->green.Z + encoding->blue.Z;
1784 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1786 normalize_color_encoding(color_encoding *encoding)
1788 PNG_CONST double whiteY = encoding->red.Y + encoding->green.Y +
1793 encoding->red.X /= whiteY;
1794 encoding->red.Y /= whiteY;
1795 encoding->red.Z /= whiteY;
1796 encoding->green.X /= whiteY;
1797 encoding->green.Y /= whiteY;
1798 encoding->green.Z /= whiteY;
1799 encoding->blue.X /= whiteY;
1800 encoding->blue.Y /= whiteY;
1801 encoding->blue.Z /= whiteY;
1807 safecat_color_encoding(char *buffer, size_t bufsize, size_t pos,
1808 PNG_CONST color_encoding *e, double encoding_gamma)
1812 if (encoding_gamma != 0)
1813 pos = safecat(buffer, bufsize, pos, "(");
1814 pos = safecat(buffer, bufsize, pos, "R(");
1815 pos = safecatd(buffer, bufsize, pos, e->red.X, 4);
1816 pos = safecat(buffer, bufsize, pos, ",");
1817 pos = safecatd(buffer, bufsize, pos, e->red.Y, 4);
1818 pos = safecat(buffer, bufsize, pos, ",");
1819 pos = safecatd(buffer, bufsize, pos, e->red.Z, 4);
1820 pos = safecat(buffer, bufsize, pos, "),G(");
1821 pos = safecatd(buffer, bufsize, pos, e->green.X, 4);
1822 pos = safecat(buffer, bufsize, pos, ",");
1823 pos = safecatd(buffer, bufsize, pos, e->green.Y, 4);
1824 pos = safecat(buffer, bufsize, pos, ",");
1825 pos = safecatd(buffer, bufsize, pos, e->green.Z, 4);
1826 pos = safecat(buffer, bufsize, pos, "),B(");
1827 pos = safecatd(buffer, bufsize, pos, e->blue.X, 4);
1828 pos = safecat(buffer, bufsize, pos, ",");
1829 pos = safecatd(buffer, bufsize, pos, e->blue.Y, 4);
1830 pos = safecat(buffer, bufsize, pos, ",");
1831 pos = safecatd(buffer, bufsize, pos, e->blue.Z, 4);
1832 pos = safecat(buffer, bufsize, pos, ")");
1833 if (encoding_gamma != 0)
1834 pos = safecat(buffer, bufsize, pos, ")");
1837 if (encoding_gamma != 0)
1839 pos = safecat(buffer, bufsize, pos, "^");
1840 pos = safecatd(buffer, bufsize, pos, encoding_gamma, 5);
1845 #endif /* PNG_READ_SUPPORTED */
1847 typedef struct png_modifier
1849 png_store this; /* I am a png_store */
1850 struct png_modification *modifications; /* Changes to make */
1852 modifier_state state; /* My state */
1854 /* Information from IHDR: */
1855 png_byte bit_depth; /* From IHDR */
1856 png_byte colour_type; /* From IHDR */
1858 /* While handling PLTE, IDAT and IEND these chunks may be pended to allow
1859 * other chunks to be inserted.
1861 png_uint_32 pending_len;
1862 png_uint_32 pending_chunk;
1866 unsigned int ngammas;
1867 unsigned int ngamma_tests; /* Number of gamma tests to run*/
1868 double current_gamma; /* 0 if not set */
1869 PNG_CONST color_encoding *encodings;
1870 unsigned int nencodings;
1871 PNG_CONST color_encoding *current_encoding; /* If an encoding has been set */
1872 unsigned int encoding_counter; /* For iteration */
1873 int encoding_ignored; /* Something overwrote it */
1875 /* Control variables used to iterate through possible encodings, the
1876 * following must be set to 0 and tested by the function that uses the
1877 * png_modifier because the modifier only sets it to 1 (true.)
1879 unsigned int repeat :1; /* Repeat this transform test. */
1880 unsigned int test_uses_encoding :1;
1882 /* Lowest sbit to test (libpng fails for sbit < 8) */
1885 /* Error control - these are the limits on errors accepted by the gamma tests
1888 double maxout8; /* Maximum output value error */
1889 double maxabs8; /* Absolute sample error 0..1 */
1890 double maxcalc8; /* Absolute sample error 0..1 */
1891 double maxpc8; /* Percentage sample error 0..100% */
1892 double maxout16; /* Maximum output value error */
1893 double maxabs16; /* Absolute sample error 0..1 */
1894 double maxcalc16;/* Absolute sample error 0..1 */
1895 double maxcalcG; /* Absolute sample error 0..1 */
1896 double maxpc16; /* Percentage sample error 0..100% */
1898 /* This is set by transforms that need to allow a higher limit, it is an
1899 * internal check on pngvalid to ensure that the calculated error limits are
1900 * not ridiculous; without this it is too easy to make a mistake in pngvalid
1901 * that allows any value through.
1903 double limit; /* limit on error values, normally 4E-3 */
1905 /* Log limits - values above this are logged, but not necessarily
1908 double log8; /* Absolute error in 8 bits to log */
1909 double log16; /* Absolute error in 16 bits to log */
1911 /* Logged 8 and 16 bit errors ('output' values): */
1912 double error_gray_2;
1913 double error_gray_4;
1914 double error_gray_8;
1915 double error_gray_16;
1916 double error_color_8;
1917 double error_color_16;
1918 double error_indexed;
1921 /* Whether to call png_read_update_info, not png_read_start_image, and how
1922 * many times to call it.
1924 int use_update_info;
1926 /* Whether or not to interlace. */
1927 int interlace_type :9; /* int, but must store '1' */
1929 /* Run the standard tests? */
1930 unsigned int test_standard :1;
1932 /* Run the odd-sized image and interlace read/write tests? */
1933 unsigned int test_size :1;
1935 /* Run tests on reading with a combination of transforms, */
1936 unsigned int test_transform :1;
1938 /* When to use the use_input_precision option, this controls the gamma
1939 * validation code checks. If set any value that is within the transformed
1940 * range input-.5 to input+.5 will be accepted, otherwise the value must be
1941 * within the normal limits. It should not be necessary to set this; the
1942 * result should always be exact within the permitted error limits.
1944 unsigned int use_input_precision :1;
1945 unsigned int use_input_precision_sbit :1;
1946 unsigned int use_input_precision_16to8 :1;
1948 /* If set assume that the calculation bit depth is set by the input
1949 * precision, not the output precision.
1951 unsigned int calculations_use_input_precision :1;
1953 /* If set assume that the calculations are done in 16 bits even if the sample
1956 unsigned int assume_16_bit_calculations :1;
1958 /* Which gamma tests to run: */
1959 unsigned int test_gamma_threshold :1;
1960 unsigned int test_gamma_transform :1; /* main tests */
1961 unsigned int test_gamma_sbit :1;
1962 unsigned int test_gamma_scale16 :1;
1963 unsigned int test_gamma_background :1;
1964 unsigned int test_gamma_alpha_mode :1;
1965 unsigned int test_gamma_expand16 :1;
1966 unsigned int test_exhaustive :1;
1968 unsigned int log :1; /* Log max error */
1970 /* Buffer information, the buffer size limits the size of the chunks that can
1971 * be modified - they must fit (including header and CRC) into the buffer!
1973 size_t flush; /* Count of bytes to flush */
1974 size_t buffer_count; /* Bytes in buffer */
1975 size_t buffer_position; /* Position in buffer */
1976 png_byte buffer[1024];
1979 /* This returns true if the test should be stopped now because it has already
1980 * failed and it is running silently.
1982 static int fail(png_modifier *pm)
1984 return !pm->log && !pm->this.verbose && (pm->this.nerrors > 0 ||
1985 (pm->this.treat_warnings_as_errors && pm->this.nwarnings > 0));
1989 modifier_init(png_modifier *pm)
1991 memset(pm, 0, sizeof *pm);
1992 store_init(&pm->this);
1993 pm->modifications = NULL;
1994 pm->state = modifier_start;
1997 pm->ngamma_tests = 0;
1999 pm->current_gamma = 0;
2002 pm->current_encoding = 0;
2003 pm->encoding_counter = 0;
2004 pm->encoding_ignored = 0;
2006 pm->test_uses_encoding = 0;
2007 pm->maxout8 = pm->maxpc8 = pm->maxabs8 = pm->maxcalc8 = 0;
2008 pm->maxout16 = pm->maxpc16 = pm->maxabs16 = pm->maxcalc16 = 0;
2011 pm->log8 = pm->log16 = 0; /* Means 'off' */
2012 pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = 0;
2013 pm->error_gray_16 = pm->error_color_8 = pm->error_color_16 = 0;
2014 pm->error_indexed = 0;
2015 pm->use_update_info = 0;
2016 pm->interlace_type = PNG_INTERLACE_NONE;
2017 pm->test_standard = 0;
2019 pm->test_transform = 0;
2020 pm->use_input_precision = 0;
2021 pm->use_input_precision_sbit = 0;
2022 pm->use_input_precision_16to8 = 0;
2023 pm->calculations_use_input_precision = 0;
2024 pm->assume_16_bit_calculations = 0;
2025 pm->test_gamma_threshold = 0;
2026 pm->test_gamma_transform = 0;
2027 pm->test_gamma_sbit = 0;
2028 pm->test_gamma_scale16 = 0;
2029 pm->test_gamma_background = 0;
2030 pm->test_gamma_alpha_mode = 0;
2031 pm->test_gamma_expand16 = 0;
2032 pm->test_exhaustive = 0;
2035 /* Rely on the memset for all the other fields - there are no pointers */
2038 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
2040 /* This controls use of checks that explicitly know how libpng digitizes the
2041 * samples in calculations; setting this circumvents simple error limit checking
2042 * in the rgb_to_gray check, replacing it with an exact copy of the libpng 1.5
2045 #define DIGITIZE PNG_LIBPNG_VER < 10700
2047 /* If pm->calculations_use_input_precision is set then operations will happen
2048 * with the precision of the input, not the precision of the output depth.
2050 * If pm->assume_16_bit_calculations is set then even 8 bit calculations use 16
2051 * bit precision. This only affects those of the following limits that pertain
2052 * to a calculation - not a digitization operation - unless the following API is
2055 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2057 static double digitize(double value, int depth, int do_round)
2059 /* 'value' is in the range 0 to 1, the result is the same value rounded to a
2060 * multiple of the digitization factor - 8 or 16 bits depending on both the
2061 * sample depth and the 'assume' setting. Digitization is normally by
2062 * rounding and 'do_round' should be 1, if it is 0 the digitized value will
2065 PNG_CONST unsigned int digitization_factor = (1U << depth) -1;
2067 /* Limiting the range is done as a convenience to the caller - it's easier to
2068 * do it once here than every time at the call site.
2073 else if (value >= 1)
2076 value *= digitization_factor;
2077 if (do_round) value += .5;
2078 return floor(value)/digitization_factor;
2081 #endif /* RGB_TO_GRAY */
2083 #ifdef PNG_READ_GAMMA_SUPPORTED
2084 static double abserr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
2086 /* Absolute error permitted in linear values - affected by the bit depth of
2089 if (pm->assume_16_bit_calculations ||
2090 (pm->calculations_use_input_precision ? in_depth : out_depth) == 16)
2091 return pm->maxabs16;
2096 static double calcerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
2098 /* Error in the linear composition arithmetic - only relevant when
2099 * composition actually happens (0 < alpha < 1).
2101 if ((pm->calculations_use_input_precision ? in_depth : out_depth) == 16)
2102 return pm->maxcalc16;
2103 else if (pm->assume_16_bit_calculations)
2104 return pm->maxcalcG;
2106 return pm->maxcalc8;
2109 static double pcerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
2111 /* Percentage error permitted in the linear values. Note that the specified
2112 * value is a percentage but this routine returns a simple number.
2114 if (pm->assume_16_bit_calculations ||
2115 (pm->calculations_use_input_precision ? in_depth : out_depth) == 16)
2116 return pm->maxpc16 * .01;
2118 return pm->maxpc8 * .01;
2121 /* Output error - the error in the encoded value. This is determined by the
2122 * digitization of the output so can be +/-0.5 in the actual output value. In
2123 * the expand_16 case with the current code in libpng the expand happens after
2124 * all the calculations are done in 8 bit arithmetic, so even though the output
2125 * depth is 16 the output error is determined by the 8 bit calculation.
2127 * This limit is not determined by the bit depth of internal calculations.
2129 * The specified parameter does *not* include the base .5 digitization error but
2132 static double outerr(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
2134 /* There is a serious error in the 2 and 4 bit grayscale transform because
2135 * the gamma table value (8 bits) is simply shifted, not rounded, so the
2136 * error in 4 bit grayscale gamma is up to the value below. This is a hack
2137 * to allow pngvalid to succeed:
2139 * TODO: fix this in libpng
2147 if ((pm->calculations_use_input_precision ? in_depth : out_depth) == 16)
2148 return pm->maxout16;
2150 /* This is the case where the value was calculated at 8-bit precision then
2151 * scaled to 16 bits.
2153 else if (out_depth == 16)
2154 return pm->maxout8 * 257;
2160 /* This does the same thing as the above however it returns the value to log,
2161 * rather than raising a warning. This is useful for debugging to track down
2162 * exactly what set of parameters cause high error values.
2164 static double outlog(PNG_CONST png_modifier *pm, int in_depth, int out_depth)
2166 /* The command line parameters are either 8 bit (0..255) or 16 bit (0..65535)
2167 * and so must be adjusted for low bit depth grayscale:
2171 if (pm->log8 == 0) /* switched off */
2175 return pm->log8 / 255 * ((1<<out_depth)-1);
2180 if ((pm->calculations_use_input_precision ? in_depth : out_depth) == 16)
2188 /* This is the case where the value was calculated at 8-bit precision then
2189 * scaled to 16 bits.
2194 return pm->log8 * 257;
2197 /* This complements the above by providing the appropriate quantization for the
2198 * final value. Normally this would just be quantization to an integral value,
2199 * but in the 8 bit calculation case it's actually quantization to a multiple of
2202 static int output_quantization_factor(PNG_CONST png_modifier *pm, int in_depth,
2205 if (out_depth == 16 && in_depth != 16 &&
2206 pm->calculations_use_input_precision)
2211 #endif /* PNG_READ_GAMMA_SUPPORTED */
2213 /* One modification structure must be provided for each chunk to be modified (in
2214 * fact more than one can be provided if multiple separate changes are desired
2215 * for a single chunk.) Modifications include adding a new chunk when a
2216 * suitable chunk does not exist.
2218 * The caller of modify_fn will reset the CRC of the chunk and record 'modified'
2219 * or 'added' as appropriate if the modify_fn returns 1 (true). If the
2220 * modify_fn is NULL the chunk is simply removed.
2222 typedef struct png_modification
2224 struct png_modification *next;
2227 /* If the following is NULL all matching chunks will be removed: */
2228 int (*modify_fn)(struct png_modifier *pm,
2229 struct png_modification *me, int add);
2231 /* If the following is set to PLTE, IDAT or IEND and the chunk has not been
2232 * found and modified (and there is a modify_fn) the modify_fn will be called
2233 * to add the chunk before the relevant chunk.
2236 unsigned int modified :1; /* Chunk was modified */
2237 unsigned int added :1; /* Chunk was added */
2238 unsigned int removed :1; /* Chunk was removed */
2242 modification_reset(png_modification *pmm)
2249 modification_reset(pmm->next);
2254 modification_init(png_modification *pmm)
2256 memset(pmm, 0, sizeof *pmm);
2259 pmm->modify_fn = NULL;
2261 modification_reset(pmm);
2264 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
2266 modifier_current_encoding(PNG_CONST png_modifier *pm, color_encoding *ce)
2268 if (pm->current_encoding != 0)
2269 *ce = *pm->current_encoding;
2272 memset(ce, 0, sizeof *ce);
2274 ce->gamma = pm->current_gamma;
2279 safecat_current_encoding(char *buffer, size_t bufsize, size_t pos,
2280 PNG_CONST png_modifier *pm)
2282 pos = safecat_color_encoding(buffer, bufsize, pos, pm->current_encoding,
2285 if (pm->encoding_ignored)
2286 pos = safecat(buffer, bufsize, pos, "[overridden]");
2291 /* Iterate through the usefully testable color encodings. An encoding is one
2294 * 1) Nothing (no color space, no gamma).
2295 * 2) Just a gamma value from the gamma array (including 1.0)
2296 * 3) A color space from the encodings array with the corresponding gamma.
2297 * 4) The same, but with gamma 1.0 (only really useful with 16 bit calculations)
2299 * The iterator selects these in turn, the randomizer selects one at random,
2300 * which is used depends on the setting of the 'test_exhaustive' flag. Notice
2301 * that this function changes the colour space encoding so it must only be
2302 * called on completion of the previous test. This is what 'modifier_reset'
2305 * After the function has been called the 'repeat' flag will still be set; the
2306 * caller of modifier_reset must reset it at the start of each run of the test!
2309 modifier_total_encodings(PNG_CONST png_modifier *pm)
2311 return 1 + /* (1) nothing */
2312 pm->ngammas + /* (2) gamma values to test */
2313 pm->nencodings + /* (3) total number of encodings */
2314 /* The following test only works after the first time through the
2315 * png_modifier code because 'bit_depth' is set when the IHDR is read.
2316 * modifier_reset, below, preserves the setting until after it has called
2317 * the iterate function (also below.)
2319 * For this reason do not rely on this function outside a call to
2322 ((pm->bit_depth == 16 || pm->assume_16_bit_calculations) ?
2323 pm->nencodings : 0); /* (4) encodings with gamma == 1.0 */
2327 modifier_encoding_iterate(png_modifier *pm)
2329 if (!pm->repeat && /* Else something needs the current encoding again. */
2330 pm->test_uses_encoding) /* Some transform is encoding dependent */
2332 if (pm->test_exhaustive)
2334 if (++pm->encoding_counter >= modifier_total_encodings(pm))
2335 pm->encoding_counter = 0; /* This will stop the repeat */
2340 /* Not exhaustive - choose an encoding at random; generate a number in
2341 * the range 1..(max-1), so the result is always non-zero:
2343 if (pm->encoding_counter == 0)
2344 pm->encoding_counter = random_mod(modifier_total_encodings(pm)-1)+1;
2346 pm->encoding_counter = 0;
2349 if (pm->encoding_counter > 0)
2353 else if (!pm->repeat)
2354 pm->encoding_counter = 0;
2358 modifier_reset(png_modifier *pm)
2360 store_read_reset(&pm->this);
2362 pm->pending_len = pm->pending_chunk = 0;
2363 pm->flush = pm->buffer_count = pm->buffer_position = 0;
2364 pm->modifications = NULL;
2365 pm->state = modifier_start;
2366 modifier_encoding_iterate(pm);
2367 /* The following must be set in the next run. In particular
2368 * test_uses_encodings must be set in the _ini function of each transform
2369 * that looks at the encodings. (Not the 'add' function!)
2371 pm->test_uses_encoding = 0;
2372 pm->current_gamma = 0;
2373 pm->current_encoding = 0;
2374 pm->encoding_ignored = 0;
2375 /* These only become value after IHDR is read: */
2376 pm->bit_depth = pm->colour_type = 0;
2379 /* The following must be called before anything else to get the encoding set up
2380 * on the modifier. In particular it must be called before the transform init
2381 * functions are called.
2384 modifier_set_encoding(png_modifier *pm)
2386 /* Set the encoding to the one specified by the current encoding counter,
2387 * first clear out all the settings - this corresponds to an encoding_counter
2390 pm->current_gamma = 0;
2391 pm->current_encoding = 0;
2392 pm->encoding_ignored = 0; /* not ignored yet - happens in _ini functions. */
2394 /* Now, if required, set the gamma and encoding fields. */
2395 if (pm->encoding_counter > 0)
2397 /* The gammas[] array is an array of screen gammas, not encoding gammas,
2398 * so we need the inverse:
2400 if (pm->encoding_counter <= pm->ngammas)
2401 pm->current_gamma = 1/pm->gammas[pm->encoding_counter-1];
2405 unsigned int i = pm->encoding_counter - pm->ngammas;
2407 if (i >= pm->nencodings)
2409 i %= pm->nencodings;
2410 pm->current_gamma = 1; /* Linear, only in the 16 bit case */
2414 pm->current_gamma = pm->encodings[i].gamma;
2416 pm->current_encoding = pm->encodings + i;
2421 /* Enquiry functions to find out what is set. Notice that there is an implicit
2422 * assumption below that the first encoding in the list is the one for sRGB.
2425 modifier_color_encoding_is_sRGB(PNG_CONST png_modifier *pm)
2427 return pm->current_encoding != 0 && pm->current_encoding == pm->encodings &&
2428 pm->current_encoding->gamma == pm->current_gamma;
2432 modifier_color_encoding_is_set(PNG_CONST png_modifier *pm)
2434 return pm->current_gamma != 0;
2437 /* Convenience macros. */
2438 #define CHUNK(a,b,c,d) (((a)<<24)+((b)<<16)+((c)<<8)+(d))
2439 #define CHUNK_IHDR CHUNK(73,72,68,82)
2440 #define CHUNK_PLTE CHUNK(80,76,84,69)
2441 #define CHUNK_IDAT CHUNK(73,68,65,84)
2442 #define CHUNK_IEND CHUNK(73,69,78,68)
2443 #define CHUNK_cHRM CHUNK(99,72,82,77)
2444 #define CHUNK_gAMA CHUNK(103,65,77,65)
2445 #define CHUNK_sBIT CHUNK(115,66,73,84)
2446 #define CHUNK_sRGB CHUNK(115,82,71,66)
2448 /* The guts of modification are performed during a read. */
2450 modifier_crc(png_bytep buffer)
2452 /* Recalculate the chunk CRC - a complete chunk must be in
2453 * the buffer, at the start.
2455 uInt datalen = png_get_uint_32(buffer);
2456 uLong crc = crc32(0, buffer+4, datalen+4);
2457 /* The cast to png_uint_32 is safe because a crc32 is always a 32 bit value.
2459 png_save_uint_32(buffer+datalen+8, (png_uint_32)crc);
2463 modifier_setbuffer(png_modifier *pm)
2465 modifier_crc(pm->buffer);
2466 pm->buffer_count = png_get_uint_32(pm->buffer)+12;
2467 pm->buffer_position = 0;
2470 /* Separate the callback into the actual implementation (which is passed the
2471 * png_modifier explicitly) and the callback, which gets the modifier from the
2475 modifier_read_imp(png_modifier *pm, png_bytep pb, png_size_t st)
2480 png_uint_32 len, chunk;
2481 png_modification *mod;
2483 if (pm->buffer_position >= pm->buffer_count) switch (pm->state)
2485 static png_byte sign[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
2486 case modifier_start:
2487 store_read_imp(&pm->this, pm->buffer, 8); /* size of signature. */
2488 pm->buffer_count = 8;
2489 pm->buffer_position = 0;
2491 if (memcmp(pm->buffer, sign, 8) != 0)
2492 png_error(pm->this.pread, "invalid PNG file signature");
2493 pm->state = modifier_signature;
2496 case modifier_signature:
2497 store_read_imp(&pm->this, pm->buffer, 13+12); /* size of IHDR */
2498 pm->buffer_count = 13+12;
2499 pm->buffer_position = 0;
2501 if (png_get_uint_32(pm->buffer) != 13 ||
2502 png_get_uint_32(pm->buffer+4) != CHUNK_IHDR)
2503 png_error(pm->this.pread, "invalid IHDR");
2505 /* Check the list of modifiers for modifications to the IHDR. */
2506 mod = pm->modifications;
2509 if (mod->chunk == CHUNK_IHDR && mod->modify_fn &&
2510 (*mod->modify_fn)(pm, mod, 0))
2513 modifier_setbuffer(pm);
2516 /* Ignore removal or add if IHDR! */
2520 /* Cache information from the IHDR (the modified one.) */
2521 pm->bit_depth = pm->buffer[8+8];
2522 pm->colour_type = pm->buffer[8+8+1];
2524 pm->state = modifier_IHDR;
2530 /* Read a new chunk and process it until we see PLTE, IDAT or
2531 * IEND. 'flush' indicates that there is still some data to
2532 * output from the preceding chunk.
2534 if ((cb = pm->flush) > 0)
2536 if (cb > st) cb = st;
2538 store_read_imp(&pm->this, pb, cb);
2541 if (st == 0) return;
2544 /* No more bytes to flush, read a header, or handle a pending
2547 if (pm->pending_chunk != 0)
2549 png_save_uint_32(pm->buffer, pm->pending_len);
2550 png_save_uint_32(pm->buffer+4, pm->pending_chunk);
2551 pm->pending_len = 0;
2552 pm->pending_chunk = 0;
2555 store_read_imp(&pm->this, pm->buffer, 8);
2557 pm->buffer_count = 8;
2558 pm->buffer_position = 0;
2560 /* Check for something to modify or a terminator chunk. */
2561 len = png_get_uint_32(pm->buffer);
2562 chunk = png_get_uint_32(pm->buffer+4);
2564 /* Terminators first, they may have to be delayed for added
2567 if (chunk == CHUNK_PLTE || chunk == CHUNK_IDAT ||
2568 chunk == CHUNK_IEND)
2570 mod = pm->modifications;
2574 if ((mod->add == chunk ||
2575 (mod->add == CHUNK_PLTE && chunk == CHUNK_IDAT)) &&
2576 mod->modify_fn != NULL && !mod->modified && !mod->added)
2578 /* Regardless of what the modify function does do not run
2583 if ((*mod->modify_fn)(pm, mod, 1 /*add*/))
2585 /* Reset the CRC on a new chunk */
2586 if (pm->buffer_count > 0)
2587 modifier_setbuffer(pm);
2591 pm->buffer_position = 0;
2595 /* The buffer has been filled with something (we assume)
2596 * so output this. Pend the current chunk.
2598 pm->pending_len = len;
2599 pm->pending_chunk = chunk;
2600 break; /* out of while */
2607 /* Don't do any further processing if the buffer was modified -
2608 * otherwise the code will end up modifying a chunk that was
2612 break; /* out of switch */
2615 /* If we get to here then this chunk may need to be modified. To
2616 * do this it must be less than 1024 bytes in total size, otherwise
2617 * it just gets flushed.
2619 if (len+12 <= sizeof pm->buffer)
2621 store_read_imp(&pm->this, pm->buffer+pm->buffer_count,
2622 len+12-pm->buffer_count);
2623 pm->buffer_count = len+12;
2625 /* Check for a modification, else leave it be. */
2626 mod = pm->modifications;
2629 if (mod->chunk == chunk)
2631 if (mod->modify_fn == NULL)
2633 /* Remove this chunk */
2634 pm->buffer_count = pm->buffer_position = 0;
2636 break; /* Terminate the while loop */
2639 else if ((*mod->modify_fn)(pm, mod, 0))
2642 /* The chunk may have been removed: */
2643 if (pm->buffer_count == 0)
2645 pm->buffer_position = 0;
2648 modifier_setbuffer(pm);
2657 pm->flush = len+12 - pm->buffer_count; /* data + crc */
2659 /* Take the data from the buffer (if there is any). */
2663 /* Here to read from the modifier buffer (not directly from
2664 * the store, as in the flush case above.)
2666 cb = pm->buffer_count - pm->buffer_position;
2671 memcpy(pb, pm->buffer + pm->buffer_position, cb);
2674 pm->buffer_position += cb;
2679 static void PNGCBAPI
2680 modifier_read(png_structp ppIn, png_bytep pb, png_size_t st)
2682 png_const_structp pp = ppIn;
2683 png_modifier *pm = voidcast(png_modifier*, png_get_io_ptr(pp));
2685 if (pm == NULL || pm->this.pread != pp)
2686 png_error(pp, "bad modifier_read call");
2688 modifier_read_imp(pm, pb, st);
2691 /* Like store_progressive_read but the data is getting changed as we go so we
2692 * need a local buffer.
2695 modifier_progressive_read(png_modifier *pm, png_structp pp, png_infop pi)
2697 if (pm->this.pread != pp || pm->this.current == NULL ||
2698 pm->this.next == NULL)
2699 png_error(pp, "store state damaged (progressive)");
2701 /* This is another Horowitz and Hill random noise generator. In this case
2702 * the aim is to stress the progressive reader with truly horrible variable
2703 * buffer sizes in the range 1..500, so a sequence of 9 bit random numbers
2704 * is generated. We could probably just count from 1 to 32767 and get as
2709 static png_uint_32 noise = 1;
2710 png_size_t cb, cbAvail;
2711 png_byte buffer[512];
2713 /* Generate 15 more bits of stuff: */
2714 noise = (noise << 9) | ((noise ^ (noise >> (9-5))) & 0x1ff);
2717 /* Check that this number of bytes are available (in the current buffer.)
2718 * (This doesn't quite work - the modifier might delete a chunk; unlikely
2719 * but possible, it doesn't happen at present because the modifier only
2720 * adds chunks to standard images.)
2722 cbAvail = store_read_buffer_avail(&pm->this);
2723 if (pm->buffer_count > pm->buffer_position)
2724 cbAvail += pm->buffer_count - pm->buffer_position;
2728 /* Check for EOF: */
2735 modifier_read_imp(pm, buffer, cb);
2736 png_process_data(pp, pi, buffer, cb);
2739 /* Check the invariants at the end (if this fails it's a problem in this
2742 if (pm->buffer_count > pm->buffer_position ||
2743 pm->this.next != &pm->this.current->data ||
2744 pm->this.readpos < pm->this.current->datacount)
2745 png_error(pp, "progressive read implementation error");
2748 /* Set up a modifier. */
2750 set_modifier_for_read(png_modifier *pm, png_infopp ppi, png_uint_32 id,
2751 PNG_CONST char *name)
2753 /* Do this first so that the modifier fields are cleared even if an error
2754 * happens allocating the png_struct. No allocation is done here so no
2755 * cleanup is required.
2757 pm->state = modifier_start;
2759 pm->colour_type = 255;
2761 pm->pending_len = 0;
2762 pm->pending_chunk = 0;
2764 pm->buffer_count = 0;
2765 pm->buffer_position = 0;
2767 return set_store_for_read(&pm->this, ppi, id, name);
2771 /******************************** MODIFICATIONS *******************************/
2772 /* Standard modifications to add chunks. These do not require the _SUPPORTED
2773 * macros because the chunks can be there regardless of whether this specific
2774 * libpng supports them.
2776 typedef struct gama_modification
2778 png_modification this;
2779 png_fixed_point gamma;
2780 } gama_modification;
2783 gama_modify(png_modifier *pm, png_modification *me, int add)
2786 /* This simply dumps the given gamma value into the buffer. */
2787 png_save_uint_32(pm->buffer, 4);
2788 png_save_uint_32(pm->buffer+4, CHUNK_gAMA);
2789 png_save_uint_32(pm->buffer+8, ((gama_modification*)me)->gamma);
2794 gama_modification_init(gama_modification *me, png_modifier *pm, double gammad)
2798 modification_init(&me->this);
2799 me->this.chunk = CHUNK_gAMA;
2800 me->this.modify_fn = gama_modify;
2801 me->this.add = CHUNK_PLTE;
2803 me->gamma = (png_fixed_point)g;
2804 me->this.next = pm->modifications;
2805 pm->modifications = &me->this;
2808 typedef struct chrm_modification
2810 png_modification this;
2811 PNG_CONST color_encoding *encoding;
2812 png_fixed_point wx, wy, rx, ry, gx, gy, bx, by;
2813 } chrm_modification;
2816 chrm_modify(png_modifier *pm, png_modification *me, int add)
2819 /* As with gAMA this just adds the required cHRM chunk to the buffer. */
2820 png_save_uint_32(pm->buffer , 32);
2821 png_save_uint_32(pm->buffer+ 4, CHUNK_cHRM);
2822 png_save_uint_32(pm->buffer+ 8, ((chrm_modification*)me)->wx);
2823 png_save_uint_32(pm->buffer+12, ((chrm_modification*)me)->wy);
2824 png_save_uint_32(pm->buffer+16, ((chrm_modification*)me)->rx);
2825 png_save_uint_32(pm->buffer+20, ((chrm_modification*)me)->ry);
2826 png_save_uint_32(pm->buffer+24, ((chrm_modification*)me)->gx);
2827 png_save_uint_32(pm->buffer+28, ((chrm_modification*)me)->gy);
2828 png_save_uint_32(pm->buffer+32, ((chrm_modification*)me)->bx);
2829 png_save_uint_32(pm->buffer+36, ((chrm_modification*)me)->by);
2834 chrm_modification_init(chrm_modification *me, png_modifier *pm,
2835 PNG_CONST color_encoding *encoding)
2837 CIE_color white = white_point(encoding);
2839 /* Original end points: */
2840 me->encoding = encoding;
2842 /* Chromaticities (in fixed point): */
2843 me->wx = fix(chromaticity_x(white));
2844 me->wy = fix(chromaticity_y(white));
2846 me->rx = fix(chromaticity_x(encoding->red));
2847 me->ry = fix(chromaticity_y(encoding->red));
2848 me->gx = fix(chromaticity_x(encoding->green));
2849 me->gy = fix(chromaticity_y(encoding->green));
2850 me->bx = fix(chromaticity_x(encoding->blue));
2851 me->by = fix(chromaticity_y(encoding->blue));
2853 modification_init(&me->this);
2854 me->this.chunk = CHUNK_cHRM;
2855 me->this.modify_fn = chrm_modify;
2856 me->this.add = CHUNK_PLTE;
2857 me->this.next = pm->modifications;
2858 pm->modifications = &me->this;
2861 typedef struct srgb_modification
2863 png_modification this;
2865 } srgb_modification;
2868 srgb_modify(png_modifier *pm, png_modification *me, int add)
2871 /* As above, ignore add and just make a new chunk */
2872 png_save_uint_32(pm->buffer, 1);
2873 png_save_uint_32(pm->buffer+4, CHUNK_sRGB);
2874 pm->buffer[8] = ((srgb_modification*)me)->intent;
2879 srgb_modification_init(srgb_modification *me, png_modifier *pm, png_byte intent)
2881 modification_init(&me->this);
2882 me->this.chunk = CHUNK_sBIT;
2884 if (intent <= 3) /* if valid, else *delete* sRGB chunks */
2886 me->this.modify_fn = srgb_modify;
2887 me->this.add = CHUNK_PLTE;
2888 me->intent = intent;
2893 me->this.modify_fn = 0;
2898 me->this.next = pm->modifications;
2899 pm->modifications = &me->this;
2902 #ifdef PNG_READ_GAMMA_SUPPORTED
2903 typedef struct sbit_modification
2905 png_modification this;
2907 } sbit_modification;
2910 sbit_modify(png_modifier *pm, png_modification *me, int add)
2912 png_byte sbit = ((sbit_modification*)me)->sbit;
2913 if (pm->bit_depth > sbit)
2916 switch (pm->colour_type)
2936 png_error(pm->this.pread,
2937 "unexpected colour type in sBIT modification");
2940 png_save_uint_32(pm->buffer, cb);
2941 png_save_uint_32(pm->buffer+4, CHUNK_sBIT);
2944 (pm->buffer+8)[--cb] = sbit;
2950 /* Remove the sBIT chunk */
2951 pm->buffer_count = pm->buffer_position = 0;
2955 return 0; /* do nothing */
2959 sbit_modification_init(sbit_modification *me, png_modifier *pm, png_byte sbit)
2961 modification_init(&me->this);
2962 me->this.chunk = CHUNK_sBIT;
2963 me->this.modify_fn = sbit_modify;
2964 me->this.add = CHUNK_PLTE;
2966 me->this.next = pm->modifications;
2967 pm->modifications = &me->this;
2969 #endif /* PNG_READ_GAMMA_SUPPORTED */
2970 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
2972 /***************************** STANDARD PNG FILES *****************************/
2973 /* Standard files - write and save standard files. */
2974 /* There are two basic forms of standard images. Those which attempt to have
2975 * all the possible pixel values (not possible for 16bpp images, but a range of
2976 * values are produced) and those which have a range of image sizes. The former
2977 * are used for testing transforms, in particular gamma correction and bit
2978 * reduction and increase. The latter are reserved for testing the behavior of
2979 * libpng with respect to 'odd' image sizes - particularly small images where
2980 * rows become 1 byte and interlace passes disappear.
2982 * The first, most useful, set are the 'transform' images, the second set of
2983 * small images are the 'size' images.
2985 * The transform files are constructed with rows which fit into a 1024 byte row
2986 * buffer. This makes allocation easier below. Further regardless of the file
2987 * format every row has 128 pixels (giving 1024 bytes for 64bpp formats).
2989 * Files are stored with no gAMA or sBIT chunks, with a PLTE only when needed
2990 * and with an ID derived from the colour type, bit depth and interlace type
2991 * as above (FILEID). The width (128) and height (variable) are not stored in
2992 * the FILEID - instead the fields are set to 0, indicating a transform file.
2994 * The size files ar constructed with rows a maximum of 128 bytes wide, allowing
2995 * a maximum width of 16 pixels (for the 64bpp case.) They also have a maximum
2996 * height of 16 rows. The width and height are stored in the FILEID and, being
2997 * non-zero, indicate a size file.
2999 * Because the PNG filter code is typically the largest CPU consumer within
3000 * libpng itself there is a tendency to attempt to optimize it. This results in
3001 * special case code which needs to be validated. To cause this to happen the
3002 * 'size' images are made to use each possible filter, in so far as this is
3003 * possible for smaller images.
3005 * For palette image (colour type 3) multiple transform images are stored with
3006 * the same bit depth to allow testing of more colour combinations -
3007 * particularly important for testing the gamma code because libpng uses a
3008 * different code path for palette images. For size images a single palette is
3012 /* Make a 'standard' palette. Because there are only 256 entries in a palette
3013 * (maximum) this actually makes a random palette in the hope that enough tests
3014 * will catch enough errors. (Note that the same palette isn't produced every
3015 * time for the same test - it depends on what previous tests have been run -
3016 * but a given set of arguments to pngvalid will always produce the same palette
3017 * at the same test! This is why pseudo-random number generators are useful for
3020 * The store must be open for write when this is called, otherwise an internal
3021 * error will occur. This routine contains its own magic number seed, so the
3022 * palettes generated don't change if there are intervening errors (changing the
3023 * calls to the store_mark seed.)
3025 static store_palette_entry *
3026 make_standard_palette(png_store* ps, int npalette, int do_tRNS)
3028 static png_uint_32 palette_seed[2] = { 0x87654321, 9 };
3031 png_byte values[256][4];
3033 /* Always put in black and white plus the six primary and secondary colors.
3037 values[i][1] = (png_byte)((i&1) ? 255U : 0U);
3038 values[i][2] = (png_byte)((i&2) ? 255U : 0U);
3039 values[i][3] = (png_byte)((i&4) ? 255U : 0U);
3042 /* Then add 62 grays (one quarter of the remaining 256 slots). */
3045 png_byte random_bytes[4];
3048 need[0] = 0; /*got black*/
3049 memset(need+1, 1, (sizeof need)-2); /*need these*/
3050 need[255] = 0; /*but not white*/
3058 make_four_random_bytes(palette_seed, random_bytes);
3062 b = random_bytes[--j];
3072 /* Finally add 192 colors at random - don't worry about matches to things we
3073 * already have, chance is less than 1/65536. Don't worry about grays,
3074 * chance is the same, so we get a duplicate or extra gray less than 1 time
3078 make_four_random_bytes(palette_seed, values[i]);
3080 /* Fill in the alpha values in the first byte. Just use all possible values
3081 * (0..255) in an apparently random order:
3084 store_palette_entry *palette;
3085 png_byte selector[4];
3087 make_four_random_bytes(palette_seed, selector);
3090 for (i=0; i<256; ++i)
3091 values[i][0] = (png_byte)(i ^ selector[0]);
3094 for (i=0; i<256; ++i)
3095 values[i][0] = 255; /* no transparency/tRNS chunk */
3097 /* 'values' contains 256 ARGB values, but we only need 'npalette'.
3098 * 'npalette' will always be a power of 2: 2, 4, 16 or 256. In the low
3099 * bit depth cases select colors at random, else it is difficult to have
3100 * a set of low bit depth palette test with any chance of a reasonable
3101 * range of colors. Do this by randomly permuting values into the low
3102 * 'npalette' entries using an XOR mask generated here. This also
3103 * permutes the npalette == 256 case in a potentially useful way (there is
3104 * no relationship between palette index and the color value therein!)
3106 palette = store_write_palette(ps, npalette);
3108 for (i=0; i<npalette; ++i)
3110 palette[i].alpha = values[i ^ selector[1]][0];
3111 palette[i].red = values[i ^ selector[1]][1];
3112 palette[i].green = values[i ^ selector[1]][2];
3113 palette[i].blue = values[i ^ selector[1]][3];
3120 /* Initialize a standard palette on a write stream. The 'do_tRNS' argument
3121 * indicates whether or not to also set the tRNS chunk.
3123 /* TODO: the png_structp here can probably be 'const' in the future */
3125 init_standard_palette(png_store *ps, png_structp pp, png_infop pi, int npalette,
3128 store_palette_entry *ppal = make_standard_palette(ps, npalette, do_tRNS);
3132 png_color palette[256];
3134 /* Set all entries to detect overread errors. */
3135 for (i=0; i<npalette; ++i)
3137 palette[i].red = ppal[i].red;
3138 palette[i].green = ppal[i].green;
3139 palette[i].blue = ppal[i].blue;
3142 /* Just in case fill in the rest with detectable values: */
3144 palette[i].red = palette[i].green = palette[i].blue = 42;
3146 png_set_PLTE(pp, pi, palette, npalette);
3154 /* Set all the entries, but skip trailing opaque entries */
3155 for (i=j=0; i<npalette; ++i)
3156 if ((tRNS[i] = ppal[i].alpha) < 255)
3159 /* Fill in the remainder with a detectable value: */
3163 # ifdef PNG_WRITE_tRNS_SUPPORTED
3165 png_set_tRNS(pp, pi, tRNS, j, 0/*color*/);
3170 /* The number of passes is related to the interlace type. There was no libpng
3171 * API to determine this prior to 1.5, so we need an inquiry function:
3174 npasses_from_interlace_type(png_const_structp pp, int interlace_type)
3176 switch (interlace_type)
3179 png_error(pp, "invalid interlace type");
3181 case PNG_INTERLACE_NONE:
3184 case PNG_INTERLACE_ADAM7:
3185 return PNG_INTERLACE_ADAM7_PASSES;
3190 bit_size(png_const_structp pp, png_byte colour_type, png_byte bit_depth)
3192 switch (colour_type)
3194 default: png_error(pp, "invalid color type");
3196 case 0: return bit_depth;
3198 case 2: return 3*bit_depth;
3200 case 3: return bit_depth;
3202 case 4: return 2*bit_depth;
3204 case 6: return 4*bit_depth;
3208 #define TRANSFORM_WIDTH 128U
3209 #define TRANSFORM_ROWMAX (TRANSFORM_WIDTH*8U)
3210 #define SIZE_ROWMAX (16*8U) /* 16 pixels, max 8 bytes each - 128 bytes */
3211 #define STANDARD_ROWMAX TRANSFORM_ROWMAX /* The larger of the two */
3212 #define SIZE_HEIGHTMAX 16 /* Maximum range of size images */
3215 transform_rowsize(png_const_structp pp, png_byte colour_type,
3218 return (TRANSFORM_WIDTH * bit_size(pp, colour_type, bit_depth)) / 8;
3221 /* transform_width(pp, colour_type, bit_depth) current returns the same number
3222 * every time, so just use a macro:
3224 #define transform_width(pp, colour_type, bit_depth) TRANSFORM_WIDTH
3227 transform_height(png_const_structp pp, png_byte colour_type, png_byte bit_depth)
3229 switch (bit_size(pp, colour_type, bit_depth))
3234 return 1; /* Total of 128 pixels */
3237 return 2; /* Total of 256 pixels/bytes */
3240 return 512; /* Total of 65536 pixels */
3244 return 512; /* 65536 pixels */
3248 return 2048;/* 4 x 65536 pixels. */
3249 # define TRANSFORM_HEIGHTMAX 2048
3252 return 0; /* Error, will be caught later */
3256 #ifdef PNG_READ_SUPPORTED
3257 /* The following can only be defined here, now we have the definitions
3258 * of the transform image sizes.
3261 standard_width(png_const_structp pp, png_uint_32 id)
3263 png_uint_32 width = WIDTH_FROM_ID(id);
3267 width = transform_width(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
3273 standard_height(png_const_structp pp, png_uint_32 id)
3275 png_uint_32 height = HEIGHT_FROM_ID(id);
3278 height = transform_height(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
3284 standard_rowsize(png_const_structp pp, png_uint_32 id)
3286 png_uint_32 width = standard_width(pp, id);
3288 /* This won't overflow: */
3289 width *= bit_size(pp, COL_FROM_ID(id), DEPTH_FROM_ID(id));
3290 return (width + 7) / 8;
3292 #endif /* PNG_READ_SUPPORTED */
3295 transform_row(png_const_structp pp, png_byte buffer[TRANSFORM_ROWMAX],
3296 png_byte colour_type, png_byte bit_depth, png_uint_32 y)
3298 png_uint_32 v = y << 7;
3301 switch (bit_size(pp, colour_type, bit_depth))
3304 while (i<128/8) buffer[i] = (png_byte)(v & 0xff), v += 17, ++i;
3308 while (i<128/4) buffer[i] = (png_byte)(v & 0xff), v += 33, ++i;
3312 while (i<128/2) buffer[i] = (png_byte)(v & 0xff), v += 65, ++i;
3316 /* 256 bytes total, 128 bytes in each row set as follows: */
3317 while (i<128) buffer[i] = (png_byte)(v & 0xff), ++v, ++i;
3321 /* Generate all 65536 pixel values in order, which includes the 8 bit
3322 * GA case as well as the 16 bit G case.
3326 buffer[2*i] = (png_byte)((v>>8) & 0xff);
3327 buffer[2*i+1] = (png_byte)(v & 0xff);
3335 /* 65535 pixels, but rotate the values. */
3338 /* Three bytes per pixel, r, g, b, make b by r^g */
3339 buffer[3*i+0] = (png_byte)((v >> 8) & 0xff);
3340 buffer[3*i+1] = (png_byte)(v & 0xff);
3341 buffer[3*i+2] = (png_byte)(((v >> 8) ^ v) & 0xff);
3349 /* 65535 pixels, r, g, b, a; just replicate */
3352 buffer[4*i+0] = (png_byte)((v >> 8) & 0xff);
3353 buffer[4*i+1] = (png_byte)(v & 0xff);
3354 buffer[4*i+2] = (png_byte)((v >> 8) & 0xff);
3355 buffer[4*i+3] = (png_byte)(v & 0xff);
3363 /* y is maximum 2047, giving 4x65536 pixels, make 'r' increase by 1 at
3364 * each pixel, g increase by 257 (0x101) and 'b' by 0x1111:
3368 png_uint_32 t = v++;
3369 buffer[6*i+0] = (png_byte)((t >> 8) & 0xff);
3370 buffer[6*i+1] = (png_byte)(t & 0xff);
3372 buffer[6*i+2] = (png_byte)((t >> 8) & 0xff);
3373 buffer[6*i+3] = (png_byte)(t & 0xff);
3375 buffer[6*i+4] = (png_byte)((t >> 8) & 0xff);
3376 buffer[6*i+5] = (png_byte)(t & 0xff);
3383 /* As above in the 32 bit case. */
3386 png_uint_32 t = v++;
3387 buffer[8*i+0] = (png_byte)((t >> 8) & 0xff);
3388 buffer[8*i+1] = (png_byte)(t & 0xff);
3389 buffer[8*i+4] = (png_byte)((t >> 8) & 0xff);
3390 buffer[8*i+5] = (png_byte)(t & 0xff);
3392 buffer[8*i+2] = (png_byte)((t >> 8) & 0xff);
3393 buffer[8*i+3] = (png_byte)(t & 0xff);
3394 buffer[8*i+6] = (png_byte)((t >> 8) & 0xff);
3395 buffer[8*i+7] = (png_byte)(t & 0xff);
3404 png_error(pp, "internal error");
3407 /* This is just to do the right cast - could be changed to a function to check
3408 * 'bd' but there isn't much point.
3410 #define DEPTH(bd) ((png_byte)(1U << (bd)))
3412 /* This is just a helper for compiling on minimal systems with no write
3413 * interlacing support. If there is no write interlacing we can't generate test
3414 * cases with interlace:
3416 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
3417 # define INTERLACE_LAST PNG_INTERLACE_LAST
3418 # define check_interlace_type(type) ((void)(type))
3420 # define INTERLACE_LAST (PNG_INTERLACE_NONE+1)
3421 # define png_set_interlace_handling(a) (1)
3424 check_interlace_type(int PNG_CONST interlace_type)
3426 if (interlace_type != PNG_INTERLACE_NONE)
3428 /* This is an internal error - --interlace tests should be skipped, not
3431 fprintf(stderr, "pngvalid: no interlace support\n");
3437 /* Make a standardized image given a an image colour type, bit depth and
3438 * interlace type. The standard images have a very restricted range of
3439 * rows and heights and are used for testing transforms rather than image
3440 * layout details. See make_size_images below for a way to make images
3441 * that test odd sizes along with the libpng interlace handling.
3444 make_transform_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
3445 png_byte PNG_CONST bit_depth, unsigned int palette_number,
3446 int interlace_type, png_const_charp name)
3450 check_interlace_type(interlace_type);
3455 png_structp pp = set_store_for_write(ps, &pi, name);
3458 /* In the event of a problem return control to the Catch statement below
3459 * to do the clean up - it is not possible to 'return' directly from a Try
3465 h = transform_height(pp, colour_type, bit_depth);
3467 png_set_IHDR(pp, pi, transform_width(pp, colour_type, bit_depth), h,
3468 bit_depth, colour_type, interlace_type,
3469 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
3471 #ifdef PNG_TEXT_SUPPORTED
3472 # if defined(PNG_READ_zTXt_SUPPORTED) && defined(PNG_WRITE_zTXt_SUPPORTED)
3473 # define TEXT_COMPRESSION PNG_TEXT_COMPRESSION_zTXt
3475 # define TEXT_COMPRESSION PNG_TEXT_COMPRESSION_NONE
3478 static char key[] = "image name"; /* must be writeable */
3481 char copy[FILE_NAME_SIZE];
3483 /* Use a compressed text string to test the correct interaction of text
3484 * compression and IDAT compression.
3486 text.compression = TEXT_COMPRESSION;
3488 /* Yuck: the text must be writable! */
3489 pos = safecat(copy, sizeof copy, 0, ps->wname);
3491 text.text_length = pos;
3492 text.itxt_length = 0;
3496 png_set_text(pp, pi, &text, 1);
3500 if (colour_type == 3) /* palette */
3501 init_standard_palette(ps, pp, pi, 1U << bit_depth, 1/*do tRNS*/);
3503 png_write_info(pp, pi);
3505 if (png_get_rowbytes(pp, pi) !=
3506 transform_rowsize(pp, colour_type, bit_depth))
3507 png_error(pp, "row size incorrect");
3511 /* Somewhat confusingly this must be called *after* png_write_info
3512 * because if it is called before, the information in *pp has not been
3513 * updated to reflect the interlaced image.
3515 int npasses = png_set_interlace_handling(pp);
3518 if (npasses != npasses_from_interlace_type(pp, interlace_type))
3519 png_error(pp, "write: png_set_interlace_handling failed");
3521 for (pass=0; pass<npasses; ++pass)
3527 png_byte buffer[TRANSFORM_ROWMAX];
3529 transform_row(pp, buffer, colour_type, bit_depth, y);
3530 png_write_row(pp, buffer);
3535 #ifdef PNG_TEXT_SUPPORTED
3537 static char key[] = "end marker";
3538 static char comment[] = "end";
3541 /* Use a compressed text string to test the correct interaction of text
3542 * compression and IDAT compression.
3544 text.compression = TEXT_COMPRESSION;
3546 text.text = comment;
3547 text.text_length = (sizeof comment)-1;
3548 text.itxt_length = 0;
3552 png_set_text(pp, pi, &text, 1);
3556 png_write_end(pp, pi);
3558 /* And store this under the appropriate id, then clean up. */
3559 store_storefile(ps, FILEID(colour_type, bit_depth, palette_number,
3560 interlace_type, 0, 0, 0));
3562 store_write_reset(ps);
3567 /* Use the png_store returned by the exception. This may help the compiler
3568 * because 'ps' is not used in this branch of the setjmp. Note that fault
3569 * and ps will always be the same value.
3571 store_write_reset(fault);
3576 make_transform_images(png_store *ps)
3578 png_byte colour_type = 0;
3579 png_byte bit_depth = 0;
3580 unsigned int palette_number = 0;
3582 /* This is in case of errors. */
3583 safecat(ps->test, sizeof ps->test, 0, "make standard images");
3585 /* Use next_format to enumerate all the combinations we test, including
3586 * generating multiple low bit depth palette images.
3588 while (next_format(&colour_type, &bit_depth, &palette_number, 0))
3592 for (interlace_type = PNG_INTERLACE_NONE;
3593 interlace_type < INTERLACE_LAST; ++interlace_type)
3595 char name[FILE_NAME_SIZE];
3597 standard_name(name, sizeof name, 0, colour_type, bit_depth,
3598 palette_number, interlace_type, 0, 0, 0);
3599 make_transform_image(ps, colour_type, bit_depth, palette_number,
3600 interlace_type, name);
3605 /* The following two routines use the PNG interlace support macros from
3606 * png.h to interlace or deinterlace rows.
3609 interlace_row(png_bytep buffer, png_const_bytep imageRow,
3610 unsigned int pixel_size, png_uint_32 w, int pass)
3612 png_uint_32 xin, xout, xstep;
3614 /* Note that this can, trivially, be optimized to a memcpy on pass 7, the
3615 * code is presented this way to make it easier to understand. In practice
3616 * consult the code in the libpng source to see other ways of doing this.
3618 xin = PNG_PASS_START_COL(pass);
3619 xstep = 1U<<PNG_PASS_COL_SHIFT(pass);
3621 for (xout=0; xin<w; xin+=xstep)
3623 pixel_copy(buffer, xout, imageRow, xin, pixel_size);
3628 #ifdef PNG_READ_SUPPORTED
3630 deinterlace_row(png_bytep buffer, png_const_bytep row,
3631 unsigned int pixel_size, png_uint_32 w, int pass)
3633 /* The inverse of the above, 'row' is part of row 'y' of the output image,
3634 * in 'buffer'. The image is 'w' wide and this is pass 'pass', distribute
3635 * the pixels of row into buffer and return the number written (to allow
3636 * this to be checked).
3638 png_uint_32 xin, xout, xstep;
3640 xout = PNG_PASS_START_COL(pass);
3641 xstep = 1U<<PNG_PASS_COL_SHIFT(pass);
3643 for (xin=0; xout<w; xout+=xstep)
3645 pixel_copy(buffer, xout, row, xin, pixel_size);
3649 #endif /* PNG_READ_SUPPORTED */
3651 /* Build a single row for the 'size' test images; this fills in only the
3652 * first bit_width bits of the sample row.
3655 size_row(png_byte buffer[SIZE_ROWMAX], png_uint_32 bit_width, png_uint_32 y)
3657 /* height is in the range 1 to 16, so: */
3658 y = ((y & 1) << 7) + ((y & 2) << 6) + ((y & 4) << 5) + ((y & 8) << 4);
3659 /* the following ensures bits are set in small images: */
3662 while (bit_width >= 8)
3663 *buffer++ = (png_byte)y++, bit_width -= 8;
3665 /* There may be up to 7 remaining bits, these go in the most significant
3670 png_uint_32 mask = (1U<<(8-bit_width))-1;
3671 *buffer = (png_byte)((*buffer & mask) | (y & ~mask));
3676 make_size_image(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type,
3677 png_byte PNG_CONST bit_depth, int PNG_CONST interlace_type,
3678 png_uint_32 PNG_CONST w, png_uint_32 PNG_CONST h,
3679 int PNG_CONST do_interlace)
3683 /* At present libpng does not support the write of an interlaced image unless
3684 * PNG_WRITE_INTERLACING_SUPPORTED, even with do_interlace so the code here
3685 * does the pixel interlace itself, so:
3687 check_interlace_type(interlace_type);
3693 unsigned int pixel_size;
3695 /* Make a name and get an appropriate id for the store: */
3696 char name[FILE_NAME_SIZE];
3697 PNG_CONST png_uint_32 id = FILEID(colour_type, bit_depth, 0/*palette*/,
3698 interlace_type, w, h, do_interlace);
3700 standard_name_from_id(name, sizeof name, 0, id);
3701 pp = set_store_for_write(ps, &pi, name);
3703 /* In the event of a problem return control to the Catch statement below
3704 * to do the clean up - it is not possible to 'return' directly from a Try
3710 png_set_IHDR(pp, pi, w, h, bit_depth, colour_type, interlace_type,
3711 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
3713 #ifdef PNG_TEXT_SUPPORTED
3715 static char key[] = "image name"; /* must be writeable */
3718 char copy[FILE_NAME_SIZE];
3720 /* Use a compressed text string to test the correct interaction of text
3721 * compression and IDAT compression.
3723 text.compression = TEXT_COMPRESSION;
3725 /* Yuck: the text must be writable! */
3726 pos = safecat(copy, sizeof copy, 0, ps->wname);
3728 text.text_length = pos;
3729 text.itxt_length = 0;
3733 png_set_text(pp, pi, &text, 1);
3737 if (colour_type == 3) /* palette */
3738 init_standard_palette(ps, pp, pi, 1U << bit_depth, 0/*do tRNS*/);
3740 png_write_info(pp, pi);
3742 /* Calculate the bit size, divide by 8 to get the byte size - this won't
3743 * overflow because we know the w values are all small enough even for
3744 * a system where 'unsigned int' is only 16 bits.
3746 pixel_size = bit_size(pp, colour_type, bit_depth);
3747 if (png_get_rowbytes(pp, pi) != ((w * pixel_size) + 7) / 8)
3748 png_error(pp, "row size incorrect");
3752 int npasses = npasses_from_interlace_type(pp, interlace_type);
3755 # ifdef PNG_WRITE_FILTER_SUPPORTED
3756 int nfilter = PNG_FILTER_VALUE_LAST;
3758 png_byte image[16][SIZE_ROWMAX];
3760 /* To help consistent error detection make the parts of this buffer
3761 * that aren't set below all '1':
3763 memset(image, 0xff, sizeof image);
3765 if (!do_interlace && npasses != png_set_interlace_handling(pp))
3766 png_error(pp, "write: png_set_interlace_handling failed");
3768 /* Prepare the whole image first to avoid making it 7 times: */
3770 size_row(image[y], w * pixel_size, y);
3772 for (pass=0; pass<npasses; ++pass)
3774 /* The following two are for checking the macros: */
3775 PNG_CONST png_uint_32 wPass = PNG_PASS_COLS(w, pass);
3777 /* If do_interlace is set we don't call png_write_row for every
3778 * row because some of them are empty. In fact, for a 1x1 image,
3779 * most of them are empty!
3783 png_const_bytep row = image[y];
3784 png_byte tempRow[SIZE_ROWMAX];
3786 /* If do_interlace *and* the image is interlaced we
3787 * need a reduced interlace row; this may be reduced
3790 if (do_interlace && interlace_type == PNG_INTERLACE_ADAM7)
3792 /* The row must not be written if it doesn't exist, notice
3793 * that there are two conditions here, either the row isn't
3794 * ever in the pass or the row would be but isn't wide
3795 * enough to contribute any pixels. In fact the wPass test
3796 * can be used to skip the whole y loop in this case.
3798 if (PNG_ROW_IN_INTERLACE_PASS(y, pass) && wPass > 0)
3800 /* Set to all 1's for error detection (libpng tends to
3801 * set unset things to 0).
3803 memset(tempRow, 0xff, sizeof tempRow);
3804 interlace_row(tempRow, row, pixel_size, w, pass);
3811 # ifdef PNG_WRITE_FILTER_SUPPORTED
3812 /* Only get to here if the row has some pixels in it, set the
3813 * filters to 'all' for the very first row and thereafter to a
3814 * single filter. It isn't well documented, but png_set_filter
3815 * does accept a filter number (per the spec) as well as a bit
3818 * The apparent wackiness of decrementing nfilter rather than
3819 * incrementing is so that Paeth gets used in all images bigger
3820 * than 1 row - it's the tricky one.
3822 png_set_filter(pp, 0/*method*/,
3823 nfilter >= PNG_FILTER_VALUE_LAST ? PNG_ALL_FILTERS : nfilter);
3826 nfilter = PNG_FILTER_VALUE_LAST-1;
3829 png_write_row(pp, row);
3834 #ifdef PNG_TEXT_SUPPORTED
3836 static char key[] = "end marker";
3837 static char comment[] = "end";
3840 /* Use a compressed text string to test the correct interaction of text
3841 * compression and IDAT compression.
3843 text.compression = TEXT_COMPRESSION;
3845 text.text = comment;
3846 text.text_length = (sizeof comment)-1;
3847 text.itxt_length = 0;
3851 png_set_text(pp, pi, &text, 1);
3855 png_write_end(pp, pi);
3857 /* And store this under the appropriate id, then clean up. */
3858 store_storefile(ps, id);
3860 store_write_reset(ps);
3865 /* Use the png_store returned by the exception. This may help the compiler
3866 * because 'ps' is not used in this branch of the setjmp. Note that fault
3867 * and ps will always be the same value.
3869 store_write_reset(fault);
3874 make_size(png_store* PNG_CONST ps, png_byte PNG_CONST colour_type, int bdlo,
3877 for (; bdlo <= bdhi; ++bdlo)
3881 for (width = 1; width <= 16; ++width)
3885 for (height = 1; height <= 16; ++height)
3887 /* The four combinations of DIY interlace and interlace or not -
3888 * no interlace + DIY should be identical to no interlace with
3891 make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE,
3893 make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_NONE,
3895 # ifdef PNG_WRITE_INTERLACING_SUPPORTED
3896 make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7,
3898 make_size_image(ps, colour_type, DEPTH(bdlo), PNG_INTERLACE_ADAM7,
3907 make_size_images(png_store *ps)
3909 /* This is in case of errors. */
3910 safecat(ps->test, sizeof ps->test, 0, "make size images");
3912 /* Arguments are colour_type, low bit depth, high bit depth
3914 make_size(ps, 0, 0, WRITE_BDHI);
3915 make_size(ps, 2, 3, WRITE_BDHI);
3916 make_size(ps, 3, 0, 3 /*palette: max 8 bits*/);
3917 make_size(ps, 4, 3, WRITE_BDHI);
3918 make_size(ps, 6, 3, WRITE_BDHI);
3921 #ifdef PNG_READ_SUPPORTED
3922 /* Return a row based on image id and 'y' for checking: */
3924 standard_row(png_const_structp pp, png_byte std[STANDARD_ROWMAX],
3925 png_uint_32 id, png_uint_32 y)
3927 if (WIDTH_FROM_ID(id) == 0)
3928 transform_row(pp, std, COL_FROM_ID(id), DEPTH_FROM_ID(id), y);
3930 size_row(std, WIDTH_FROM_ID(id) * bit_size(pp, COL_FROM_ID(id),
3931 DEPTH_FROM_ID(id)), y);
3933 #endif /* PNG_READ_SUPPORTED */
3935 /* Tests - individual test cases */
3936 /* Like 'make_standard' but errors are deliberately introduced into the calls
3937 * to ensure that they get detected - it should not be possible to write an
3938 * invalid image with libpng!
3940 /* TODO: the 'set' functions can probably all be made to take a
3941 * png_const_structp rather than a modifiable one.
3943 #ifdef PNG_WARNINGS_SUPPORTED
3945 sBIT0_error_fn(png_structp pp, png_infop pi)
3947 /* 0 is invalid... */
3949 bad.red = bad.green = bad.blue = bad.gray = bad.alpha = 0;
3950 png_set_sBIT(pp, pi, &bad);
3954 sBIT_error_fn(png_structp pp, png_infop pi)
3959 if (png_get_color_type(pp, pi) == PNG_COLOR_TYPE_PALETTE)
3963 bit_depth = png_get_bit_depth(pp, pi);
3965 /* Now we know the bit depth we can easily generate an invalid sBIT entry */
3966 bad.red = bad.green = bad.blue = bad.gray = bad.alpha =
3967 (png_byte)(bit_depth+1);
3968 png_set_sBIT(pp, pi, &bad);
3971 static PNG_CONST struct
3973 void (*fn)(png_structp, png_infop);
3974 PNG_CONST char *msg;
3975 unsigned int warning :1; /* the error is a warning... */
3978 /* no warnings makes these errors undetectable. */
3979 { sBIT0_error_fn, "sBIT(0): failed to detect error", 1 },
3980 { sBIT_error_fn, "sBIT(too big): failed to detect error", 1 },
3984 make_error(png_store* volatile psIn, png_byte PNG_CONST colour_type,
3985 png_byte bit_depth, int interlace_type, int test, png_const_charp name)
3987 png_store * volatile ps = psIn;
3991 check_interlace_type(interlace_type);
3998 pp = set_store_for_write(ps, &pi, name);
4003 png_set_IHDR(pp, pi, transform_width(pp, colour_type, bit_depth),
4004 transform_height(pp, colour_type, bit_depth), bit_depth, colour_type,
4005 interlace_type, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
4007 if (colour_type == 3) /* palette */
4008 init_standard_palette(ps, pp, pi, 1U << bit_depth, 0/*do tRNS*/);
4010 /* Time for a few errors; these are in various optional chunks, the
4011 * standard tests test the standard chunks pretty well.
4013 # define exception__prev exception_prev_1
4014 # define exception__env exception_env_1
4017 /* Expect this to throw: */
4018 ps->expect_error = !error_test[test].warning;
4019 ps->expect_warning = error_test[test].warning;
4020 ps->saw_warning = 0;
4021 error_test[test].fn(pp, pi);
4023 /* Normally the error is only detected here: */
4024 png_write_info(pp, pi);
4026 /* And handle the case where it was only a warning: */
4027 if (ps->expect_warning && ps->saw_warning)
4030 /* If we get here there is a problem, we have success - no error or
4031 * no warning - when we shouldn't have success. Log an error.
4033 store_log(ps, pp, error_test[test].msg, 1 /*error*/);
4037 ps = fault; /* expected exit, make sure ps is not clobbered */
4038 #undef exception__prev
4039 #undef exception__env
4041 /* And clear these flags */
4042 ps->expect_error = 0;
4043 ps->expect_warning = 0;
4045 /* Now write the whole image, just to make sure that the detected, or
4046 * undetected, errro has not created problems inside libpng.
4048 if (png_get_rowbytes(pp, pi) !=
4049 transform_rowsize(pp, colour_type, bit_depth))
4050 png_error(pp, "row size incorrect");
4054 png_uint_32 h = transform_height(pp, colour_type, bit_depth);
4055 int npasses = png_set_interlace_handling(pp);
4058 if (npasses != npasses_from_interlace_type(pp, interlace_type))
4059 png_error(pp, "write: png_set_interlace_handling failed");
4061 for (pass=0; pass<npasses; ++pass)
4067 png_byte buffer[TRANSFORM_ROWMAX];
4069 transform_row(pp, buffer, colour_type, bit_depth, y);
4070 png_write_row(pp, buffer);
4075 png_write_end(pp, pi);
4077 /* The following deletes the file that was just written. */
4078 store_write_reset(ps);
4083 store_write_reset(fault);
4088 make_errors(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
4089 int bdlo, int PNG_CONST bdhi)
4091 for (; bdlo <= bdhi; ++bdlo)
4095 for (interlace_type = PNG_INTERLACE_NONE;
4096 interlace_type < INTERLACE_LAST; ++interlace_type)
4099 char name[FILE_NAME_SIZE];
4101 standard_name(name, sizeof name, 0, colour_type, 1<<bdlo, 0,
4102 interlace_type, 0, 0, 0);
4104 for (test=0; test<(sizeof error_test)/(sizeof error_test[0]); ++test)
4106 make_error(&pm->this, colour_type, DEPTH(bdlo), interlace_type,
4115 return 1; /* keep going */
4117 #endif /* PNG_WARNINGS_SUPPORTED */
4120 perform_error_test(png_modifier *pm)
4122 #ifdef PNG_WARNINGS_SUPPORTED /* else there are no cases that work! */
4123 /* Need to do this here because we just write in this test. */
4124 safecat(pm->this.test, sizeof pm->this.test, 0, "error test");
4126 if (!make_errors(pm, 0, 0, WRITE_BDHI))
4129 if (!make_errors(pm, 2, 3, WRITE_BDHI))
4132 if (!make_errors(pm, 3, 0, 3))
4135 if (!make_errors(pm, 4, 3, WRITE_BDHI))
4138 if (!make_errors(pm, 6, 3, WRITE_BDHI))
4145 /* This is just to validate the internal PNG formatting code - if this fails
4146 * then the warning messages the library outputs will probably be garbage.
4149 perform_formatting_test(png_store *volatile ps)
4151 #ifdef PNG_TIME_RFC1123_SUPPORTED
4152 /* The handle into the formatting code is the RFC1123 support; this test does
4153 * nothing if that is compiled out.
4159 png_const_charp correct = "29 Aug 2079 13:53:60 +0000";
4160 png_const_charp result;
4161 # if PNG_LIBPNG_VER >= 10600
4162 char timestring[29];
4167 pp = set_store_for_write(ps, NULL, "libpng formatting test");
4173 /* Arbitrary settings: */
4179 pt.second = 60; /* a leap second */
4181 # if PNG_LIBPNG_VER < 10600
4182 result = png_convert_to_rfc1123(pp, &pt);
4184 if (png_convert_to_rfc1123_buffer(timestring, &pt))
4185 result = timestring;
4192 png_error(pp, "png_convert_to_rfc1123 failed");
4194 if (strcmp(result, correct) != 0)
4199 pos = safecat(msg, sizeof msg, pos, "png_convert_to_rfc1123(");
4200 pos = safecat(msg, sizeof msg, pos, correct);
4201 pos = safecat(msg, sizeof msg, pos, ") returned: '");
4202 pos = safecat(msg, sizeof msg, pos, result);
4203 pos = safecat(msg, sizeof msg, pos, "'");
4208 store_write_reset(ps);
4213 store_write_reset(fault);
4220 #ifdef PNG_READ_SUPPORTED
4221 /* Because we want to use the same code in both the progressive reader and the
4222 * sequential reader it is necessary to deal with the fact that the progressive
4223 * reader callbacks only have one parameter (png_get_progressive_ptr()), so this
4224 * must contain all the test parameters and all the local variables directly
4225 * accessible to the sequential reader implementation.
4227 * The technique adopted is to reinvent part of what Dijkstra termed a
4228 * 'display'; an array of pointers to the stack frames of enclosing functions so
4229 * that a nested function definition can access the local (C auto) variables of
4230 * the functions that contain its definition. In fact C provides the first
4231 * pointer (the local variables - the stack frame pointer) and the last (the
4232 * global variables - the BCPL global vector typically implemented as global
4233 * addresses), this code requires one more pointer to make the display - the
4234 * local variables (and function call parameters) of the function that actually
4235 * invokes either the progressive or sequential reader.
4237 * Perhaps confusingly this technique is confounded with classes - the
4238 * 'standard_display' defined here is sub-classed as the 'gamma_display' below.
4239 * A gamma_display is a standard_display, taking advantage of the ANSI-C
4240 * requirement that the pointer to the first member of a structure must be the
4241 * same as the pointer to the structure. This allows us to reuse standard_
4242 * functions in the gamma test code; something that could not be done with
4245 typedef struct standard_display
4247 png_store* ps; /* Test parameters (passed to the function) */
4248 png_byte colour_type;
4250 png_byte red_sBIT; /* Input data sBIT values. */
4251 png_byte green_sBIT;
4253 png_byte alpha_sBIT;
4255 png_uint_32 id; /* Calculated file ID */
4256 png_uint_32 w; /* Width of image */
4257 png_uint_32 h; /* Height of image */
4258 int npasses; /* Number of interlaced passes */
4259 png_uint_32 pixel_size; /* Width of one pixel in bits */
4260 png_uint_32 bit_width; /* Width of output row in bits */
4261 size_t cbRow; /* Bytes in a row of the output image */
4262 int do_interlace; /* Do interlacing internally */
4263 int is_transparent; /* Transparency information was present. */
4264 int speed; /* Doing a speed test */
4265 int use_update_info;/* Call update_info, not start_image */
4271 } transparent; /* The transparent color, if set. */
4272 int npalette; /* Number of entries in the palette. */
4278 standard_display_init(standard_display *dp, png_store* ps, png_uint_32 id,
4279 int do_interlace, int use_update_info)
4281 memset(dp, 0, sizeof *dp);
4284 dp->colour_type = COL_FROM_ID(id);
4285 dp->bit_depth = DEPTH_FROM_ID(id);
4286 if (dp->bit_depth < 1 || dp->bit_depth > 16)
4287 internal_error(ps, "internal: bad bit depth");
4288 if (dp->colour_type == 3)
4289 dp->red_sBIT = dp->blue_sBIT = dp->green_sBIT = dp->alpha_sBIT = 8;
4291 dp->red_sBIT = dp->blue_sBIT = dp->green_sBIT = dp->alpha_sBIT =
4293 dp->interlace_type = INTERLACE_FROM_ID(id);
4294 check_interlace_type(dp->interlace_type);
4296 /* All the rest are filled in after the read_info: */
4303 dp->do_interlace = do_interlace;
4304 dp->is_transparent = 0;
4305 dp->speed = ps->speed;
4306 dp->use_update_info = use_update_info;
4308 /* Preset the transparent color to black: */
4309 memset(&dp->transparent, 0, sizeof dp->transparent);
4310 /* Preset the palette to full intensity/opaque througout: */
4311 memset(dp->palette, 0xff, sizeof dp->palette);
4314 /* Initialize the palette fields - this must be done later because the palette
4315 * comes from the particular png_store_file that is selected.
4318 standard_palette_init(standard_display *dp)
4320 store_palette_entry *palette = store_current_palette(dp->ps, &dp->npalette);
4322 /* The remaining entries remain white/opaque. */
4323 if (dp->npalette > 0)
4325 int i = dp->npalette;
4326 memcpy(dp->palette, palette, i * sizeof *palette);
4328 /* Check for a non-opaque palette entry: */
4330 if (palette[i].alpha < 255)
4334 /* GCC can't handle the more obviously optimizable version. */
4336 dp->is_transparent = 1;
4338 dp->is_transparent = 0;
4340 dp->is_transparent = (i >= 0);
4345 /* Utility to read the palette from the PNG file and convert it into
4346 * store_palette format. This returns 1 if there is any transparency in the
4347 * palette (it does not check for a transparent colour in the non-palette case.)
4350 read_palette(store_palette palette, int *npalette, png_const_structp pp,
4354 png_bytep trans_alpha;
4360 if (png_get_PLTE(pp, pi, &pal, npalette) & PNG_INFO_PLTE)
4364 if (i <= 0 || i > 256)
4365 png_error(pp, "validate: invalid PLTE count");
4369 palette[i].red = pal[i].red;
4370 palette[i].green = pal[i].green;
4371 palette[i].blue = pal[i].blue;
4374 /* Mark the remainder of the entries with a flag value (other than
4375 * white/opaque which is the flag value stored above.)
4377 memset(palette + *npalette, 126, (256-*npalette) * sizeof *palette);
4380 else /* !png_get_PLTE */
4382 if (*npalette != (-1))
4383 png_error(pp, "validate: invalid PLTE result");
4384 /* But there is no palette, so record this: */
4386 memset(palette, 113, sizeof (store_palette));
4390 num = 2; /* force error below */
4391 if ((png_get_tRNS(pp, pi, &trans_alpha, &num, 0) & PNG_INFO_tRNS) != 0 &&
4392 (trans_alpha != NULL || num != 1/*returns 1 for a transparent color*/) &&
4393 /* Oops, if a palette tRNS gets expanded png_read_update_info (at least so
4394 * far as 1.5.4) does not remove the trans_alpha pointer, only num_trans,
4395 * so in the above call we get a success, we get a pointer (who knows what
4396 * to) and we get num_trans == 0:
4398 !(trans_alpha != NULL && num == 0)) /* TODO: fix this in libpng. */
4402 /* Any of these are crash-worthy - given the implementation of
4403 * png_get_tRNS up to 1.5 an app won't crash if it just checks the
4404 * result above and fails to check that the variables it passed have
4405 * actually been filled in! Note that if the app were to pass the
4406 * last, png_color_16p, variable too it couldn't rely on this.
4408 if (trans_alpha == NULL || num <= 0 || num > 256 || num > *npalette)
4409 png_error(pp, "validate: unexpected png_get_tRNS (palette) result");
4411 for (i=0; i<num; ++i)
4412 palette[i].alpha = trans_alpha[i];
4414 for (num=*npalette; i<num; ++i)
4415 palette[i].alpha = 255;
4418 palette[i].alpha = 33; /* flag value */
4420 return 1; /* transparency */
4425 /* No palette transparency - just set the alpha channel to opaque. */
4428 for (i=0, num=*npalette; i<num; ++i)
4429 palette[i].alpha = 255;
4432 palette[i].alpha = 55; /* flag value */
4434 return 0; /* no transparency */
4438 /* Utility to validate the palette if it should not have changed (the
4439 * non-transform case).
4442 standard_palette_validate(standard_display *dp, png_const_structp pp,
4446 store_palette palette;
4448 if (read_palette(palette, &npalette, pp, pi) != dp->is_transparent)
4449 png_error(pp, "validate: palette transparency changed");
4451 if (npalette != dp->npalette)
4456 pos = safecat(msg, sizeof msg, pos, "validate: palette size changed: ");
4457 pos = safecatn(msg, sizeof msg, pos, dp->npalette);
4458 pos = safecat(msg, sizeof msg, pos, " -> ");
4459 pos = safecatn(msg, sizeof msg, pos, npalette);
4464 int i = npalette; /* npalette is aliased */
4467 if (palette[i].red != dp->palette[i].red ||
4468 palette[i].green != dp->palette[i].green ||
4469 palette[i].blue != dp->palette[i].blue ||
4470 palette[i].alpha != dp->palette[i].alpha)
4471 png_error(pp, "validate: PLTE or tRNS chunk changed");
4475 /* By passing a 'standard_display' the progressive callbacks can be used
4476 * directly by the sequential code, the functions suffixed "_imp" are the
4477 * implementations, the functions without the suffix are the callbacks.
4479 * The code for the info callback is split into two because this callback calls
4480 * png_read_update_info or png_start_read_image and what gets called depends on
4481 * whether the info needs updating (we want to test both calls in pngvalid.)
4484 standard_info_part1(standard_display *dp, png_structp pp, png_infop pi)
4486 if (png_get_bit_depth(pp, pi) != dp->bit_depth)
4487 png_error(pp, "validate: bit depth changed");
4489 if (png_get_color_type(pp, pi) != dp->colour_type)
4490 png_error(pp, "validate: color type changed");
4492 if (png_get_filter_type(pp, pi) != PNG_FILTER_TYPE_BASE)
4493 png_error(pp, "validate: filter type changed");
4495 if (png_get_interlace_type(pp, pi) != dp->interlace_type)
4496 png_error(pp, "validate: interlacing changed");
4498 if (png_get_compression_type(pp, pi) != PNG_COMPRESSION_TYPE_BASE)
4499 png_error(pp, "validate: compression type changed");
4501 dp->w = png_get_image_width(pp, pi);
4503 if (dp->w != standard_width(pp, dp->id))
4504 png_error(pp, "validate: image width changed");
4506 dp->h = png_get_image_height(pp, pi);
4508 if (dp->h != standard_height(pp, dp->id))
4509 png_error(pp, "validate: image height changed");
4511 /* Record (but don't check at present) the input sBIT according to the colour
4515 png_color_8p sBIT = 0;
4517 if (png_get_sBIT(pp, pi, &sBIT) & PNG_INFO_sBIT)
4519 int sBIT_invalid = 0;
4522 png_error(pp, "validate: unexpected png_get_sBIT result");
4524 if (dp->colour_type & PNG_COLOR_MASK_COLOR)
4526 if (sBIT->red == 0 || sBIT->red > dp->bit_depth)
4529 dp->red_sBIT = sBIT->red;
4531 if (sBIT->green == 0 || sBIT->green > dp->bit_depth)
4534 dp->green_sBIT = sBIT->green;
4536 if (sBIT->blue == 0 || sBIT->blue > dp->bit_depth)
4539 dp->blue_sBIT = sBIT->blue;
4544 if (sBIT->gray == 0 || sBIT->gray > dp->bit_depth)
4547 dp->blue_sBIT = dp->green_sBIT = dp->red_sBIT = sBIT->gray;
4550 /* All 8 bits in tRNS for a palette image are significant - see the
4553 if (dp->colour_type & PNG_COLOR_MASK_ALPHA)
4555 if (sBIT->alpha == 0 || sBIT->alpha > dp->bit_depth)
4558 dp->alpha_sBIT = sBIT->alpha;
4562 png_error(pp, "validate: sBIT value out of range");
4566 /* Important: this is validating the value *before* any transforms have been
4567 * put in place. It doesn't matter for the standard tests, where there are
4568 * no transforms, but it does for other tests where rowbytes may change after
4569 * png_read_update_info.
4571 if (png_get_rowbytes(pp, pi) != standard_rowsize(pp, dp->id))
4572 png_error(pp, "validate: row size changed");
4574 /* Validate the colour type 3 palette (this can be present on other color
4577 standard_palette_validate(dp, pp, pi);
4579 /* In any case always check for a tranparent color (notice that the
4580 * colour type 3 case must not give a successful return on the get_tRNS call
4581 * with these arguments!)
4584 png_color_16p trans_color = 0;
4586 if (png_get_tRNS(pp, pi, 0, 0, &trans_color) & PNG_INFO_tRNS)
4588 if (trans_color == 0)
4589 png_error(pp, "validate: unexpected png_get_tRNS (color) result");
4591 switch (dp->colour_type)
4594 dp->transparent.red = dp->transparent.green = dp->transparent.blue =
4596 dp->is_transparent = 1;
4600 dp->transparent.red = trans_color->red;
4601 dp->transparent.green = trans_color->green;
4602 dp->transparent.blue = trans_color->blue;
4603 dp->is_transparent = 1;
4607 /* Not expected because it should result in the array case
4610 png_error(pp, "validate: unexpected png_get_tRNS result");
4614 png_error(pp, "validate: invalid tRNS chunk with alpha image");
4619 /* Read the number of passes - expected to match the value used when
4620 * creating the image (interlaced or not). This has the side effect of
4621 * turning on interlace handling (if do_interlace is not set.)
4623 dp->npasses = npasses_from_interlace_type(pp, dp->interlace_type);
4624 if (!dp->do_interlace && dp->npasses != png_set_interlace_handling(pp))
4625 png_error(pp, "validate: file changed interlace type");
4627 /* Caller calls png_read_update_info or png_start_read_image now, then calls
4632 /* This must be called *after* the png_read_update_info call to get the correct
4633 * 'rowbytes' value, otherwise png_get_rowbytes will refer to the untransformed
4637 standard_info_part2(standard_display *dp, png_const_structp pp,
4638 png_const_infop pi, int nImages)
4640 /* Record cbRow now that it can be found. */
4641 dp->pixel_size = bit_size(pp, png_get_color_type(pp, pi),
4642 png_get_bit_depth(pp, pi));
4643 dp->bit_width = png_get_image_width(pp, pi) * dp->pixel_size;
4644 dp->cbRow = png_get_rowbytes(pp, pi);
4646 /* Validate the rowbytes here again. */
4647 if (dp->cbRow != (dp->bit_width+7)/8)
4648 png_error(pp, "bad png_get_rowbytes calculation");
4650 /* Then ensure there is enough space for the output image(s). */
4651 store_ensure_image(dp->ps, pp, nImages, dp->cbRow, dp->h);
4655 standard_info_imp(standard_display *dp, png_structp pp, png_infop pi,
4658 /* Note that the validation routine has the side effect of turning on
4659 * interlace handling in the subsequent code.
4661 standard_info_part1(dp, pp, pi);
4663 /* And the info callback has to call this (or png_read_update_info - see
4664 * below in the png_modifier code for that variant.
4666 if (dp->use_update_info)
4668 /* For debugging the effect of multiple calls: */
4669 int i = dp->use_update_info;
4671 png_read_update_info(pp, pi);
4675 png_start_read_image(pp);
4677 /* Validate the height, width and rowbytes plus ensure that sufficient buffer
4678 * exists for decoding the image.
4680 standard_info_part2(dp, pp, pi, nImages);
4683 static void PNGCBAPI
4684 standard_info(png_structp pp, png_infop pi)
4686 standard_display *dp = voidcast(standard_display*,
4687 png_get_progressive_ptr(pp));
4689 /* Call with nImages==1 because the progressive reader can only produce one
4692 standard_info_imp(dp, pp, pi, 1 /*only one image*/);
4695 static void PNGCBAPI
4696 progressive_row(png_structp ppIn, png_bytep new_row, png_uint_32 y, int pass)
4698 png_const_structp pp = ppIn;
4699 PNG_CONST standard_display *dp = voidcast(standard_display*,
4700 png_get_progressive_ptr(pp));
4702 /* When handling interlacing some rows will be absent in each pass, the
4703 * callback still gets called, but with a NULL pointer. This is checked
4704 * in the 'else' clause below. We need our own 'cbRow', but we can't call
4705 * png_get_rowbytes because we got no info structure.
4707 if (new_row != NULL)
4711 /* In the case where the reader doesn't do the interlace it gives
4712 * us the y in the sub-image:
4714 if (dp->do_interlace && dp->interlace_type == PNG_INTERLACE_ADAM7)
4716 #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
4717 /* Use this opportunity to validate the png 'current' APIs: */
4718 if (y != png_get_current_row_number(pp))
4719 png_error(pp, "png_get_current_row_number is broken");
4721 if (pass != png_get_current_pass_number(pp))
4722 png_error(pp, "png_get_current_pass_number is broken");
4725 y = PNG_ROW_FROM_PASS_ROW(y, pass);
4728 /* Validate this just in case. */
4730 png_error(pp, "invalid y to progressive row callback");
4732 row = store_image_row(dp->ps, pp, 0, y);
4734 #ifdef PNG_READ_INTERLACING_SUPPORTED
4735 /* Combine the new row into the old: */
4736 if (dp->do_interlace)
4738 if (dp->interlace_type == PNG_INTERLACE_ADAM7)
4739 deinterlace_row(row, new_row, dp->pixel_size, dp->w, pass);
4741 row_copy(row, new_row, dp->pixel_size * dp->w);
4744 png_progressive_combine_row(pp, row, new_row);
4745 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4748 #ifdef PNG_READ_INTERLACING_SUPPORTED
4749 else if (dp->interlace_type == PNG_INTERLACE_ADAM7 &&
4750 PNG_ROW_IN_INTERLACE_PASS(y, pass) &&
4751 PNG_PASS_COLS(dp->w, pass) > 0)
4752 png_error(pp, "missing row in progressive de-interlacing");
4753 #endif /* PNG_READ_INTERLACING_SUPPORTED */
4757 sequential_row(standard_display *dp, png_structp pp, png_infop pi,
4758 PNG_CONST int iImage, PNG_CONST int iDisplay)
4760 PNG_CONST int npasses = dp->npasses;
4761 PNG_CONST int do_interlace = dp->do_interlace &&
4762 dp->interlace_type == PNG_INTERLACE_ADAM7;
4763 PNG_CONST png_uint_32 height = standard_height(pp, dp->id);
4764 PNG_CONST png_uint_32 width = standard_width(pp, dp->id);
4765 PNG_CONST png_store* ps = dp->ps;
4768 for (pass=0; pass<npasses; ++pass)
4771 png_uint_32 wPass = PNG_PASS_COLS(width, pass);
4773 for (y=0; y<height; ++y)
4777 /* wPass may be zero or this row may not be in this pass.
4778 * png_read_row must not be called in either case.
4780 if (wPass > 0 && PNG_ROW_IN_INTERLACE_PASS(y, pass))
4782 /* Read the row into a pair of temporary buffers, then do the
4783 * merge here into the output rows.
4785 png_byte row[STANDARD_ROWMAX], display[STANDARD_ROWMAX];
4787 /* The following aids (to some extent) error detection - we can
4788 * see where png_read_row wrote. Use opposite values in row and
4789 * display to make this easier. Don't use 0xff (which is used in
4790 * the image write code to fill unused bits) or 0 (which is a
4791 * likely value to overwrite unused bits with).
4793 memset(row, 0xc5, sizeof row);
4794 memset(display, 0x5c, sizeof display);
4796 png_read_row(pp, row, display);
4799 deinterlace_row(store_image_row(ps, pp, iImage, y), row,
4800 dp->pixel_size, dp->w, pass);
4803 deinterlace_row(store_image_row(ps, pp, iDisplay, y), display,
4804 dp->pixel_size, dp->w, pass);
4809 iImage >= 0 ? store_image_row(ps, pp, iImage, y) : NULL,
4810 iDisplay >= 0 ? store_image_row(ps, pp, iDisplay, y) : NULL);
4814 /* And finish the read operation (only really necessary if the caller wants
4815 * to find additional data in png_info from chunks after the last IDAT.)
4817 png_read_end(pp, pi);
4820 #ifdef PNG_TEXT_SUPPORTED
4822 standard_check_text(png_const_structp pp, png_const_textp tp,
4823 png_const_charp keyword, png_const_charp text)
4826 size_t pos = safecat(msg, sizeof msg, 0, "text: ");
4829 pos = safecat(msg, sizeof msg, pos, keyword);
4830 pos = safecat(msg, sizeof msg, pos, ": ");
4833 if (tp->compression != TEXT_COMPRESSION)
4837 sprintf(buf, "compression [%d->%d], ", TEXT_COMPRESSION,
4839 pos = safecat(msg, sizeof msg, pos, buf);
4842 if (tp->key == NULL || strcmp(tp->key, keyword) != 0)
4844 pos = safecat(msg, sizeof msg, pos, "keyword \"");
4845 if (tp->key != NULL)
4847 pos = safecat(msg, sizeof msg, pos, tp->key);
4848 pos = safecat(msg, sizeof msg, pos, "\", ");
4852 pos = safecat(msg, sizeof msg, pos, "null, ");
4855 if (tp->text == NULL)
4856 pos = safecat(msg, sizeof msg, pos, "text lost, ");
4860 if (tp->text_length != strlen(text))
4863 sprintf(buf, "text length changed[%lu->%lu], ",
4864 (unsigned long)strlen(text), (unsigned long)tp->text_length);
4865 pos = safecat(msg, sizeof msg, pos, buf);
4868 if (strcmp(tp->text, text) != 0)
4870 pos = safecat(msg, sizeof msg, pos, "text becomes \"");
4871 pos = safecat(msg, sizeof msg, pos, tp->text);
4872 pos = safecat(msg, sizeof msg, pos, "\" (was \"");
4873 pos = safecat(msg, sizeof msg, pos, text);
4874 pos = safecat(msg, sizeof msg, pos, "\"), ");
4878 if (tp->itxt_length != 0)
4879 pos = safecat(msg, sizeof msg, pos, "iTXt length set, ");
4881 if (tp->lang != NULL)
4883 pos = safecat(msg, sizeof msg, pos, "iTXt language \"");
4884 pos = safecat(msg, sizeof msg, pos, tp->lang);
4885 pos = safecat(msg, sizeof msg, pos, "\", ");
4888 if (tp->lang_key != NULL)
4890 pos = safecat(msg, sizeof msg, pos, "iTXt keyword \"");
4891 pos = safecat(msg, sizeof msg, pos, tp->lang_key);
4892 pos = safecat(msg, sizeof msg, pos, "\", ");
4897 msg[pos-2] = '\0'; /* Remove the ", " at the end */
4903 standard_text_validate(standard_display *dp, png_const_structp pp,
4904 png_infop pi, int check_end)
4906 png_textp tp = NULL;
4907 png_uint_32 num_text = png_get_text(pp, pi, &tp, NULL);
4909 if (num_text == 2 && tp != NULL)
4911 standard_check_text(pp, tp, "image name", dp->ps->current->name);
4913 /* This exists because prior to 1.5.18 the progressive reader left the
4914 * png_struct z_stream unreset at the end of the image, so subsequent
4915 * attempts to use it simply returns Z_STREAM_END.
4918 standard_check_text(pp, tp+1, "end marker", "end");
4925 sprintf(msg, "expected two text items, got %lu",
4926 (unsigned long)num_text);
4931 # define standard_text_validate(dp,pp,pi,check_end) ((void)0)
4935 standard_row_validate(standard_display *dp, png_const_structp pp,
4936 int iImage, int iDisplay, png_uint_32 y)
4939 png_byte std[STANDARD_ROWMAX];
4941 /* The row must be pre-initialized to the magic number here for the size
4944 memset(std, 178, sizeof std);
4945 standard_row(pp, std, dp->id, y);
4947 /* At the end both the 'row' and 'display' arrays should end up identical.
4948 * In earlier passes 'row' will be partially filled in, with only the pixels
4949 * that have been read so far, but 'display' will have those pixels
4950 * replicated to fill the unread pixels while reading an interlaced image.
4951 #if PNG_LIBPNG_VER < 10506
4952 * The side effect inside the libpng sequential reader is that the 'row'
4953 * array retains the correct values for unwritten pixels within the row
4954 * bytes, while the 'display' array gets bits off the end of the image (in
4955 * the last byte) trashed. Unfortunately in the progressive reader the
4956 * row bytes are always trashed, so we always do a pixel_cmp here even though
4957 * a memcmp of all cbRow bytes will succeed for the sequential reader.
4961 (where = pixel_cmp(std, store_image_row(dp->ps, pp, iImage, y),
4962 dp->bit_width)) != 0)
4965 sprintf(msg, "PNG image row[%lu][%d] changed from %.2x to %.2x",
4966 (unsigned long)y, where-1, std[where-1],
4967 store_image_row(dp->ps, pp, iImage, y)[where-1]);
4971 #if PNG_LIBPNG_VER < 10506
4972 /* In this case use pixel_cmp because we need to compare a partial
4973 * byte at the end of the row if the row is not an exact multiple
4974 * of 8 bits wide. (This is fixed in libpng-1.5.6 and pixel_cmp is
4975 * changed to match!)
4978 if (iDisplay >= 0 &&
4979 (where = pixel_cmp(std, store_image_row(dp->ps, pp, iDisplay, y),
4980 dp->bit_width)) != 0)
4983 sprintf(msg, "display row[%lu][%d] changed from %.2x to %.2x",
4984 (unsigned long)y, where-1, std[where-1],
4985 store_image_row(dp->ps, pp, iDisplay, y)[where-1]);
4991 standard_image_validate(standard_display *dp, png_const_structp pp, int iImage,
4997 store_image_check(dp->ps, pp, iImage);
5000 store_image_check(dp->ps, pp, iDisplay);
5002 for (y=0; y<dp->h; ++y)
5003 standard_row_validate(dp, pp, iImage, iDisplay, y);
5005 /* This avoids false positives if the validation code is never called! */
5006 dp->ps->validated = 1;
5009 static void PNGCBAPI
5010 standard_end(png_structp ppIn, png_infop pi)
5012 png_const_structp pp = ppIn;
5013 standard_display *dp = voidcast(standard_display*,
5014 png_get_progressive_ptr(pp));
5018 /* Validate the image - progressive reading only produces one variant for
5019 * interlaced images.
5021 standard_text_validate(dp, pp, pi,
5022 PNG_LIBPNG_VER >= 10518/*check_end: see comments above*/);
5023 standard_image_validate(dp, pp, 0, -1);
5026 /* A single test run checking the standard image to ensure it is not damaged. */
5028 standard_test(png_store* PNG_CONST psIn, png_uint_32 PNG_CONST id,
5029 int do_interlace, int use_update_info)
5032 context(psIn, fault);
5034 /* Set up the display (stack frame) variables from the arguments to the
5035 * function and initialize the locals that are filled in later.
5037 standard_display_init(&d, psIn, id, do_interlace, use_update_info);
5039 /* Everything is protected by a Try/Catch. The functions called also
5040 * typically have local Try/Catch blocks.
5047 /* Get a png_struct for reading the image. This will throw an error if it
5048 * fails, so we don't need to check the result.
5050 pp = set_store_for_read(d.ps, &pi, d.id,
5051 d.do_interlace ? (d.ps->progressive ?
5052 "pngvalid progressive deinterlacer" :
5053 "pngvalid sequential deinterlacer") : (d.ps->progressive ?
5054 "progressive reader" : "sequential reader"));
5056 /* Initialize the palette correctly from the png_store_file. */
5057 standard_palette_init(&d);
5059 /* Introduce the correct read function. */
5060 if (d.ps->progressive)
5062 png_set_progressive_read_fn(pp, &d, standard_info, progressive_row,
5065 /* Now feed data into the reader until we reach the end: */
5066 store_progressive_read(d.ps, pp, pi);
5070 /* Note that this takes the store, not the display. */
5071 png_set_read_fn(pp, d.ps, store_read);
5073 /* Check the header values: */
5074 png_read_info(pp, pi);
5076 /* The code tests both versions of the images that the sequential
5077 * reader can produce.
5079 standard_info_imp(&d, pp, pi, 2 /*images*/);
5081 /* Need the total bytes in the image below; we can't get to this point
5082 * unless the PNG file values have been checked against the expected
5086 sequential_row(&d, pp, pi, 0, 1);
5088 /* After the last pass loop over the rows again to check that the
5093 standard_text_validate(&d, pp, pi, 1/*check_end*/);
5094 standard_image_validate(&d, pp, 0, 1);
5097 d.ps->validated = 1;
5101 /* Check for validation. */
5102 if (!d.ps->validated)
5103 png_error(pp, "image read failed silently");
5105 /* Successful completion. */
5109 d.ps = fault; /* make sure this hasn't been clobbered. */
5111 /* In either case clean up the store. */
5112 store_read_reset(d.ps);
5116 test_standard(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
5117 int bdlo, int PNG_CONST bdhi)
5119 for (; bdlo <= bdhi; ++bdlo)
5123 for (interlace_type = PNG_INTERLACE_NONE;
5124 interlace_type < INTERLACE_LAST; ++interlace_type)
5126 standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
5127 interlace_type, 0, 0, 0), 0/*do_interlace*/, pm->use_update_info);
5134 return 1; /* keep going */
5138 perform_standard_test(png_modifier *pm)
5140 /* Test each colour type over the valid range of bit depths (expressed as
5141 * log2(bit_depth) in turn, stop as soon as any error is detected.
5143 if (!test_standard(pm, 0, 0, READ_BDHI))
5146 if (!test_standard(pm, 2, 3, READ_BDHI))
5149 if (!test_standard(pm, 3, 0, 3))
5152 if (!test_standard(pm, 4, 3, READ_BDHI))
5155 if (!test_standard(pm, 6, 3, READ_BDHI))
5160 /********************************** SIZE TESTS ********************************/
5162 test_size(png_modifier* PNG_CONST pm, png_byte PNG_CONST colour_type,
5163 int bdlo, int PNG_CONST bdhi)
5165 /* Run the tests on each combination.
5167 * NOTE: on my 32 bit x86 each of the following blocks takes
5168 * a total of 3.5 seconds if done across every combo of bit depth
5169 * width and height. This is a waste of time in practice, hence the
5170 * hinc and winc stuff:
5172 static PNG_CONST png_byte hinc[] = {1, 3, 11, 1, 5};
5173 static PNG_CONST png_byte winc[] = {1, 9, 5, 7, 1};
5174 for (; bdlo <= bdhi; ++bdlo)
5178 for (h=1; h<=16; h+=hinc[bdlo]) for (w=1; w<=16; w+=winc[bdlo])
5180 /* First test all the 'size' images against the sequential
5181 * reader using libpng to deinterlace (where required.) This
5182 * validates the write side of libpng. There are four possibilities
5185 standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
5186 PNG_INTERLACE_NONE, w, h, 0), 0/*do_interlace*/,
5187 pm->use_update_info);
5192 standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
5193 PNG_INTERLACE_NONE, w, h, 1), 0/*do_interlace*/,
5194 pm->use_update_info);
5199 # ifdef PNG_WRITE_INTERLACING_SUPPORTED
5200 standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
5201 PNG_INTERLACE_ADAM7, w, h, 0), 0/*do_interlace*/,
5202 pm->use_update_info);
5207 standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
5208 PNG_INTERLACE_ADAM7, w, h, 1), 0/*do_interlace*/,
5209 pm->use_update_info);
5215 /* Now validate the interlaced read side - do_interlace true,
5216 * in the progressive case this does actually make a difference
5217 * to the code used in the non-interlaced case too.
5219 standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
5220 PNG_INTERLACE_NONE, w, h, 0), 1/*do_interlace*/,
5221 pm->use_update_info);
5226 # ifdef PNG_WRITE_INTERLACING_SUPPORTED
5227 standard_test(&pm->this, FILEID(colour_type, DEPTH(bdlo), 0/*palette*/,
5228 PNG_INTERLACE_ADAM7, w, h, 0), 1/*do_interlace*/,
5229 pm->use_update_info);
5237 return 1; /* keep going */
5241 perform_size_test(png_modifier *pm)
5243 /* Test each colour type over the valid range of bit depths (expressed as
5244 * log2(bit_depth) in turn, stop as soon as any error is detected.
5246 if (!test_size(pm, 0, 0, READ_BDHI))
5249 if (!test_size(pm, 2, 3, READ_BDHI))
5252 /* For the moment don't do the palette test - it's a waste of time when
5253 * compared to the grayscale test.
5256 if (!test_size(pm, 3, 0, 3))
5260 if (!test_size(pm, 4, 3, READ_BDHI))
5263 if (!test_size(pm, 6, 3, READ_BDHI))
5268 /******************************* TRANSFORM TESTS ******************************/
5269 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
5270 /* A set of tests to validate libpng image transforms. The possibilities here
5271 * are legion because the transforms can be combined in a combinatorial
5272 * fashion. To deal with this some measure of restraint is required, otherwise
5273 * the tests would take forever.
5275 typedef struct image_pixel
5277 /* A local (pngvalid) representation of a PNG pixel, in all its
5280 unsigned int red, green, blue, alpha; /* For non-palette images. */
5281 unsigned int palette_index; /* For a palette image. */
5282 png_byte colour_type; /* As in the spec. */
5283 png_byte bit_depth; /* Defines bit size in row */
5284 png_byte sample_depth; /* Scale of samples */
5285 int have_tRNS; /* tRNS chunk may need processing */
5287 /* For checking the code calculates double precision floating point values
5288 * along with an error value, accumulated from the transforms. Because an
5289 * sBIT setting allows larger error bounds (indeed, by the spec, apparently
5290 * up to just less than +/-1 in the scaled value) the *lowest* sBIT for each
5291 * channel is stored. This sBIT value is folded in to the stored error value
5292 * at the end of the application of the transforms to the pixel.
5294 double redf, greenf, bluef, alphaf;
5295 double rede, greene, bluee, alphae;
5296 png_byte red_sBIT, green_sBIT, blue_sBIT, alpha_sBIT;
5299 /* Shared utility function, see below. */
5301 image_pixel_setf(image_pixel *this, unsigned int max)
5303 this->redf = this->red / (double)max;
5304 this->greenf = this->green / (double)max;
5305 this->bluef = this->blue / (double)max;
5306 this->alphaf = this->alpha / (double)max;
5308 if (this->red < max)
5309 this->rede = this->redf * DBL_EPSILON;
5312 if (this->green < max)
5313 this->greene = this->greenf * DBL_EPSILON;
5316 if (this->blue < max)
5317 this->bluee = this->bluef * DBL_EPSILON;
5320 if (this->alpha < max)
5321 this->alphae = this->alphaf * DBL_EPSILON;
5326 /* Initialize the structure for the next pixel - call this before doing any
5327 * transforms and call it for each pixel since all the fields may need to be
5331 image_pixel_init(image_pixel *this, png_const_bytep row, png_byte colour_type,
5332 png_byte bit_depth, png_uint_32 x, store_palette palette)
5334 PNG_CONST png_byte sample_depth = (png_byte)(colour_type ==
5335 PNG_COLOR_TYPE_PALETTE ? 8 : bit_depth);
5336 PNG_CONST unsigned int max = (1U<<sample_depth)-1;
5338 /* Initially just set everything to the same number and the alpha to opaque.
5339 * Note that this currently assumes a simple palette where entry x has colour
5342 this->palette_index = this->red = this->green = this->blue =
5343 sample(row, colour_type, bit_depth, x, 0);
5345 this->red_sBIT = this->green_sBIT = this->blue_sBIT = this->alpha_sBIT =
5348 /* Then override as appropriate: */
5349 if (colour_type == 3) /* palette */
5351 /* This permits the caller to default to the sample value. */
5354 PNG_CONST unsigned int i = this->palette_index;
5356 this->red = palette[i].red;
5357 this->green = palette[i].green;
5358 this->blue = palette[i].blue;
5359 this->alpha = palette[i].alpha;
5363 else /* not palette */
5367 if (colour_type & 2)
5369 this->green = sample(row, colour_type, bit_depth, x, 1);
5370 this->blue = sample(row, colour_type, bit_depth, x, 2);
5373 if (colour_type & 4)
5374 this->alpha = sample(row, colour_type, bit_depth, x, ++i);
5377 /* Calculate the scaled values, these are simply the values divided by
5378 * 'max' and the error is initialized to the double precision epsilon value
5379 * from the header file.
5381 image_pixel_setf(this, max);
5383 /* Store the input information for use in the transforms - these will
5384 * modify the information.
5386 this->colour_type = colour_type;
5387 this->bit_depth = bit_depth;
5388 this->sample_depth = sample_depth;
5389 this->have_tRNS = 0;
5392 /* Convert a palette image to an rgb image. This necessarily converts the tRNS
5393 * chunk at the same time, because the tRNS will be in palette form. The way
5394 * palette validation works means that the original palette is never updated,
5395 * instead the image_pixel value from the row contains the RGB of the
5396 * corresponding palette entry and *this* is updated. Consequently this routine
5397 * only needs to change the colour type information.
5400 image_pixel_convert_PLTE(image_pixel *this)
5402 if (this->colour_type == PNG_COLOR_TYPE_PALETTE)
5404 if (this->have_tRNS)
5406 this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
5407 this->have_tRNS = 0;
5410 this->colour_type = PNG_COLOR_TYPE_RGB;
5412 /* The bit depth of the row changes at this point too (notice that this is
5413 * the row format, not the sample depth, which is separate.)
5415 this->bit_depth = 8;
5419 /* Add an alpha channel; this will import the tRNS information because tRNS is
5420 * not valid in an alpha image. The bit depth will invariably be set to at
5421 * least 8. Palette images will be converted to alpha (using the above API).
5424 image_pixel_add_alpha(image_pixel *this, PNG_CONST standard_display *display)
5426 if (this->colour_type == PNG_COLOR_TYPE_PALETTE)
5427 image_pixel_convert_PLTE(this);
5429 if ((this->colour_type & PNG_COLOR_MASK_ALPHA) == 0)
5431 if (this->colour_type == PNG_COLOR_TYPE_GRAY)
5433 if (this->bit_depth < 8)
5434 this->bit_depth = 8;
5436 if (this->have_tRNS)
5438 this->have_tRNS = 0;
5440 /* Check the input, original, channel value here against the
5441 * original tRNS gray chunk valie.
5443 if (this->red == display->transparent.red)
5451 this->colour_type = PNG_COLOR_TYPE_GRAY_ALPHA;
5454 else if (this->colour_type == PNG_COLOR_TYPE_RGB)
5456 if (this->have_tRNS)
5458 this->have_tRNS = 0;
5460 /* Again, check the exact input values, not the current transformed
5463 if (this->red == display->transparent.red &&
5464 this->green == display->transparent.green &&
5465 this->blue == display->transparent.blue)
5470 this->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
5474 /* The error in the alpha is zero and the sBIT value comes from the
5475 * original sBIT data (actually it will always be the original bit depth).
5478 this->alpha_sBIT = display->alpha_sBIT;
5482 struct transform_display;
5483 typedef struct image_transform
5485 /* The name of this transform: a string. */
5486 PNG_CONST char *name;
5488 /* Each transform can be disabled from the command line: */
5491 /* The global list of transforms; read only. */
5492 struct image_transform *PNG_CONST list;
5494 /* The global count of the number of times this transform has been set on an
5497 unsigned int global_use;
5499 /* The local count of the number of times this transform has been set. */
5500 unsigned int local_use;
5502 /* The next transform in the list, each transform must call its own next
5503 * transform after it has processed the pixel successfully.
5505 PNG_CONST struct image_transform *next;
5507 /* A single transform for the image, expressed as a series of function
5508 * callbacks and some space for values.
5510 * First a callback to add any required modifications to the png_modifier;
5511 * this gets called just before the modifier is set up for read.
5513 void (*ini)(PNG_CONST struct image_transform *this,
5514 struct transform_display *that);
5516 /* And a callback to set the transform on the current png_read_struct:
5518 void (*set)(PNG_CONST struct image_transform *this,
5519 struct transform_display *that, png_structp pp, png_infop pi);
5521 /* Then a transform that takes an input pixel in one PNG format or another
5522 * and modifies it by a pngvalid implementation of the transform (thus
5523 * duplicating the libpng intent without, we hope, duplicating the bugs
5524 * in the libpng implementation!) The png_structp is solely to allow error
5525 * reporting via png_error and png_warning.
5527 void (*mod)(PNG_CONST struct image_transform *this, image_pixel *that,
5528 png_const_structp pp, PNG_CONST struct transform_display *display);
5530 /* Add this transform to the list and return true if the transform is
5531 * meaningful for this colour type and bit depth - if false then the
5532 * transform should have no effect on the image so there's not a lot of
5535 int (*add)(struct image_transform *this,
5536 PNG_CONST struct image_transform **that, png_byte colour_type,
5537 png_byte bit_depth);
5540 typedef struct transform_display
5542 standard_display this;
5546 PNG_CONST image_transform* transform_list;
5548 /* Local variables */
5549 png_byte output_colour_type;
5550 png_byte output_bit_depth;
5552 /* Modifications (not necessarily used.) */
5553 gama_modification gama_mod;
5554 chrm_modification chrm_mod;
5555 srgb_modification srgb_mod;
5556 } transform_display;
5558 /* Set sRGB, cHRM and gAMA transforms as required by the current encoding. */
5560 transform_set_encoding(transform_display *this)
5562 /* Set up the png_modifier '_current' fields then use these to determine how
5563 * to add appropriate chunks.
5565 png_modifier *pm = this->pm;
5567 modifier_set_encoding(pm);
5569 if (modifier_color_encoding_is_set(pm))
5571 if (modifier_color_encoding_is_sRGB(pm))
5572 srgb_modification_init(&this->srgb_mod, pm, PNG_sRGB_INTENT_ABSOLUTE);
5576 /* Set gAMA and cHRM separately. */
5577 gama_modification_init(&this->gama_mod, pm, pm->current_gamma);
5579 if (pm->current_encoding != 0)
5580 chrm_modification_init(&this->chrm_mod, pm, pm->current_encoding);
5585 /* Three functions to end the list: */
5587 image_transform_ini_end(PNG_CONST image_transform *this,
5588 transform_display *that)
5595 image_transform_set_end(PNG_CONST image_transform *this,
5596 transform_display *that, png_structp pp, png_infop pi)
5604 /* At the end of the list recalculate the output image pixel value from the
5605 * double precision values set up by the preceding 'mod' calls:
5608 sample_scale(double sample_value, unsigned int scale)
5610 sample_value = floor(sample_value * scale + .5);
5612 /* Return NaN as 0: */
5613 if (!(sample_value > 0))
5615 else if (sample_value > scale)
5616 sample_value = scale;
5618 return (unsigned int)sample_value;
5622 image_transform_mod_end(PNG_CONST image_transform *this, image_pixel *that,
5623 png_const_structp pp, PNG_CONST transform_display *display)
5625 PNG_CONST unsigned int scale = (1U<<that->sample_depth)-1;
5631 /* At the end recalculate the digitized red green and blue values according
5632 * to the current sample_depth of the pixel.
5634 * The sample value is simply scaled to the maximum, checking for over
5635 * and underflow (which can both happen for some image transforms,
5636 * including simple size scaling, though libpng doesn't do that at present.
5638 that->red = sample_scale(that->redf, scale);
5640 /* The error value is increased, at the end, according to the lowest sBIT
5641 * value seen. Common sense tells us that the intermediate integer
5642 * representations are no more accurate than +/- 0.5 in the integral values,
5643 * the sBIT allows the implementation to be worse than this. In addition the
5644 * PNG specification actually permits any error within the range (-1..+1),
5645 * but that is ignored here. Instead the final digitized value is compared,
5646 * below to the digitized value of the error limits - this has the net effect
5647 * of allowing (almost) +/-1 in the output value. It's difficult to see how
5648 * any algorithm that digitizes intermediate results can be more accurate.
5650 that->rede += 1./(2*((1U<<that->red_sBIT)-1));
5652 if (that->colour_type & PNG_COLOR_MASK_COLOR)
5654 that->green = sample_scale(that->greenf, scale);
5655 that->blue = sample_scale(that->bluef, scale);
5656 that->greene += 1./(2*((1U<<that->green_sBIT)-1));
5657 that->bluee += 1./(2*((1U<<that->blue_sBIT)-1));
5661 that->blue = that->green = that->red;
5662 that->bluef = that->greenf = that->redf;
5663 that->bluee = that->greene = that->rede;
5666 if ((that->colour_type & PNG_COLOR_MASK_ALPHA) ||
5667 that->colour_type == PNG_COLOR_TYPE_PALETTE)
5669 that->alpha = sample_scale(that->alphaf, scale);
5670 that->alphae += 1./(2*((1U<<that->alpha_sBIT)-1));
5674 that->alpha = scale; /* opaque */
5675 that->alpha = 1; /* Override this. */
5676 that->alphae = 0; /* It's exact ;-) */
5680 /* Static 'end' structure: */
5681 static image_transform image_transform_end =
5689 image_transform_ini_end,
5690 image_transform_set_end,
5691 image_transform_mod_end,
5692 0 /* never called, I want it to crash if it is! */
5695 /* Reader callbacks and implementations, where they differ from the standard
5699 transform_display_init(transform_display *dp, png_modifier *pm, png_uint_32 id,
5700 PNG_CONST image_transform *transform_list)
5702 memset(dp, 0, sizeof *dp);
5704 /* Standard fields */
5705 standard_display_init(&dp->this, &pm->this, id, 0/*do_interlace*/,
5706 pm->use_update_info);
5708 /* Parameter fields */
5710 dp->transform_list = transform_list;
5712 /* Local variable fields */
5713 dp->output_colour_type = 255; /* invalid */
5714 dp->output_bit_depth = 255; /* invalid */
5718 transform_info_imp(transform_display *dp, png_structp pp, png_infop pi)
5720 /* Reuse the standard stuff as appropriate. */
5721 standard_info_part1(&dp->this, pp, pi);
5723 /* Now set the list of transforms. */
5724 dp->transform_list->set(dp->transform_list, dp, pp, pi);
5726 /* Update the info structure for these transforms: */
5728 int i = dp->this.use_update_info;
5729 /* Always do one call, even if use_update_info is 0. */
5731 png_read_update_info(pp, pi);
5735 /* And get the output information into the standard_display */
5736 standard_info_part2(&dp->this, pp, pi, 1/*images*/);
5738 /* Plus the extra stuff we need for the transform tests: */
5739 dp->output_colour_type = png_get_color_type(pp, pi);
5740 dp->output_bit_depth = png_get_bit_depth(pp, pi);
5742 /* Validate the combination of colour type and bit depth that we are getting
5743 * out of libpng; the semantics of something not in the PNG spec are, at
5746 switch (dp->output_colour_type)
5748 case PNG_COLOR_TYPE_PALETTE:
5749 if (dp->output_bit_depth > 8) goto error;
5751 case PNG_COLOR_TYPE_GRAY:
5752 if (dp->output_bit_depth == 1 || dp->output_bit_depth == 2 ||
5753 dp->output_bit_depth == 4)
5757 if (dp->output_bit_depth == 8 || dp->output_bit_depth == 16)
5765 pos = safecat(message, sizeof message, 0,
5766 "invalid final bit depth: colour type(");
5767 pos = safecatn(message, sizeof message, pos, dp->output_colour_type);
5768 pos = safecat(message, sizeof message, pos, ") with bit depth: ");
5769 pos = safecatn(message, sizeof message, pos, dp->output_bit_depth);
5771 png_error(pp, message);
5775 /* Use a test pixel to check that the output agrees with what we expect -
5776 * this avoids running the whole test if the output is unexpected.
5779 image_pixel test_pixel;
5781 memset(&test_pixel, 0, sizeof test_pixel);
5782 test_pixel.colour_type = dp->this.colour_type; /* input */
5783 test_pixel.bit_depth = dp->this.bit_depth;
5784 if (test_pixel.colour_type == PNG_COLOR_TYPE_PALETTE)
5785 test_pixel.sample_depth = 8;
5787 test_pixel.sample_depth = test_pixel.bit_depth;
5788 /* Don't need sBIT here, but it must be set to non-zero to avoid
5789 * arithmetic overflows.
5791 test_pixel.have_tRNS = dp->this.is_transparent;
5792 test_pixel.red_sBIT = test_pixel.green_sBIT = test_pixel.blue_sBIT =
5793 test_pixel.alpha_sBIT = test_pixel.sample_depth;
5795 dp->transform_list->mod(dp->transform_list, &test_pixel, pp, dp);
5797 if (test_pixel.colour_type != dp->output_colour_type)
5800 size_t pos = safecat(message, sizeof message, 0, "colour type ");
5802 pos = safecatn(message, sizeof message, pos, dp->output_colour_type);
5803 pos = safecat(message, sizeof message, pos, " expected ");
5804 pos = safecatn(message, sizeof message, pos, test_pixel.colour_type);
5806 png_error(pp, message);
5809 if (test_pixel.bit_depth != dp->output_bit_depth)
5812 size_t pos = safecat(message, sizeof message, 0, "bit depth ");
5814 pos = safecatn(message, sizeof message, pos, dp->output_bit_depth);
5815 pos = safecat(message, sizeof message, pos, " expected ");
5816 pos = safecatn(message, sizeof message, pos, test_pixel.bit_depth);
5818 png_error(pp, message);
5821 /* If both bit depth and colour type are correct check the sample depth.
5822 * I believe these are both internal errors.
5824 if (test_pixel.colour_type == PNG_COLOR_TYPE_PALETTE)
5826 if (test_pixel.sample_depth != 8) /* oops - internal error! */
5827 png_error(pp, "pngvalid: internal: palette sample depth not 8");
5829 else if (test_pixel.sample_depth != dp->output_bit_depth)
5832 size_t pos = safecat(message, sizeof message, 0,
5833 "internal: sample depth ");
5835 pos = safecatn(message, sizeof message, pos, dp->output_bit_depth);
5836 pos = safecat(message, sizeof message, pos, " expected ");
5837 pos = safecatn(message, sizeof message, pos, test_pixel.sample_depth);
5839 png_error(pp, message);
5844 static void PNGCBAPI
5845 transform_info(png_structp pp, png_infop pi)
5847 transform_info_imp(voidcast(transform_display*, png_get_progressive_ptr(pp)),
5852 transform_range_check(png_const_structp pp, unsigned int r, unsigned int g,
5853 unsigned int b, unsigned int a, unsigned int in_digitized, double in,
5854 unsigned int out, png_byte sample_depth, double err, double limit,
5855 PNG_CONST char *name, double digitization_error)
5857 /* Compare the scaled, digitzed, values of our local calculation (in+-err)
5858 * with the digitized values libpng produced; 'sample_depth' is the actual
5859 * digitization depth of the libpng output colors (the bit depth except for
5860 * palette images where it is always 8.) The check on 'err' is to detect
5861 * internal errors in pngvalid itself.
5863 unsigned int max = (1U<<sample_depth)-1;
5864 double in_min = ceil((in-err)*max - digitization_error);
5865 double in_max = floor((in+err)*max + digitization_error);
5866 if (err > limit || !(out >= in_min && out <= in_max))
5871 pos = safecat(message, sizeof message, 0, name);
5872 pos = safecat(message, sizeof message, pos, " output value error: rgba(");
5873 pos = safecatn(message, sizeof message, pos, r);
5874 pos = safecat(message, sizeof message, pos, ",");
5875 pos = safecatn(message, sizeof message, pos, g);
5876 pos = safecat(message, sizeof message, pos, ",");
5877 pos = safecatn(message, sizeof message, pos, b);
5878 pos = safecat(message, sizeof message, pos, ",");
5879 pos = safecatn(message, sizeof message, pos, a);
5880 pos = safecat(message, sizeof message, pos, "): ");
5881 pos = safecatn(message, sizeof message, pos, out);
5882 pos = safecat(message, sizeof message, pos, " expected: ");
5883 pos = safecatn(message, sizeof message, pos, in_digitized);
5884 pos = safecat(message, sizeof message, pos, " (");
5885 pos = safecatd(message, sizeof message, pos, (in-err)*max, 3);
5886 pos = safecat(message, sizeof message, pos, "..");
5887 pos = safecatd(message, sizeof message, pos, (in+err)*max, 3);
5888 pos = safecat(message, sizeof message, pos, ")");
5890 png_error(pp, message);
5895 transform_image_validate(transform_display *dp, png_const_structp pp,
5898 /* Constants for the loop below: */
5899 PNG_CONST png_store* PNG_CONST ps = dp->this.ps;
5900 PNG_CONST png_byte in_ct = dp->this.colour_type;
5901 PNG_CONST png_byte in_bd = dp->this.bit_depth;
5902 PNG_CONST png_uint_32 w = dp->this.w;
5903 PNG_CONST png_uint_32 h = dp->this.h;
5904 PNG_CONST png_byte out_ct = dp->output_colour_type;
5905 PNG_CONST png_byte out_bd = dp->output_bit_depth;
5906 PNG_CONST png_byte sample_depth = (png_byte)(out_ct ==
5907 PNG_COLOR_TYPE_PALETTE ? 8 : out_bd);
5908 PNG_CONST png_byte red_sBIT = dp->this.red_sBIT;
5909 PNG_CONST png_byte green_sBIT = dp->this.green_sBIT;
5910 PNG_CONST png_byte blue_sBIT = dp->this.blue_sBIT;
5911 PNG_CONST png_byte alpha_sBIT = dp->this.alpha_sBIT;
5912 PNG_CONST int have_tRNS = dp->this.is_transparent;
5913 double digitization_error;
5915 store_palette out_palette;
5920 /* Check for row overwrite errors */
5921 store_image_check(dp->this.ps, pp, 0);
5923 /* Read the palette corresponding to the output if the output colour type
5924 * indicates a palette, othewise set out_palette to garbage.
5926 if (out_ct == PNG_COLOR_TYPE_PALETTE)
5928 /* Validate that the palette count itself has not changed - this is not
5931 int npalette = (-1);
5933 (void)read_palette(out_palette, &npalette, pp, pi);
5934 if (npalette != dp->this.npalette)
5935 png_error(pp, "unexpected change in palette size");
5937 digitization_error = .5;
5941 png_byte in_sample_depth;
5943 memset(out_palette, 0x5e, sizeof out_palette);
5945 /* use-input-precision means assume that if the input has 8 bit (or less)
5946 * samples and the output has 16 bit samples the calculations will be done
5947 * with 8 bit precision, not 16.
5949 if (in_ct == PNG_COLOR_TYPE_PALETTE || in_bd < 16)
5950 in_sample_depth = 8;
5952 in_sample_depth = in_bd;
5954 if (sample_depth != 16 || in_sample_depth > 8 ||
5955 !dp->pm->calculations_use_input_precision)
5956 digitization_error = .5;
5958 /* Else calculations are at 8 bit precision, and the output actually
5959 * consists of scaled 8-bit values, so scale .5 in 8 bits to the 16 bits:
5962 digitization_error = .5 * 257;
5967 png_const_bytep PNG_CONST pRow = store_image_row(ps, pp, 0, y);
5970 /* The original, standard, row pre-transforms. */
5971 png_byte std[STANDARD_ROWMAX];
5973 transform_row(pp, std, in_ct, in_bd, y);
5975 /* Go through each original pixel transforming it and comparing with what
5976 * libpng did to the same pixel.
5980 image_pixel in_pixel, out_pixel;
5981 unsigned int r, g, b, a;
5983 /* Find out what we think the pixel should be: */
5984 image_pixel_init(&in_pixel, std, in_ct, in_bd, x, dp->this.palette);
5986 in_pixel.red_sBIT = red_sBIT;
5987 in_pixel.green_sBIT = green_sBIT;
5988 in_pixel.blue_sBIT = blue_sBIT;
5989 in_pixel.alpha_sBIT = alpha_sBIT;
5990 in_pixel.have_tRNS = have_tRNS;
5992 /* For error detection, below. */
5998 dp->transform_list->mod(dp->transform_list, &in_pixel, pp, dp);
6000 /* Read the output pixel and compare it to what we got, we don't
6001 * use the error field here, so no need to update sBIT.
6003 image_pixel_init(&out_pixel, pRow, out_ct, out_bd, x, out_palette);
6005 /* We don't expect changes to the index here even if the bit depth is
6008 if (in_ct == PNG_COLOR_TYPE_PALETTE &&
6009 out_ct == PNG_COLOR_TYPE_PALETTE)
6011 if (in_pixel.palette_index != out_pixel.palette_index)
6012 png_error(pp, "unexpected transformed palette index");
6015 /* Check the colours for palette images too - in fact the palette could
6016 * be separately verified itself in most cases.
6018 if (in_pixel.red != out_pixel.red)
6019 transform_range_check(pp, r, g, b, a, in_pixel.red, in_pixel.redf,
6020 out_pixel.red, sample_depth, in_pixel.rede,
6021 dp->pm->limit + 1./(2*((1U<<in_pixel.red_sBIT)-1)), "red/gray",
6022 digitization_error);
6024 if ((out_ct & PNG_COLOR_MASK_COLOR) != 0 &&
6025 in_pixel.green != out_pixel.green)
6026 transform_range_check(pp, r, g, b, a, in_pixel.green,
6027 in_pixel.greenf, out_pixel.green, sample_depth, in_pixel.greene,
6028 dp->pm->limit + 1./(2*((1U<<in_pixel.green_sBIT)-1)), "green",
6029 digitization_error);
6031 if ((out_ct & PNG_COLOR_MASK_COLOR) != 0 &&
6032 in_pixel.blue != out_pixel.blue)
6033 transform_range_check(pp, r, g, b, a, in_pixel.blue, in_pixel.bluef,
6034 out_pixel.blue, sample_depth, in_pixel.bluee,
6035 dp->pm->limit + 1./(2*((1U<<in_pixel.blue_sBIT)-1)), "blue",
6036 digitization_error);
6038 if ((out_ct & PNG_COLOR_MASK_ALPHA) != 0 &&
6039 in_pixel.alpha != out_pixel.alpha)
6040 transform_range_check(pp, r, g, b, a, in_pixel.alpha,
6041 in_pixel.alphaf, out_pixel.alpha, sample_depth, in_pixel.alphae,
6042 dp->pm->limit + 1./(2*((1U<<in_pixel.alpha_sBIT)-1)), "alpha",
6043 digitization_error);
6044 } /* pixel (x) loop */
6045 } /* row (y) loop */
6047 /* Record that something was actually checked to avoid a false positive. */
6048 dp->this.ps->validated = 1;
6051 static void PNGCBAPI
6052 transform_end(png_structp ppIn, png_infop pi)
6054 png_const_structp pp = ppIn;
6055 transform_display *dp = voidcast(transform_display*,
6056 png_get_progressive_ptr(pp));
6058 if (!dp->this.speed)
6059 transform_image_validate(dp, pp, pi);
6061 dp->this.ps->validated = 1;
6064 /* A single test run. */
6066 transform_test(png_modifier *pmIn, PNG_CONST png_uint_32 idIn,
6067 PNG_CONST image_transform* transform_listIn, PNG_CONST char * volatile name)
6069 transform_display d;
6070 context(&pmIn->this, fault);
6072 transform_display_init(&d, pmIn, idIn, transform_listIn);
6079 char full_name[256];
6081 /* Make sure the encoding fields are correct and enter the required
6084 transform_set_encoding(&d);
6086 /* Add any modifications required by the transform list. */
6087 d.transform_list->ini(d.transform_list, &d);
6089 /* Add the color space information, if any, to the name. */
6090 pos = safecat(full_name, sizeof full_name, pos, name);
6091 pos = safecat_current_encoding(full_name, sizeof full_name, pos, d.pm);
6093 /* Get a png_struct for reading the image. */
6094 pp = set_modifier_for_read(d.pm, &pi, d.this.id, full_name);
6095 standard_palette_init(&d.this);
6098 /* Logging (debugging only) */
6102 (void)store_message(&d.pm->this, pp, buffer, sizeof buffer, 0,
6105 fprintf(stderr, "%s\n", buffer);
6109 /* Introduce the correct read function. */
6110 if (d.pm->this.progressive)
6112 /* Share the row function with the standard implementation. */
6113 png_set_progressive_read_fn(pp, &d, transform_info, progressive_row,
6116 /* Now feed data into the reader until we reach the end: */
6117 modifier_progressive_read(d.pm, pp, pi);
6121 /* modifier_read expects a png_modifier* */
6122 png_set_read_fn(pp, d.pm, modifier_read);
6124 /* Check the header values: */
6125 png_read_info(pp, pi);
6127 /* Process the 'info' requirements. Only one image is generated */
6128 transform_info_imp(&d, pp, pi);
6130 sequential_row(&d.this, pp, pi, -1, 0);
6133 transform_image_validate(&d, pp, pi);
6135 d.this.ps->validated = 1;
6138 modifier_reset(d.pm);
6143 modifier_reset(voidcast(png_modifier*,(void*)fault));
6147 /* The transforms: */
6148 #define ITSTRUCT(name) image_transform_##name
6149 #define ITDATA(name) image_transform_data_##name
6150 #define image_transform_ini image_transform_default_ini
6152 static image_transform ITSTRUCT(name) =\
6160 image_transform_ini,\
6161 image_transform_png_set_##name##_set,\
6162 image_transform_png_set_##name##_mod,\
6163 image_transform_png_set_##name##_add\
6165 #define PT ITSTRUCT(end) /* stores the previous transform */
6169 image_transform_default_ini(PNG_CONST image_transform *this,
6170 transform_display *that)
6172 this->next->ini(this->next, that);
6175 #ifdef PNG_READ_BACKGROUND_SUPPORTED
6177 image_transform_default_add(image_transform *this,
6178 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
6190 #ifdef PNG_READ_EXPAND_SUPPORTED
6191 /* png_set_palette_to_rgb */
6193 image_transform_png_set_palette_to_rgb_set(PNG_CONST image_transform *this,
6194 transform_display *that, png_structp pp, png_infop pi)
6196 png_set_palette_to_rgb(pp);
6197 this->next->set(this->next, that, pp, pi);
6201 image_transform_png_set_palette_to_rgb_mod(PNG_CONST image_transform *this,
6202 image_pixel *that, png_const_structp pp,
6203 PNG_CONST transform_display *display)
6205 if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
6206 image_pixel_convert_PLTE(that);
6208 this->next->mod(this->next, that, pp, display);
6212 image_transform_png_set_palette_to_rgb_add(image_transform *this,
6213 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
6220 return colour_type == PNG_COLOR_TYPE_PALETTE;
6225 #define PT ITSTRUCT(palette_to_rgb)
6226 #endif /* PNG_READ_EXPAND_SUPPORTED */
6228 #ifdef PNG_READ_EXPAND_SUPPORTED
6229 /* png_set_tRNS_to_alpha */
6231 image_transform_png_set_tRNS_to_alpha_set(PNG_CONST image_transform *this,
6232 transform_display *that, png_structp pp, png_infop pi)
6234 png_set_tRNS_to_alpha(pp);
6235 this->next->set(this->next, that, pp, pi);
6239 image_transform_png_set_tRNS_to_alpha_mod(PNG_CONST image_transform *this,
6240 image_pixel *that, png_const_structp pp,
6241 PNG_CONST transform_display *display)
6243 /* LIBPNG BUG: this always forces palette images to RGB. */
6244 if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
6245 image_pixel_convert_PLTE(that);
6247 /* This effectively does an 'expand' only if there is some transparency to
6248 * convert to an alpha channel.
6250 if (that->have_tRNS)
6251 image_pixel_add_alpha(that, &display->this);
6253 /* LIBPNG BUG: otherwise libpng still expands to 8 bits! */
6256 if (that->bit_depth < 8)
6258 if (that->sample_depth < 8)
6259 that->sample_depth = 8;
6262 this->next->mod(this->next, that, pp, display);
6266 image_transform_png_set_tRNS_to_alpha_add(image_transform *this,
6267 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
6274 /* We don't know yet whether there will be a tRNS chunk, but we know that
6275 * this transformation should do nothing if there already is an alpha
6278 return (colour_type & PNG_COLOR_MASK_ALPHA) == 0;
6283 #define PT ITSTRUCT(tRNS_to_alpha)
6284 #endif /* PNG_READ_EXPAND_SUPPORTED */
6286 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
6287 /* png_set_gray_to_rgb */
6289 image_transform_png_set_gray_to_rgb_set(PNG_CONST image_transform *this,
6290 transform_display *that, png_structp pp, png_infop pi)
6292 png_set_gray_to_rgb(pp);
6293 this->next->set(this->next, that, pp, pi);
6297 image_transform_png_set_gray_to_rgb_mod(PNG_CONST image_transform *this,
6298 image_pixel *that, png_const_structp pp,
6299 PNG_CONST transform_display *display)
6301 /* NOTE: we can actually pend the tRNS processing at this point because we
6302 * can correctly recognize the original pixel value even though we have
6303 * mapped the one gray channel to the three RGB ones, but in fact libpng
6304 * doesn't do this, so we don't either.
6306 if ((that->colour_type & PNG_COLOR_MASK_COLOR) == 0 && that->have_tRNS)
6307 image_pixel_add_alpha(that, &display->this);
6309 /* Simply expand the bit depth and alter the colour type as required. */
6310 if (that->colour_type == PNG_COLOR_TYPE_GRAY)
6312 /* RGB images have a bit depth at least equal to '8' */
6313 if (that->bit_depth < 8)
6314 that->sample_depth = that->bit_depth = 8;
6316 /* And just changing the colour type works here because the green and blue
6317 * channels are being maintained in lock-step with the red/gray:
6319 that->colour_type = PNG_COLOR_TYPE_RGB;
6322 else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
6323 that->colour_type = PNG_COLOR_TYPE_RGB_ALPHA;
6325 this->next->mod(this->next, that, pp, display);
6329 image_transform_png_set_gray_to_rgb_add(image_transform *this,
6330 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
6337 return (colour_type & PNG_COLOR_MASK_COLOR) == 0;
6342 #define PT ITSTRUCT(gray_to_rgb)
6343 #endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED */
6345 #ifdef PNG_READ_EXPAND_SUPPORTED
6346 /* png_set_expand */
6348 image_transform_png_set_expand_set(PNG_CONST image_transform *this,
6349 transform_display *that, png_structp pp, png_infop pi)
6352 this->next->set(this->next, that, pp, pi);
6356 image_transform_png_set_expand_mod(PNG_CONST image_transform *this,
6357 image_pixel *that, png_const_structp pp,
6358 PNG_CONST transform_display *display)
6360 /* The general expand case depends on what the colour type is: */
6361 if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
6362 image_pixel_convert_PLTE(that);
6363 else if (that->bit_depth < 8) /* grayscale */
6364 that->sample_depth = that->bit_depth = 8;
6366 if (that->have_tRNS)
6367 image_pixel_add_alpha(that, &display->this);
6369 this->next->mod(this->next, that, pp, display);
6373 image_transform_png_set_expand_add(image_transform *this,
6374 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
6381 /* 'expand' should do nothing for RGBA or GA input - no tRNS and the bit
6382 * depth is at least 8 already.
6384 return (colour_type & PNG_COLOR_MASK_ALPHA) == 0;
6389 #define PT ITSTRUCT(expand)
6390 #endif /* PNG_READ_EXPAND_SUPPORTED */
6392 #ifdef PNG_READ_EXPAND_SUPPORTED
6393 /* png_set_expand_gray_1_2_4_to_8
6394 * LIBPNG BUG: this just does an 'expand'
6397 image_transform_png_set_expand_gray_1_2_4_to_8_set(
6398 PNG_CONST image_transform *this, transform_display *that, png_structp pp,
6401 png_set_expand_gray_1_2_4_to_8(pp);
6402 this->next->set(this->next, that, pp, pi);
6406 image_transform_png_set_expand_gray_1_2_4_to_8_mod(
6407 PNG_CONST image_transform *this, image_pixel *that, png_const_structp pp,
6408 PNG_CONST transform_display *display)
6410 image_transform_png_set_expand_mod(this, that, pp, display);
6414 image_transform_png_set_expand_gray_1_2_4_to_8_add(image_transform *this,
6415 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
6417 return image_transform_png_set_expand_add(this, that, colour_type,
6421 IT(expand_gray_1_2_4_to_8);
6423 #define PT ITSTRUCT(expand_gray_1_2_4_to_8)
6424 #endif /* PNG_READ_EXPAND_SUPPORTED */
6426 #ifdef PNG_READ_EXPAND_16_SUPPORTED
6427 /* png_set_expand_16 */
6429 image_transform_png_set_expand_16_set(PNG_CONST image_transform *this,
6430 transform_display *that, png_structp pp, png_infop pi)
6432 png_set_expand_16(pp);
6433 this->next->set(this->next, that, pp, pi);
6437 image_transform_png_set_expand_16_mod(PNG_CONST image_transform *this,
6438 image_pixel *that, png_const_structp pp,
6439 PNG_CONST transform_display *display)
6441 /* Expect expand_16 to expand everything to 16 bits as a result of also
6442 * causing 'expand' to happen.
6444 if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
6445 image_pixel_convert_PLTE(that);
6447 if (that->have_tRNS)
6448 image_pixel_add_alpha(that, &display->this);
6450 if (that->bit_depth < 16)
6451 that->sample_depth = that->bit_depth = 16;
6453 this->next->mod(this->next, that, pp, display);
6457 image_transform_png_set_expand_16_add(image_transform *this,
6458 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
6465 /* expand_16 does something unless the bit depth is already 16. */
6466 return bit_depth < 16;
6471 #define PT ITSTRUCT(expand_16)
6472 #endif /* PNG_READ_EXPAND_16_SUPPORTED */
6474 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED /* API added in 1.5.4 */
6475 /* png_set_scale_16 */
6477 image_transform_png_set_scale_16_set(PNG_CONST image_transform *this,
6478 transform_display *that, png_structp pp, png_infop pi)
6480 png_set_scale_16(pp);
6481 this->next->set(this->next, that, pp, pi);
6485 image_transform_png_set_scale_16_mod(PNG_CONST image_transform *this,
6486 image_pixel *that, png_const_structp pp,
6487 PNG_CONST transform_display *display)
6489 if (that->bit_depth == 16)
6491 that->sample_depth = that->bit_depth = 8;
6492 if (that->red_sBIT > 8) that->red_sBIT = 8;
6493 if (that->green_sBIT > 8) that->green_sBIT = 8;
6494 if (that->blue_sBIT > 8) that->blue_sBIT = 8;
6495 if (that->alpha_sBIT > 8) that->alpha_sBIT = 8;
6498 this->next->mod(this->next, that, pp, display);
6502 image_transform_png_set_scale_16_add(image_transform *this,
6503 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
6510 return bit_depth > 8;
6515 #define PT ITSTRUCT(scale_16)
6516 #endif /* PNG_READ_SCALE_16_TO_8_SUPPORTED (1.5.4 on) */
6518 #ifdef PNG_READ_16_TO_8_SUPPORTED /* the default before 1.5.4 */
6519 /* png_set_strip_16 */
6521 image_transform_png_set_strip_16_set(PNG_CONST image_transform *this,
6522 transform_display *that, png_structp pp, png_infop pi)
6524 png_set_strip_16(pp);
6525 this->next->set(this->next, that, pp, pi);
6529 image_transform_png_set_strip_16_mod(PNG_CONST image_transform *this,
6530 image_pixel *that, png_const_structp pp,
6531 PNG_CONST transform_display *display)
6533 if (that->bit_depth == 16)
6535 that->sample_depth = that->bit_depth = 8;
6536 if (that->red_sBIT > 8) that->red_sBIT = 8;
6537 if (that->green_sBIT > 8) that->green_sBIT = 8;
6538 if (that->blue_sBIT > 8) that->blue_sBIT = 8;
6539 if (that->alpha_sBIT > 8) that->alpha_sBIT = 8;
6541 /* Prior to 1.5.4 png_set_strip_16 would use an 'accurate' method if this
6542 * configuration option is set. From 1.5.4 the flag is never set and the
6543 * 'scale' API (above) must be used.
6545 # ifdef PNG_READ_ACCURATE_SCALE_SUPPORTED
6546 # if PNG_LIBPNG_VER >= 10504
6547 # error PNG_READ_ACCURATE_SCALE should not be set
6550 /* The strip 16 algorithm drops the low 8 bits rather than calculating
6551 * 1/257, so we need to adjust the permitted errors appropriately:
6552 * Notice that this is only relevant prior to the addition of the
6553 * png_set_scale_16 API in 1.5.4 (but 1.5.4+ always defines the above!)
6556 PNG_CONST double d = (255-128.5)/65535;
6565 this->next->mod(this->next, that, pp, display);
6569 image_transform_png_set_strip_16_add(image_transform *this,
6570 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
6577 return bit_depth > 8;
6582 #define PT ITSTRUCT(strip_16)
6583 #endif /* PNG_READ_16_TO_8_SUPPORTED */
6585 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
6586 /* png_set_strip_alpha */
6588 image_transform_png_set_strip_alpha_set(PNG_CONST image_transform *this,
6589 transform_display *that, png_structp pp, png_infop pi)
6591 png_set_strip_alpha(pp);
6592 this->next->set(this->next, that, pp, pi);
6596 image_transform_png_set_strip_alpha_mod(PNG_CONST image_transform *this,
6597 image_pixel *that, png_const_structp pp,
6598 PNG_CONST transform_display *display)
6600 if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
6601 that->colour_type = PNG_COLOR_TYPE_GRAY;
6602 else if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
6603 that->colour_type = PNG_COLOR_TYPE_RGB;
6605 that->have_tRNS = 0;
6608 this->next->mod(this->next, that, pp, display);
6612 image_transform_png_set_strip_alpha_add(image_transform *this,
6613 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
6620 return (colour_type & PNG_COLOR_MASK_ALPHA) != 0;
6625 #define PT ITSTRUCT(strip_alpha)
6626 #endif /* PNG_READ_STRIP_ALPHA_SUPPORTED */
6628 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
6629 /* png_set_rgb_to_gray(png_structp, int err_action, double red, double green)
6630 * png_set_rgb_to_gray_fixed(png_structp, int err_action, png_fixed_point red,
6631 * png_fixed_point green)
6632 * png_get_rgb_to_gray_status
6634 * The 'default' test here uses values known to be used inside libpng:
6640 * These values are being retained for compatibility, along with the somewhat
6641 * broken truncation calculation in the fast-and-inaccurate code path. Older
6642 * versions of libpng will fail the accuracy tests below because they use the
6643 * truncation algorithm everywhere.
6645 #define data ITDATA(rgb_to_gray)
6648 double gamma; /* File gamma to use in processing */
6650 /* The following are the parameters for png_set_rgb_to_gray: */
6651 # ifdef PNG_FLOATING_POINT_SUPPORTED
6653 double green_to_set;
6655 png_fixed_point red_to_set;
6656 png_fixed_point green_to_set;
6659 /* The actual coefficients: */
6660 double red_coefficient;
6661 double green_coefficient;
6662 double blue_coefficient;
6664 /* Set if the coeefficients have been overridden. */
6665 int coefficients_overridden;
6668 #undef image_transform_ini
6669 #define image_transform_ini image_transform_png_set_rgb_to_gray_ini
6671 image_transform_png_set_rgb_to_gray_ini(PNG_CONST image_transform *this,
6672 transform_display *that)
6674 png_modifier *pm = that->pm;
6675 PNG_CONST color_encoding *e = pm->current_encoding;
6679 /* Since we check the encoding this flag must be set: */
6680 pm->test_uses_encoding = 1;
6682 /* If 'e' is not NULL chromaticity information is present and either a cHRM
6683 * or an sRGB chunk will be inserted.
6687 /* Coefficients come from the encoding, but may need to be normalized to a
6688 * white point Y of 1.0
6690 PNG_CONST double whiteY = e->red.Y + e->green.Y + e->blue.Y;
6692 data.red_coefficient = e->red.Y;
6693 data.green_coefficient = e->green.Y;
6694 data.blue_coefficient = e->blue.Y;
6698 data.red_coefficient /= whiteY;
6699 data.green_coefficient /= whiteY;
6700 data.blue_coefficient /= whiteY;
6706 /* The default (built in) coeffcients, as above: */
6707 data.red_coefficient = 6968 / 32768.;
6708 data.green_coefficient = 23434 / 32768.;
6709 data.blue_coefficient = 2366 / 32768.;
6712 data.gamma = pm->current_gamma;
6714 /* If not set then the calculations assume linear encoding (implicitly): */
6715 if (data.gamma == 0)
6718 /* The arguments to png_set_rgb_to_gray can override the coefficients implied
6719 * by the color space encoding. If doing exhaustive checks do the override
6720 * in each case, otherwise do it randomly.
6722 if (pm->test_exhaustive)
6724 /* First time in coefficients_overridden is 0, the following sets it to 1,
6725 * so repeat if it is set. If a test fails this may mean we subsequently
6726 * skip a non-override test, ignore that.
6728 data.coefficients_overridden = !data.coefficients_overridden;
6729 pm->repeat = data.coefficients_overridden != 0;
6733 data.coefficients_overridden = random_choice();
6735 if (data.coefficients_overridden)
6737 /* These values override the color encoding defaults, simply use random
6744 data.green_coefficient = total = (ru & 0xffff) / 65535.;
6746 data.red_coefficient = (1 - total) * (ru & 0xffff) / 65535.;
6747 total += data.red_coefficient;
6748 data.blue_coefficient = 1 - total;
6750 # ifdef PNG_FLOATING_POINT_SUPPORTED
6751 data.red_to_set = data.red_coefficient;
6752 data.green_to_set = data.green_coefficient;
6754 data.red_to_set = fix(data.red_coefficient);
6755 data.green_to_set = fix(data.green_coefficient);
6758 /* The following just changes the error messages: */
6759 pm->encoding_ignored = 1;
6764 data.red_to_set = -1;
6765 data.green_to_set = -1;
6768 /* Adjust the error limit in the png_modifier because of the larger errors
6769 * produced in the digitization during the gamma handling.
6771 if (data.gamma != 1) /* Use gamma tables */
6773 if (that->this.bit_depth == 16 || pm->assume_16_bit_calculations)
6775 /* The computations have the form:
6777 * r * rc + g * gc + b * bc
6779 * Each component of which is +/-1/65535 from the gamma_to_1 table
6780 * lookup, resulting in a base error of +/-6. The gamma_from_1
6781 * conversion adds another +/-2 in the 16-bit case and
6782 * +/-(1<<(15-PNG_MAX_GAMMA_8)) in the 8-bit case.
6784 that->pm->limit += pow(
6785 # if PNG_MAX_GAMMA_8 < 14
6786 (that->this.bit_depth == 16 ? 8. :
6787 6. + (1<<(15-PNG_MAX_GAMMA_8)))
6791 /65535, data.gamma);
6796 /* Rounding to 8 bits in the linear space causes massive errors which
6797 * will trigger the error check in transform_range_check. Fix that
6798 * here by taking the gamma encoding into account.
6800 * When DIGITIZE is set because a pre-1.7 version of libpng is being
6801 * tested allow a bigger slack.
6803 * NOTE: this magic number was determined by experiment to be 1.1 (when
6804 * using fixed point arithmetic). There's no great merit to the value
6805 * below, however it only affects the limit used for checking for
6806 * internal calculation errors, not the actual limit imposed by
6807 * pngvalid on the output errors.
6809 that->pm->limit += pow(
6821 /* With no gamma correction a large error comes from the truncation of the
6822 * calculation in the 8 bit case, allow for that here.
6824 if (that->this.bit_depth != 16 && !pm->assume_16_bit_calculations)
6825 that->pm->limit += 4E-3;
6830 image_transform_png_set_rgb_to_gray_set(PNG_CONST image_transform *this,
6831 transform_display *that, png_structp pp, png_infop pi)
6833 PNG_CONST int error_action = 1; /* no error, no defines in png.h */
6835 # ifdef PNG_FLOATING_POINT_SUPPORTED
6836 png_set_rgb_to_gray(pp, error_action, data.red_to_set, data.green_to_set);
6838 png_set_rgb_to_gray_fixed(pp, error_action, data.red_to_set,
6842 # ifdef PNG_READ_cHRM_SUPPORTED
6843 if (that->pm->current_encoding != 0)
6845 /* We have an encoding so a cHRM chunk may have been set; if so then
6846 * check that the libpng APIs give the correct (X,Y,Z) values within
6847 * some margin of error for the round trip through the chromaticity
6850 # ifdef PNG_FLOATING_POINT_SUPPORTED
6851 # define API_function png_get_cHRM_XYZ
6852 # define API_form "FP"
6853 # define API_type double
6854 # define API_cvt(x) (x)
6856 # define API_function png_get_cHRM_XYZ_fixed
6857 # define API_form "fixed"
6858 # define API_type png_fixed_point
6859 # define API_cvt(x) ((double)(x)/PNG_FP_1)
6862 API_type rX, gX, bX;
6863 API_type rY, gY, bY;
6864 API_type rZ, gZ, bZ;
6866 if ((API_function(pp, pi, &rX, &rY, &rZ, &gX, &gY, &gZ, &bX, &bY, &bZ)
6867 & PNG_INFO_cHRM) != 0)
6871 color_encoding e, o;
6873 /* Expect libpng to return a normalized result, but the original
6874 * color space encoding may not be normalized.
6876 modifier_current_encoding(that->pm, &o);
6877 normalize_color_encoding(&o);
6879 /* Sanity check the pngvalid code - the coefficients should match
6880 * the normalized Y values of the encoding unless they were
6883 if (data.red_to_set == -1 && data.green_to_set == -1 &&
6884 (fabs(o.red.Y - data.red_coefficient) > DBL_EPSILON ||
6885 fabs(o.green.Y - data.green_coefficient) > DBL_EPSILON ||
6886 fabs(o.blue.Y - data.blue_coefficient) > DBL_EPSILON))
6887 png_error(pp, "internal pngvalid cHRM coefficient error");
6889 /* Generate a colour space encoding. */
6890 e.gamma = o.gamma; /* not used */
6891 e.red.X = API_cvt(rX);
6892 e.red.Y = API_cvt(rY);
6893 e.red.Z = API_cvt(rZ);
6894 e.green.X = API_cvt(gX);
6895 e.green.Y = API_cvt(gY);
6896 e.green.Z = API_cvt(gZ);
6897 e.blue.X = API_cvt(bX);
6898 e.blue.Y = API_cvt(bY);
6899 e.blue.Z = API_cvt(bZ);
6901 /* This should match the original one from the png_modifier, within
6902 * the range permitted by the libpng fixed point representation.
6905 el = "-"; /* Set to element name with error */
6907 # define CHECK(col,x)\
6909 double err = fabs(o.col.x - e.col.x);\
6913 el = #col "(" #x ")";\
6927 /* Here in both fixed and floating cases to check the values read
6928 * from the cHRm chunk. PNG uses fixed point in the cHRM chunk, so
6929 * we can't expect better than +/-.5E-5 on the result, allow 1E-5.
6936 pos = safecat(buffer, sizeof buffer, pos, API_form);
6937 pos = safecat(buffer, sizeof buffer, pos, " cHRM ");
6938 pos = safecat(buffer, sizeof buffer, pos, el);
6939 pos = safecat(buffer, sizeof buffer, pos, " error: ");
6940 pos = safecatd(buffer, sizeof buffer, pos, maxe, 7);
6941 pos = safecat(buffer, sizeof buffer, pos, " ");
6942 /* Print the color space without the gamma value: */
6943 pos = safecat_color_encoding(buffer, sizeof buffer, pos, &o, 0);
6944 pos = safecat(buffer, sizeof buffer, pos, " -> ");
6945 pos = safecat_color_encoding(buffer, sizeof buffer, pos, &e, 0);
6947 png_error(pp, buffer);
6951 # endif /* READ_cHRM */
6953 this->next->set(this->next, that, pp, pi);
6957 image_transform_png_set_rgb_to_gray_mod(PNG_CONST image_transform *this,
6958 image_pixel *that, png_const_structp pp,
6959 PNG_CONST transform_display *display)
6961 if ((that->colour_type & PNG_COLOR_MASK_COLOR) != 0)
6965 if (that->colour_type == PNG_COLOR_TYPE_PALETTE)
6966 image_pixel_convert_PLTE(that);
6968 /* Image now has RGB channels... */
6971 PNG_CONST png_modifier *pm = display->pm;
6972 const unsigned int sample_depth = that->sample_depth;
6973 const unsigned int calc_depth = (pm->assume_16_bit_calculations ? 16 :
6975 const unsigned int gamma_depth = (sample_depth == 16 ? 16 :
6976 (pm->assume_16_bit_calculations ? PNG_MAX_GAMMA_8 : sample_depth));
6979 double rlo, rhi, glo, ghi, blo, bhi, graylo, grayhi;
6981 /* Do this using interval arithmetic, otherwise it is too difficult to
6982 * handle the errors correctly.
6984 * To handle the gamma correction work out the upper and lower bounds
6985 * of the digitized value. Assume rounding here - normally the values
6986 * will be identical after this operation if there is only one
6987 * transform, feel free to delete the png_error checks on this below in
6988 * the future (this is just me trying to ensure it works!)
6990 r = rlo = rhi = that->redf;
6992 rlo = digitize(rlo, calc_depth, 1/*round*/);
6994 rhi = digitize(rhi, calc_depth, 1/*round*/);
6996 g = glo = ghi = that->greenf;
6997 glo -= that->greene;
6998 glo = digitize(glo, calc_depth, 1/*round*/);
6999 ghi += that->greene;
7000 ghi = digitize(ghi, calc_depth, 1/*round*/);
7002 b = blo = bhi = that->bluef;
7004 blo = digitize(blo, calc_depth, 1/*round*/);
7005 bhi += that->greene;
7006 bhi = digitize(bhi, calc_depth, 1/*round*/);
7008 isgray = r==g && g==b;
7010 if (data.gamma != 1)
7012 PNG_CONST double power = 1/data.gamma;
7013 PNG_CONST double abse = calc_depth == 16 ? .5/65535 : .5/255;
7015 /* 'abse' is the absolute error permitted in linear calculations. It
7016 * is used here to capture the error permitted in the handling
7017 * (undoing) of the gamma encoding. Once again digitization occurs
7018 * to handle the upper and lower bounds of the values. This is
7019 * where the real errors are introduced.
7022 rlo = digitize(pow(rlo, power)-abse, calc_depth, 1);
7023 rhi = digitize(pow(rhi, power)+abse, calc_depth, 1);
7026 glo = digitize(pow(glo, power)-abse, calc_depth, 1);
7027 ghi = digitize(pow(ghi, power)+abse, calc_depth, 1);
7030 blo = digitize(pow(blo, power)-abse, calc_depth, 1);
7031 bhi = digitize(pow(bhi, power)+abse, calc_depth, 1);
7034 /* Now calculate the actual gray values. Although the error in the
7035 * coefficients depends on whether they were specified on the command
7036 * line (in which case truncation to 15 bits happened) or not (rounding
7037 * was used) the maxium error in an individual coefficient is always
7038 * 1/32768, because even in the rounding case the requirement that
7039 * coefficients add up to 32768 can cause a larger rounding error.
7041 * The only time when rounding doesn't occur in 1.5.5 and later is when
7042 * the non-gamma code path is used for less than 16 bit data.
7044 gray = r * data.red_coefficient + g * data.green_coefficient +
7045 b * data.blue_coefficient;
7048 PNG_CONST int do_round = data.gamma != 1 || calc_depth == 16;
7049 PNG_CONST double ce = 1. / 32768;
7051 graylo = digitize(rlo * (data.red_coefficient-ce) +
7052 glo * (data.green_coefficient-ce) +
7053 blo * (data.blue_coefficient-ce), gamma_depth, do_round);
7057 grayhi = digitize(rhi * (data.red_coefficient+ce) +
7058 ghi * (data.green_coefficient+ce) +
7059 bhi * (data.blue_coefficient+ce), gamma_depth, do_round);
7064 /* And invert the gamma. */
7065 if (data.gamma != 1)
7067 PNG_CONST double power = data.gamma;
7069 gray = pow(gray, power);
7070 graylo = digitize(pow(graylo, power), sample_depth, 1);
7071 grayhi = digitize(pow(grayhi, power), sample_depth, 1);
7074 /* Now the error can be calculated.
7076 * If r==g==b because there is no overall gamma correction libpng
7077 * currently preserves the original value.
7080 err = (that->rede + that->greene + that->bluee)/3;
7084 err = fabs(grayhi-gray);
7085 if (fabs(gray - graylo) > err)
7086 err = fabs(graylo-gray);
7088 /* Check that this worked: */
7089 if (err > pm->limit)
7094 pos = safecat(buffer, sizeof buffer, pos, "rgb_to_gray error ");
7095 pos = safecatd(buffer, sizeof buffer, pos, err, 6);
7096 pos = safecat(buffer, sizeof buffer, pos, " exceeds limit ");
7097 pos = safecatd(buffer, sizeof buffer, pos, pm->limit, 6);
7098 png_error(pp, buffer);
7102 # else /* DIGITIZE */
7104 double r = that->redf;
7105 double re = that->rede;
7106 double g = that->greenf;
7107 double ge = that->greene;
7108 double b = that->bluef;
7109 double be = that->bluee;
7111 /* The true gray case involves no math. */
7112 if (r == g && r == b)
7116 if (err < ge) err = ge;
7117 if (err < be) err = be;
7120 else if (data.gamma == 1)
7122 /* There is no need to do the conversions to and from linear space,
7123 * so the calculation should be a lot more accurate. There is a
7124 * built in 1/32768 error in the coefficients because they only have
7125 * 15 bits and are adjusted to make sure they add up to 32768, so
7126 * the result may have an additional error up to 1/32768. (Note
7127 * that adding the 1/32768 here avoids needing to increase the
7128 * global error limits to take this into account.)
7130 gray = r * data.red_coefficient + g * data.green_coefficient +
7131 b * data.blue_coefficient;
7132 err = re * data.red_coefficient + ge * data.green_coefficient +
7133 be * data.blue_coefficient + 1./32768 + gray * 5 * DBL_EPSILON;
7138 /* The calculation happens in linear space, and this produces much
7139 * wider errors in the encoded space. These are handled here by
7140 * factoring the errors in to the calculation. There are two table
7141 * lookups in the calculation and each introduces a quantization
7142 * error defined by the table size.
7144 PNG_CONST png_modifier *pm = display->pm;
7145 double in_qe = (that->sample_depth > 8 ? .5/65535 : .5/255);
7146 double out_qe = (that->sample_depth > 8 ? .5/65535 :
7147 (pm->assume_16_bit_calculations ? .5/(1<<PNG_MAX_GAMMA_8) :
7149 double rhi, ghi, bhi, grayhi;
7150 double g1 = 1/data.gamma;
7152 rhi = r + re + in_qe; if (rhi > 1) rhi = 1;
7153 r -= re + in_qe; if (r < 0) r = 0;
7154 ghi = g + ge + in_qe; if (ghi > 1) ghi = 1;
7155 g -= ge + in_qe; if (g < 0) g = 0;
7156 bhi = b + be + in_qe; if (bhi > 1) bhi = 1;
7157 b -= be + in_qe; if (b < 0) b = 0;
7159 r = pow(r, g1)*(1-DBL_EPSILON); rhi = pow(rhi, g1)*(1+DBL_EPSILON);
7160 g = pow(g, g1)*(1-DBL_EPSILON); ghi = pow(ghi, g1)*(1+DBL_EPSILON);
7161 b = pow(b, g1)*(1-DBL_EPSILON); bhi = pow(bhi, g1)*(1+DBL_EPSILON);
7163 /* Work out the lower and upper bounds for the gray value in the
7164 * encoded space, then work out an average and error. Remove the
7165 * previously added input quantization error at this point.
7167 gray = r * data.red_coefficient + g * data.green_coefficient +
7168 b * data.blue_coefficient - 1./32768 - out_qe;
7173 gray *= (1 - 6 * DBL_EPSILON);
7174 gray = pow(gray, data.gamma) * (1-DBL_EPSILON);
7177 grayhi = rhi * data.red_coefficient + ghi * data.green_coefficient +
7178 bhi * data.blue_coefficient + 1./32768 + out_qe;
7179 grayhi *= (1 + 6 * DBL_EPSILON);
7183 grayhi = pow(grayhi, data.gamma) * (1+DBL_EPSILON);
7185 err = (grayhi - gray) / 2;
7186 gray = (grayhi + gray) / 2;
7189 err = gray * DBL_EPSILON;
7194 /* Validate that the error is within limits (this has caused
7195 * problems before, it's much easier to detect them here.)
7197 if (err > pm->limit)
7202 pos = safecat(buffer, sizeof buffer, pos, "rgb_to_gray error ");
7203 pos = safecatd(buffer, sizeof buffer, pos, err, 6);
7204 pos = safecat(buffer, sizeof buffer, pos, " exceeds limit ");
7205 pos = safecatd(buffer, sizeof buffer, pos, pm->limit, 6);
7206 png_error(pp, buffer);
7210 # endif /* !DIGITIZE */
7212 that->bluef = that->greenf = that->redf = gray;
7213 that->bluee = that->greene = that->rede = err;
7215 /* The sBIT is the minium of the three colour channel sBITs. */
7216 if (that->red_sBIT > that->green_sBIT)
7217 that->red_sBIT = that->green_sBIT;
7218 if (that->red_sBIT > that->blue_sBIT)
7219 that->red_sBIT = that->blue_sBIT;
7220 that->blue_sBIT = that->green_sBIT = that->red_sBIT;
7222 /* And remove the colour bit in the type: */
7223 if (that->colour_type == PNG_COLOR_TYPE_RGB)
7224 that->colour_type = PNG_COLOR_TYPE_GRAY;
7225 else if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
7226 that->colour_type = PNG_COLOR_TYPE_GRAY_ALPHA;
7229 this->next->mod(this->next, that, pp, display);
7233 image_transform_png_set_rgb_to_gray_add(image_transform *this,
7234 PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
7241 return (colour_type & PNG_COLOR_MASK_COLOR) != 0;
7247 #define PT ITSTRUCT(rgb_to_gray)
7248 #undef image_transform_ini
7249 #define image_transform_ini image_transform_default_ini
7250 #endif /* PNG_READ_RGB_TO_GRAY_SUPPORTED */
7252 #ifdef PNG_READ_BACKGROUND_SUPPORTED
7253 /* png_set_background(png_structp, png_const_color_16p background_color,
7254 * int background_gamma_code, int need_expand, double background_gamma)
7255 * png_set_background_fixed(png_structp, png_const_color_16p background_color,
7256 * int background_gamma_code, int need_expand,
7257 * png_fixed_point background_gamma)
7259 * This ignores the gamma (at present.)
7261 #define data ITDATA(background)
7262 static image_pixel data;
7265 image_transform_png_set_background_set(PNG_CONST image_transform *this,
7266 transform_display *that, png_structp pp, png_infop pi)
7268 png_byte colour_type, bit_depth;
7269 png_byte random_bytes[8]; /* 8 bytes - 64 bits - the biggest pixel */
7273 /* We need a background colour, because we don't know exactly what transforms
7274 * have been set we have to supply the colour in the original file format and
7275 * so we need to know what that is! The background colour is stored in the
7276 * transform_display.
7278 RANDOMIZE(random_bytes);
7280 /* Read the random value, for colour type 3 the background colour is actually
7281 * expressed as a 24bit rgb, not an index.
7283 colour_type = that->this.colour_type;
7284 if (colour_type == 3)
7286 colour_type = PNG_COLOR_TYPE_RGB;
7288 expand = 0; /* passing in an RGB not a pixel index */
7293 bit_depth = that->this.bit_depth;
7297 image_pixel_init(&data, random_bytes, colour_type,
7298 bit_depth, 0/*x*/, 0/*unused: palette*/);
7300 /* Extract the background colour from this image_pixel, but make sure the
7301 * unused fields of 'back' are garbage.
7305 if (colour_type & PNG_COLOR_MASK_COLOR)
7307 back.red = (png_uint_16)data.red;
7308 back.green = (png_uint_16)data.green;
7309 back.blue = (png_uint_16)data.blue;
7313 back.gray = (png_uint_16)data.red;
7315 # ifdef PNG_FLOATING_POINT_SUPPORTED
7316 png_set_background(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
7318 png_set_background_fixed(pp, &back, PNG_BACKGROUND_GAMMA_FILE, expand, 0);
7321 this->next->set(this->next, that, pp, pi);
7325 image_transform_png_set_background_mod(PNG_CONST image_transform *this,
7326 image_pixel *that, png_const_structp pp,
7327 PNG_CONST transform_display *display)
7329 /* Check for tRNS first: */
7330 if (that->have_tRNS && that->colour_type != PNG_COLOR_TYPE_PALETTE)
7331 image_pixel_add_alpha(that, &display->this);
7333 /* This is only necessary if the alpha value is less than 1. */
7334 if (that->alphaf < 1)
7336 /* Now we do the background calculation without any gamma correction. */
7337 if (that->alphaf <= 0)
7339 that->redf = data.redf;
7340 that->greenf = data.greenf;
7341 that->bluef = data.bluef;
7343 that->rede = data.rede;
7344 that->greene = data.greene;
7345 that->bluee = data.bluee;
7347 that->red_sBIT= data.red_sBIT;
7348 that->green_sBIT= data.green_sBIT;
7349 that->blue_sBIT= data.blue_sBIT;
7352 else /* 0 < alpha < 1 */
7354 double alf = 1 - that->alphaf;
7356 that->redf = that->redf * that->alphaf + data.redf * alf;
7357 that->rede = that->rede * that->alphaf + data.rede * alf +
7359 that->greenf = that->greenf * that->alphaf + data.greenf * alf;
7360 that->greene = that->greene * that->alphaf + data.greene * alf +
7362 that->bluef = that->bluef * that->alphaf + data.bluef * alf;
7363 that->bluee = that->bluee * that->alphaf + data.bluee * alf +
7367 /* Remove the alpha type and set the alpha (not in that order.) */
7371 if (that->colour_type == PNG_COLOR_TYPE_RGB_ALPHA)
7372 that->colour_type = PNG_COLOR_TYPE_RGB;
7373 else if (that->colour_type == PNG_COLOR_TYPE_GRAY_ALPHA)
7374 that->colour_type = PNG_COLOR_TYPE_GRAY;
7375 /* PNG_COLOR_TYPE_PALETTE is not changed */
7378 this->next->mod(this->next, that, pp, display);
7381 #define image_transform_png_set_background_add image_transform_default_add
7386 #define PT ITSTRUCT(background)
7387 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
7389 /* This may just be 'end' if all the transforms are disabled! */
7390 static image_transform *PNG_CONST image_transform_first = &PT;
7393 transform_enable(PNG_CONST char *name)
7395 /* Everything starts out enabled, so if we see an 'enable' disabled
7396 * everything else the first time round.
7398 static int all_disabled = 0;
7400 image_transform *list = image_transform_first;
7402 while (list != &image_transform_end)
7404 if (strcmp(list->name, name) == 0)
7409 else if (!all_disabled)
7419 fprintf(stderr, "pngvalid: --transform-enable=%s: unknown transform\n",
7426 transform_disable(PNG_CONST char *name)
7428 image_transform *list = image_transform_first;
7430 while (list != &image_transform_end)
7432 if (strcmp(list->name, name) == 0)
7441 fprintf(stderr, "pngvalid: --transform-disable=%s: unknown transform\n",
7447 image_transform_reset_count(void)
7449 image_transform *next = image_transform_first;
7452 while (next != &image_transform_end)
7454 next->local_use = 0;
7460 /* This can only happen if we every have more than 32 transforms (excluding
7461 * the end) in the list.
7463 if (count > 32) abort();
7467 image_transform_test_counter(png_uint_32 counter, unsigned int max)
7469 /* Test the list to see if there is any point contining, given a current
7470 * counter and a 'max' value.
7472 image_transform *next = image_transform_first;
7474 while (next != &image_transform_end)
7476 /* For max 0 or 1 continue until the counter overflows: */
7479 /* Continue if any entry hasn't reacked the max. */
7480 if (max > 1 && next->local_use < max)
7485 return max <= 1 && counter == 0;
7489 image_transform_add(PNG_CONST image_transform **this, unsigned int max,
7490 png_uint_32 counter, char *name, size_t sizeof_name, size_t *pos,
7491 png_byte colour_type, png_byte bit_depth)
7493 for (;;) /* until we manage to add something */
7496 image_transform *list;
7498 /* Find the next counter value, if the counter is zero this is the start
7499 * of the list. This routine always returns the current counter (not the
7500 * next) so it returns 0 at the end and expects 0 at the beginning.
7502 if (counter == 0) /* first time */
7504 image_transform_reset_count();
7508 counter = random_32();
7510 else /* advance the counter */
7514 case 0: ++counter; break;
7515 case 1: counter <<= 1; break;
7516 default: counter = random_32(); break;
7520 /* Now add all these items, if possible */
7521 *this = &image_transform_end;
7522 list = image_transform_first;
7525 /* Go through the whole list adding anything that the counter selects: */
7526 while (list != &image_transform_end)
7528 if ((counter & mask) != 0 && list->enable &&
7529 (max == 0 || list->local_use < max))
7531 /* Candidate to add: */
7532 if (list->add(list, this, colour_type, bit_depth) || max == 0)
7534 /* Added, so add to the name too. */
7535 *pos = safecat(name, sizeof_name, *pos, " +");
7536 *pos = safecat(name, sizeof_name, *pos, list->name);
7541 /* Not useful and max>0, so remove it from *this: */
7545 /* And, since we know it isn't useful, stop it being added again
7548 list->local_use = max;
7556 /* Now if anything was added we have something to do. */
7557 if (*this != &image_transform_end)
7560 /* Nothing added, but was there anything in there to add? */
7561 if (!image_transform_test_counter(counter, max))
7566 #ifdef THIS_IS_THE_PROFORMA
7568 image_transform_png_set_@_set(PNG_CONST image_transform *this,
7569 transform_display *that, png_structp pp, png_infop pi)
7572 this->next->set(this->next, that, pp, pi);
7576 image_transform_png_set_@_mod(PNG_CONST image_transform *this,
7577 image_pixel *that, png_const_structp pp,
7578 PNG_CONST transform_display *display)
7580 this->next->mod(this->next, that, pp, display);
7584 image_transform_png_set_@_add(image_transform *this,
7585 PNG_CONST image_transform **that, char *name, size_t sizeof_name,
7586 size_t *pos, png_byte colour_type, png_byte bit_depth)
7591 *pos = safecat(name, sizeof_name, *pos, " +@");
7599 /* png_set_quantize(png_structp, png_colorp palette, int num_palette,
7600 * int maximum_colors, png_const_uint_16p histogram, int full_quantize)
7602 * Very difficult to validate this!
7606 /* The data layout transforms are handled by swapping our own channel data,
7607 * necessarily these need to happen at the end of the transform list because the
7608 * semantic of the channels changes after these are executed. Some of these,
7609 * like set_shift and set_packing, can't be done at present because they change
7610 * the layout of the data at the sub-sample level so sample() won't get the
7613 /* png_set_invert_alpha */
7619 /* png_set_swap_alpha */
7625 /* png_set_filler, (png_structp png_ptr, png_uint_32 filler, int flags)); */
7628 /* png_set_add_alpha, (png_structp png_ptr, png_uint_32 filler, int flags)); */
7631 /* png_set_packing */
7634 /* png_set_packswap */
7637 /* png_set_invert_mono */
7640 /* png_set_shift(png_structp, png_const_color_8p true_bits) */
7644 perform_transform_test(png_modifier *pm)
7646 png_byte colour_type = 0;
7647 png_byte bit_depth = 0;
7648 unsigned int palette_number = 0;
7650 while (next_format(&colour_type, &bit_depth, &palette_number, 0))
7652 png_uint_32 counter = 0;
7656 base_pos = safecat(name, sizeof name, 0, "transform:");
7660 size_t pos = base_pos;
7661 PNG_CONST image_transform *list = 0;
7663 /* 'max' is currently hardwired to '1'; this should be settable on the
7666 counter = image_transform_add(&list, 1/*max*/, counter,
7667 name, sizeof name, &pos, colour_type, bit_depth);
7672 /* The command line can change this to checking interlaced images. */
7676 transform_test(pm, FILEID(colour_type, bit_depth, palette_number,
7677 pm->interlace_type, 0, 0, 0), list, name);
7686 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
7688 /********************************* GAMMA TESTS ********************************/
7689 #ifdef PNG_READ_GAMMA_SUPPORTED
7690 /* Reader callbacks and implementations, where they differ from the standard
7693 typedef struct gamma_display
7695 standard_display this;
7700 double screen_gamma;
7701 double background_gamma;
7704 int use_input_precision;
7708 png_color_16 background_color;
7710 /* Local variables */
7716 #define ALPHA_MODE_OFFSET 4
7719 gamma_display_init(gamma_display *dp, png_modifier *pm, png_uint_32 id,
7720 double file_gamma, double screen_gamma, png_byte sbit, int threshold_test,
7721 int use_input_precision, int scale16, int expand16,
7722 int do_background, PNG_CONST png_color_16 *pointer_to_the_background_color,
7723 double background_gamma)
7725 /* Standard fields */
7726 standard_display_init(&dp->this, &pm->this, id, 0/*do_interlace*/,
7727 pm->use_update_info);
7729 /* Parameter fields */
7731 dp->file_gamma = file_gamma;
7732 dp->screen_gamma = screen_gamma;
7733 dp->background_gamma = background_gamma;
7735 dp->threshold_test = threshold_test;
7736 dp->use_input_precision = use_input_precision;
7737 dp->scale16 = scale16;
7738 dp->expand16 = expand16;
7739 dp->do_background = do_background;
7740 if (do_background && pointer_to_the_background_color != 0)
7741 dp->background_color = *pointer_to_the_background_color;
7743 memset(&dp->background_color, 0, sizeof dp->background_color);
7745 /* Local variable fields */
7746 dp->maxerrout = dp->maxerrpc = dp->maxerrabs = 0;
7750 gamma_info_imp(gamma_display *dp, png_structp pp, png_infop pi)
7752 /* Reuse the standard stuff as appropriate. */
7753 standard_info_part1(&dp->this, pp, pi);
7755 /* If requested strip 16 to 8 bits - this is handled automagically below
7756 * because the output bit depth is read from the library. Note that there
7757 * are interactions with sBIT but, internally, libpng makes sbit at most
7758 * PNG_MAX_GAMMA_8 when doing the following.
7761 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
7762 png_set_scale_16(pp);
7764 /* The following works both in 1.5.4 and earlier versions: */
7765 # ifdef PNG_READ_16_TO_8_SUPPORTED
7766 png_set_strip_16(pp);
7768 png_error(pp, "scale16 (16 to 8 bit conversion) not supported");
7773 # ifdef PNG_READ_EXPAND_16_SUPPORTED
7774 png_set_expand_16(pp);
7776 png_error(pp, "expand16 (8 to 16 bit conversion) not supported");
7779 if (dp->do_background >= ALPHA_MODE_OFFSET)
7781 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
7783 /* This tests the alpha mode handling, if supported. */
7784 int mode = dp->do_background - ALPHA_MODE_OFFSET;
7786 /* The gamma value is the output gamma, and is in the standard,
7787 * non-inverted, represenation. It provides a default for the PNG file
7788 * gamma, but since the file has a gAMA chunk this does not matter.
7790 PNG_CONST double sg = dp->screen_gamma;
7791 # ifndef PNG_FLOATING_POINT_SUPPORTED
7792 PNG_CONST png_fixed_point g = fix(sg);
7795 # ifdef PNG_FLOATING_POINT_SUPPORTED
7796 png_set_alpha_mode(pp, mode, sg);
7798 png_set_alpha_mode_fixed(pp, mode, g);
7801 /* However, for the standard Porter-Duff algorithm the output defaults
7802 * to be linear, so if the test requires non-linear output it must be
7805 if (mode == PNG_ALPHA_STANDARD && sg != 1)
7807 # ifdef PNG_FLOATING_POINT_SUPPORTED
7808 png_set_gamma(pp, sg, dp->file_gamma);
7810 png_fixed_point f = fix(dp->file_gamma);
7811 png_set_gamma_fixed(pp, g, f);
7816 png_error(pp, "alpha mode handling not supported");
7822 /* Set up gamma processing. */
7823 # ifdef PNG_FLOATING_POINT_SUPPORTED
7824 png_set_gamma(pp, dp->screen_gamma, dp->file_gamma);
7827 png_fixed_point s = fix(dp->screen_gamma);
7828 png_fixed_point f = fix(dp->file_gamma);
7829 png_set_gamma_fixed(pp, s, f);
7833 if (dp->do_background)
7835 # ifdef PNG_READ_BACKGROUND_SUPPORTED
7836 /* NOTE: this assumes the caller provided the correct background gamma!
7838 PNG_CONST double bg = dp->background_gamma;
7839 # ifndef PNG_FLOATING_POINT_SUPPORTED
7840 PNG_CONST png_fixed_point g = fix(bg);
7843 # ifdef PNG_FLOATING_POINT_SUPPORTED
7844 png_set_background(pp, &dp->background_color, dp->do_background,
7845 0/*need_expand*/, bg);
7847 png_set_background_fixed(pp, &dp->background_color,
7848 dp->do_background, 0/*need_expand*/, g);
7851 png_error(pp, "png_set_background not supported");
7857 int i = dp->this.use_update_info;
7858 /* Always do one call, even if use_update_info is 0. */
7860 png_read_update_info(pp, pi);
7864 /* Now we may get a different cbRow: */
7865 standard_info_part2(&dp->this, pp, pi, 1 /*images*/);
7868 static void PNGCBAPI
7869 gamma_info(png_structp pp, png_infop pi)
7871 gamma_info_imp(voidcast(gamma_display*, png_get_progressive_ptr(pp)), pp,
7875 /* Validate a single component value - the routine gets the input and output
7876 * sample values as unscaled PNG component values along with a cache of all the
7877 * information required to validate the values.
7879 typedef struct validate_info
7881 png_const_structp pp;
7884 int use_input_precision;
7887 unsigned int sbit_max;
7888 unsigned int isbit_shift;
7889 unsigned int outmax;
7891 double gamma_correction; /* Overall correction required. */
7892 double file_inverse; /* Inverse of file gamma. */
7893 double screen_gamma;
7894 double screen_inverse; /* Inverse of screen gamma. */
7896 double background_red; /* Linear background value, red or gray. */
7897 double background_green;
7898 double background_blue;
7904 double maxout_total; /* Total including quantization error */
7911 init_validate_info(validate_info *vi, gamma_display *dp, png_const_structp pp,
7912 int in_depth, int out_depth)
7914 PNG_CONST unsigned int outmax = (1U<<out_depth)-1;
7919 if (dp->sbit > 0 && dp->sbit < in_depth)
7921 vi->sbit = dp->sbit;
7922 vi->isbit_shift = in_depth - dp->sbit;
7927 vi->sbit = (png_byte)in_depth;
7928 vi->isbit_shift = 0;
7931 vi->sbit_max = (1U << vi->sbit)-1;
7933 /* This mimics the libpng threshold test, '0' is used to prevent gamma
7934 * correction in the validation test.
7936 vi->screen_gamma = dp->screen_gamma;
7937 if (fabs(vi->screen_gamma-1) < PNG_GAMMA_THRESHOLD)
7938 vi->screen_gamma = vi->screen_inverse = 0;
7940 vi->screen_inverse = 1/vi->screen_gamma;
7942 vi->use_input_precision = dp->use_input_precision;
7943 vi->outmax = outmax;
7944 vi->maxabs = abserr(dp->pm, in_depth, out_depth);
7945 vi->maxpc = pcerr(dp->pm, in_depth, out_depth);
7946 vi->maxcalc = calcerr(dp->pm, in_depth, out_depth);
7947 vi->maxout = outerr(dp->pm, in_depth, out_depth);
7948 vi->outquant = output_quantization_factor(dp->pm, in_depth, out_depth);
7949 vi->maxout_total = vi->maxout + vi->outquant * .5;
7950 vi->outlog = outlog(dp->pm, in_depth, out_depth);
7952 if ((dp->this.colour_type & PNG_COLOR_MASK_ALPHA) != 0 ||
7953 (dp->this.colour_type == 3 && dp->this.is_transparent))
7955 vi->do_background = dp->do_background;
7957 if (vi->do_background != 0)
7959 PNG_CONST double bg_inverse = 1/dp->background_gamma;
7962 /* Caller must at least put the gray value into the red channel */
7963 r = dp->background_color.red; r /= outmax;
7964 g = dp->background_color.green; g /= outmax;
7965 b = dp->background_color.blue; b /= outmax;
7968 /* libpng doesn't do this optimization, if we do pngvalid will fail.
7970 if (fabs(bg_inverse-1) >= PNG_GAMMA_THRESHOLD)
7973 r = pow(r, bg_inverse);
7974 g = pow(g, bg_inverse);
7975 b = pow(b, bg_inverse);
7978 vi->background_red = r;
7979 vi->background_green = g;
7980 vi->background_blue = b;
7984 vi->do_background = 0;
7986 if (vi->do_background == 0)
7987 vi->background_red = vi->background_green = vi->background_blue = 0;
7989 vi->gamma_correction = 1/(dp->file_gamma*dp->screen_gamma);
7990 if (fabs(vi->gamma_correction-1) < PNG_GAMMA_THRESHOLD)
7991 vi->gamma_correction = 0;
7993 vi->file_inverse = 1/dp->file_gamma;
7994 if (fabs(vi->file_inverse-1) < PNG_GAMMA_THRESHOLD)
7995 vi->file_inverse = 0;
7997 vi->scale16 = dp->scale16;
8000 /* This function handles composition of a single non-alpha component. The
8001 * argument is the input sample value, in the range 0..1, and the alpha value.
8002 * The result is the composed, linear, input sample. If alpha is less than zero
8003 * this is the alpha component and the function should not be called!
8006 gamma_component_compose(int do_background, double input_sample, double alpha,
8007 double background, int *compose)
8009 switch (do_background)
8011 #ifdef PNG_READ_BACKGROUND_SUPPORTED
8012 case PNG_BACKGROUND_GAMMA_SCREEN:
8013 case PNG_BACKGROUND_GAMMA_FILE:
8014 case PNG_BACKGROUND_GAMMA_UNIQUE:
8015 /* Standard PNG background processing. */
8020 input_sample = input_sample * alpha + background * (1-alpha);
8021 if (compose != NULL)
8026 input_sample = background;
8031 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
8032 case ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD:
8033 case ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN:
8034 /* The components are premultiplied in either case and the output is
8035 * gamma encoded (to get standard Porter-Duff we expect the output
8036 * gamma to be set to 1.0!)
8038 case ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED:
8039 /* The optimization is that the partial-alpha entries are linear
8040 * while the opaque pixels are gamma encoded, but this only affects the
8047 input_sample *= alpha;
8048 if (compose != NULL)
8059 /* Standard cases where no compositing is done (so the component
8060 * value is already correct.)
8068 return input_sample;
8071 /* This API returns the encoded *input* component, in the range 0..1 */
8073 gamma_component_validate(PNG_CONST char *name, PNG_CONST validate_info *vi,
8074 PNG_CONST unsigned int id, PNG_CONST unsigned int od,
8075 PNG_CONST double alpha /* <0 for the alpha channel itself */,
8076 PNG_CONST double background /* component background value */)
8078 PNG_CONST unsigned int isbit = id >> vi->isbit_shift;
8079 PNG_CONST unsigned int sbit_max = vi->sbit_max;
8080 PNG_CONST unsigned int outmax = vi->outmax;
8081 PNG_CONST int do_background = vi->do_background;
8085 /* First check on the 'perfect' result obtained from the digitized input
8086 * value, id, and compare this against the actual digitized result, 'od'.
8087 * 'i' is the input result in the range 0..1:
8089 i = isbit; i /= sbit_max;
8091 /* Check for the fast route: if we don't do any background composition or if
8092 * this is the alpha channel ('alpha' < 0) or if the pixel is opaque then
8093 * just use the gamma_correction field to correct to the final output gamma.
8095 if (alpha == 1 /* opaque pixel component */ || !do_background
8096 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
8097 || do_background == ALPHA_MODE_OFFSET + PNG_ALPHA_PNG
8099 || (alpha < 0 /* alpha channel */
8100 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
8101 && do_background != ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN
8105 /* Then get the gamma corrected version of 'i' and compare to 'od', any
8106 * error less than .5 is insignificant - just quantization of the output
8107 * value to the nearest digital value (nevertheless the error is still
8108 * recorded - it's interesting ;-)
8110 double encoded_sample = i;
8111 double encoded_error;
8113 /* alpha less than 0 indicates the alpha channel, which is always linear
8115 if (alpha >= 0 && vi->gamma_correction > 0)
8116 encoded_sample = pow(encoded_sample, vi->gamma_correction);
8117 encoded_sample *= outmax;
8119 encoded_error = fabs(od-encoded_sample);
8121 if (encoded_error > vi->dp->maxerrout)
8122 vi->dp->maxerrout = encoded_error;
8124 if (encoded_error < vi->maxout_total && encoded_error < vi->outlog)
8128 /* The slow route - attempt to do linear calculations. */
8129 /* There may be an error, or background processing is required, so calculate
8130 * the actual sample values - unencoded light intensity values. Note that in
8131 * practice these are not completely unencoded because they include a
8132 * 'viewing correction' to decrease or (normally) increase the perceptual
8133 * contrast of the image. There's nothing we can do about this - we don't
8134 * know what it is - so assume the unencoded value is perceptually linear.
8137 double input_sample = i; /* In range 0..1 */
8138 double output, error, encoded_sample, encoded_error;
8139 double es_lo, es_hi;
8140 int compose = 0; /* Set to one if composition done */
8141 int output_is_encoded; /* Set if encoded to screen gamma */
8142 int log_max_error = 1; /* Check maximum error values */
8143 png_const_charp pass = 0; /* Reason test passes (or 0 for fail) */
8145 /* Convert to linear light (with the above caveat.) The alpha channel is
8152 if (vi->file_inverse > 0)
8153 input_sample = pow(input_sample, vi->file_inverse);
8155 /* Handle the compose processing: */
8157 input_sample = gamma_component_compose(do_background, input_sample,
8158 alpha, background, &tcompose);
8164 /* And similarly for the output value, but we need to check the background
8165 * handling to linearize it correctly.
8170 output_is_encoded = vi->screen_gamma > 0;
8172 if (alpha < 0) /* The alpha channel */
8174 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
8175 if (do_background != ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN)
8178 /* In all other cases the output alpha channel is linear already,
8179 * don't log errors here, they are much larger in linear data.
8181 output_is_encoded = 0;
8186 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
8187 else /* A component */
8189 if (do_background == ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED &&
8190 alpha < 1) /* the optimized case - linear output */
8192 if (alpha > 0) log_max_error = 0;
8193 output_is_encoded = 0;
8198 if (output_is_encoded)
8199 output = pow(output, vi->screen_gamma);
8201 /* Calculate (or recalculate) the encoded_sample value and repeat the
8202 * check above (unnecessary if we took the fast route, but harmless.)
8204 encoded_sample = input_sample;
8205 if (output_is_encoded)
8206 encoded_sample = pow(encoded_sample, vi->screen_inverse);
8207 encoded_sample *= outmax;
8209 encoded_error = fabs(od-encoded_sample);
8211 /* Don't log errors in the alpha channel, or the 'optimized' case,
8212 * neither are significant to the overall perception.
8214 if (log_max_error && encoded_error > vi->dp->maxerrout)
8215 vi->dp->maxerrout = encoded_error;
8217 if (encoded_error < vi->maxout_total)
8219 if (encoded_error < vi->outlog)
8222 /* Test passed but error is bigger than the log limit, record why the
8225 pass = "less than maxout:\n";
8228 /* i: the original input value in the range 0..1
8230 * pngvalid calculations:
8231 * input_sample: linear result; i linearized and composed, range 0..1
8232 * encoded_sample: encoded result; input_sample scaled to ouput bit depth
8234 * libpng calculations:
8235 * output: linear result; od scaled to 0..1 and linearized
8236 * od: encoded result from libpng
8239 /* Now we have the numbers for real errors, both absolute values as as a
8240 * percentage of the correct value (output):
8242 error = fabs(input_sample-output);
8244 if (log_max_error && error > vi->dp->maxerrabs)
8245 vi->dp->maxerrabs = error;
8247 /* The following is an attempt to ignore the tendency of quantization to
8248 * dominate the percentage errors for lower result values:
8250 if (log_max_error && input_sample > .5)
8252 double percentage_error = error/input_sample;
8253 if (percentage_error > vi->dp->maxerrpc)
8254 vi->dp->maxerrpc = percentage_error;
8257 /* Now calculate the digitization limits for 'encoded_sample' using the
8258 * 'max' values. Note that maxout is in the encoded space but maxpc and
8259 * maxabs are in linear light space.
8261 * First find the maximum error in linear light space, range 0..1:
8264 double tmp = input_sample * vi->maxpc;
8265 if (tmp < vi->maxabs) tmp = vi->maxabs;
8266 /* If 'compose' is true the composition was done in linear space using
8267 * integer arithmetic. This introduces an extra error of +/- 0.5 (at
8268 * least) in the integer space used. 'maxcalc' records this, taking
8269 * into account the possibility that even for 16 bit output 8 bit space
8270 * may have been used.
8272 if (compose && tmp < vi->maxcalc) tmp = vi->maxcalc;
8274 /* The 'maxout' value refers to the encoded result, to compare with
8275 * this encode input_sample adjusted by the maximum error (tmp) above.
8277 es_lo = encoded_sample - vi->maxout;
8279 if (es_lo > 0 && input_sample-tmp > 0)
8281 double low_value = input_sample-tmp;
8282 if (output_is_encoded)
8283 low_value = pow(low_value, vi->screen_inverse);
8284 low_value *= outmax;
8285 if (low_value < es_lo) es_lo = low_value;
8287 /* Quantize this appropriately: */
8288 es_lo = ceil(es_lo / vi->outquant - .5) * vi->outquant;
8294 es_hi = encoded_sample + vi->maxout;
8296 if (es_hi < outmax && input_sample+tmp < 1)
8298 double high_value = input_sample+tmp;
8299 if (output_is_encoded)
8300 high_value = pow(high_value, vi->screen_inverse);
8301 high_value *= outmax;
8302 if (high_value > es_hi) es_hi = high_value;
8304 es_hi = floor(es_hi / vi->outquant + .5) * vi->outquant;
8311 /* The primary test is that the final encoded value returned by the
8312 * library should be between the two limits (inclusive) that were
8315 if (od >= es_lo && od <= es_hi)
8317 /* The value passes, but we may need to log the information anyway. */
8318 if (encoded_error < vi->outlog)
8322 pass = "within digitization limits:\n";
8326 /* There has been an error in processing, or we need to log this
8329 double is_lo, is_hi;
8331 /* pass is set at this point if either of the tests above would have
8332 * passed. Don't do these additional tests here - just log the
8333 * original [es_lo..es_hi] values.
8335 if (pass == 0 && vi->use_input_precision && vi->dp->sbit)
8337 /* Ok, something is wrong - this actually happens in current libpng
8338 * 16-to-8 processing. Assume that the input value (id, adjusted
8339 * for sbit) can be anywhere between value-.5 and value+.5 - quite a
8340 * large range if sbit is low.
8342 * NOTE: at present because the libpng gamma table stuff has been
8343 * changed to use a rounding algorithm to correct errors in 8-bit
8344 * calculations the precise sbit calculation (a shift) has been
8345 * lost. This can result in up to a +/-1 error in the presence of
8346 * an sbit less than the bit depth.
8348 # if PNG_LIBPNG_VER < 10700
8349 # define SBIT_ERROR .5
8351 # define SBIT_ERROR 1.
8353 double tmp = (isbit - SBIT_ERROR)/sbit_max;
8358 else if (alpha >= 0 && vi->file_inverse > 0 && tmp < 1)
8359 tmp = pow(tmp, vi->file_inverse);
8361 tmp = gamma_component_compose(do_background, tmp, alpha, background,
8364 if (output_is_encoded && tmp > 0 && tmp < 1)
8365 tmp = pow(tmp, vi->screen_inverse);
8367 is_lo = ceil(outmax * tmp - vi->maxout_total);
8372 tmp = (isbit + SBIT_ERROR)/sbit_max;
8377 else if (alpha >= 0 && vi->file_inverse > 0 && tmp < 1)
8378 tmp = pow(tmp, vi->file_inverse);
8380 tmp = gamma_component_compose(do_background, tmp, alpha, background,
8383 if (output_is_encoded && tmp > 0 && tmp < 1)
8384 tmp = pow(tmp, vi->screen_inverse);
8386 is_hi = floor(outmax * tmp + vi->maxout_total);
8391 if (!(od < is_lo || od > is_hi))
8393 if (encoded_error < vi->outlog)
8396 pass = "within input precision limits:\n";
8399 /* One last chance. If this is an alpha channel and the 16to8
8400 * option has been used and 'inaccurate' scaling is used then the
8401 * bit reduction is obtained by simply using the top 8 bits of the
8404 * This is only done for older libpng versions when the 'inaccurate'
8405 * (chop) method of scaling was used.
8407 # ifndef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
8408 # if PNG_LIBPNG_VER < 10504
8409 /* This may be required for other components in the future,
8410 * but at present the presence of gamma correction effectively
8411 * prevents the errors in the component scaling (I don't quite
8412 * understand why, but since it's better this way I care not
8413 * to ask, JB 20110419.)
8415 if (pass == 0 && alpha < 0 && vi->scale16 && vi->sbit > 8 &&
8416 vi->sbit + vi->isbit_shift == 16)
8418 tmp = ((id >> 8) - .5)/255;
8422 is_lo = ceil(outmax * tmp - vi->maxout_total);
8423 if (is_lo < 0) is_lo = 0;
8429 tmp = ((id >> 8) + .5)/255;
8433 is_hi = floor(outmax * tmp + vi->maxout_total);
8434 if (is_hi > outmax) is_hi = outmax;
8440 if (!(od < is_lo || od > is_hi))
8442 if (encoded_error < vi->outlog)
8445 pass = "within 8 bit limits:\n";
8451 else /* !use_input_precision */
8452 is_lo = es_lo, is_hi = es_hi;
8454 /* Attempt to output a meaningful error/warning message: the message
8455 * output depends on the background/composite operation being performed
8456 * because this changes what parameters were actually used above.
8460 /* Need either 1/255 or 1/65535 precision here; 3 or 6 decimal
8461 * places. Just use outmax to work out which.
8463 int precision = (outmax >= 1000 ? 6 : 3);
8464 int use_input=1, use_background=0, do_compose=0;
8468 pos = safecat(msg, sizeof msg, pos, "\n\t");
8470 /* Set up the various flags, the output_is_encoded flag above
8471 * is also used below. do_compose is just a double check.
8473 switch (do_background)
8475 # ifdef PNG_READ_BACKGROUND_SUPPORTED
8476 case PNG_BACKGROUND_GAMMA_SCREEN:
8477 case PNG_BACKGROUND_GAMMA_FILE:
8478 case PNG_BACKGROUND_GAMMA_UNIQUE:
8479 use_background = (alpha >= 0 && alpha < 1);
8482 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
8483 case ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD:
8484 case ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN:
8485 case ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED:
8486 # endif /* ALPHA_MODE_SUPPORTED */
8487 do_compose = (alpha > 0 && alpha < 1);
8488 use_input = (alpha != 0);
8495 /* Check the 'compose' flag */
8496 if (compose != do_compose)
8497 png_error(vi->pp, "internal error (compose)");
8499 /* 'name' is the component name */
8500 pos = safecat(msg, sizeof msg, pos, name);
8501 pos = safecat(msg, sizeof msg, pos, "(");
8502 pos = safecatn(msg, sizeof msg, pos, id);
8503 if (use_input || pass != 0/*logging*/)
8507 /* sBIT has reduced the precision of the input: */
8508 pos = safecat(msg, sizeof msg, pos, ", sbit(");
8509 pos = safecatn(msg, sizeof msg, pos, vi->sbit);
8510 pos = safecat(msg, sizeof msg, pos, "): ");
8511 pos = safecatn(msg, sizeof msg, pos, isbit);
8513 pos = safecat(msg, sizeof msg, pos, "/");
8514 /* The output is either "id/max" or "id sbit(sbit): isbit/max" */
8515 pos = safecatn(msg, sizeof msg, pos, vi->sbit_max);
8517 pos = safecat(msg, sizeof msg, pos, ")");
8519 /* A component may have been multiplied (in linear space) by the
8520 * alpha value, 'compose' says whether this is relevant.
8522 if (compose || pass != 0)
8524 /* If any form of composition is being done report our
8525 * calculated linear value here (the code above doesn't record
8526 * the input value before composition is performed, so what
8527 * gets reported is the value after composition.)
8529 if (use_input || pass != 0)
8531 if (vi->file_inverse > 0)
8533 pos = safecat(msg, sizeof msg, pos, "^");
8534 pos = safecatd(msg, sizeof msg, pos, vi->file_inverse, 2);
8538 pos = safecat(msg, sizeof msg, pos, "[linear]");
8540 pos = safecat(msg, sizeof msg, pos, "*(alpha)");
8541 pos = safecatd(msg, sizeof msg, pos, alpha, precision);
8544 /* Now record the *linear* background value if it was used
8545 * (this function is not passed the original, non-linear,
8546 * value but it is contained in the test name.)
8550 pos = safecat(msg, sizeof msg, pos, use_input ? "+" : " ");
8551 pos = safecat(msg, sizeof msg, pos, "(background)");
8552 pos = safecatd(msg, sizeof msg, pos, background, precision);
8553 pos = safecat(msg, sizeof msg, pos, "*");
8554 pos = safecatd(msg, sizeof msg, pos, 1-alpha, precision);
8558 /* Report the calculated value (input_sample) and the linearized
8559 * libpng value (output) unless this is just a component gamma
8562 if (compose || alpha < 0 || pass != 0)
8564 pos = safecat(msg, sizeof msg, pos,
8565 pass != 0 ? " =\n\t" : " = ");
8566 pos = safecatd(msg, sizeof msg, pos, input_sample, precision);
8567 pos = safecat(msg, sizeof msg, pos, " (libpng: ");
8568 pos = safecatd(msg, sizeof msg, pos, output, precision);
8569 pos = safecat(msg, sizeof msg, pos, ")");
8571 /* Finally report the output gamma encoding, if any. */
8572 if (output_is_encoded)
8574 pos = safecat(msg, sizeof msg, pos, " ^");
8575 pos = safecatd(msg, sizeof msg, pos, vi->screen_inverse, 2);
8576 pos = safecat(msg, sizeof msg, pos, "(to screen) =");
8580 pos = safecat(msg, sizeof msg, pos, " [screen is linear] =");
8583 if ((!compose && alpha >= 0) || pass != 0)
8585 if (pass != 0) /* logging */
8586 pos = safecat(msg, sizeof msg, pos, "\n\t[overall:");
8588 /* This is the non-composition case, the internal linear
8589 * values are irrelevant (though the log below will reveal
8590 * them.) Output a much shorter warning/error message and report
8591 * the overall gamma correction.
8593 if (vi->gamma_correction > 0)
8595 pos = safecat(msg, sizeof msg, pos, " ^");
8596 pos = safecatd(msg, sizeof msg, pos, vi->gamma_correction, 2);
8597 pos = safecat(msg, sizeof msg, pos, "(gamma correction) =");
8601 pos = safecat(msg, sizeof msg, pos,
8602 " [no gamma correction] =");
8605 pos = safecat(msg, sizeof msg, pos, "]");
8608 /* This is our calculated encoded_sample which should (but does
8611 pos = safecat(msg, sizeof msg, pos, pass != 0 ? "\n\t" : " ");
8612 pos = safecatd(msg, sizeof msg, pos, is_lo, 1);
8613 pos = safecat(msg, sizeof msg, pos, " < ");
8614 pos = safecatd(msg, sizeof msg, pos, encoded_sample, 1);
8615 pos = safecat(msg, sizeof msg, pos, " (libpng: ");
8616 pos = safecatn(msg, sizeof msg, pos, od);
8617 pos = safecat(msg, sizeof msg, pos, ")");
8618 pos = safecat(msg, sizeof msg, pos, "/");
8619 pos = safecatn(msg, sizeof msg, pos, outmax);
8620 pos = safecat(msg, sizeof msg, pos, " < ");
8621 pos = safecatd(msg, sizeof msg, pos, is_hi, 1);
8623 if (pass == 0) /* The error condition */
8625 # ifdef PNG_WARNINGS_SUPPORTED
8626 png_warning(vi->pp, msg);
8628 store_warning(vi->pp, msg);
8632 else /* logging this value */
8633 store_verbose(&vi->dp->pm->this, vi->pp, pass, msg);
8642 gamma_image_validate(gamma_display *dp, png_const_structp pp,
8645 /* Get some constants derived from the input and output file formats: */
8646 PNG_CONST png_store* PNG_CONST ps = dp->this.ps;
8647 PNG_CONST png_byte in_ct = dp->this.colour_type;
8648 PNG_CONST png_byte in_bd = dp->this.bit_depth;
8649 PNG_CONST png_uint_32 w = dp->this.w;
8650 PNG_CONST png_uint_32 h = dp->this.h;
8651 PNG_CONST size_t cbRow = dp->this.cbRow;
8652 PNG_CONST png_byte out_ct = png_get_color_type(pp, pi);
8653 PNG_CONST png_byte out_bd = png_get_bit_depth(pp, pi);
8655 /* There are three sources of error, firstly the quantization in the
8656 * file encoding, determined by sbit and/or the file depth, secondly
8657 * the output (screen) gamma and thirdly the output file encoding.
8659 * Since this API receives the screen and file gamma in double
8660 * precision it is possible to calculate an exact answer given an input
8661 * pixel value. Therefore we assume that the *input* value is exact -
8662 * sample/maxsample - calculate the corresponding gamma corrected
8663 * output to the limits of double precision arithmetic and compare with
8664 * what libpng returns.
8666 * Since the library must quantize the output to 8 or 16 bits there is
8667 * a fundamental limit on the accuracy of the output of +/-.5 - this
8668 * quantization limit is included in addition to the other limits
8669 * specified by the paramaters to the API. (Effectively, add .5
8672 * The behavior of the 'sbit' paramter is defined by section 12.5
8673 * (sample depth scaling) of the PNG spec. That section forces the
8674 * decoder to assume that the PNG values have been scaled if sBIT is
8677 * png-sample = floor( input-sample * (max-out/max-in) + .5);
8679 * This means that only a subset of the possible PNG values should
8680 * appear in the input. However, the spec allows the encoder to use a
8681 * variety of approximations to the above and doesn't require any
8682 * restriction of the values produced.
8684 * Nevertheless the spec requires that the upper 'sBIT' bits of the
8685 * value stored in a PNG file be the original sample bits.
8686 * Consequently the code below simply scales the top sbit bits by
8687 * (1<<sbit)-1 to obtain an original sample value.
8689 * Because there is limited precision in the input it is arguable that
8690 * an acceptable result is any valid result from input-.5 to input+.5.
8691 * The basic tests below do not do this, however if 'use_input_precision'
8692 * is set a subsequent test is performed above.
8694 PNG_CONST unsigned int samples_per_pixel = (out_ct & 2U) ? 3U : 1U;
8697 PNG_CONST store_palette_entry *in_palette = dp->this.palette;
8698 PNG_CONST int in_is_transparent = dp->this.is_transparent;
8699 int out_npalette = -1;
8700 int out_is_transparent = 0; /* Just refers to the palette case */
8701 store_palette out_palette;
8704 /* Check for row overwrite errors */
8705 store_image_check(dp->this.ps, pp, 0);
8707 /* Supply the input and output sample depths here - 8 for an indexed image,
8708 * otherwise the bit depth.
8710 init_validate_info(&vi, dp, pp, in_ct==3?8:in_bd, out_ct==3?8:out_bd);
8712 processing = (vi.gamma_correction > 0 && !dp->threshold_test)
8713 || in_bd != out_bd || in_ct != out_ct || vi.do_background;
8715 /* TODO: FIX THIS: MAJOR BUG! If the transformations all happen inside
8716 * the palette there is no way of finding out, because libpng fails to
8717 * update the palette on png_read_update_info. Indeed, libpng doesn't
8718 * even do the required work until much later, when it doesn't have any
8719 * info pointer. Oops. For the moment 'processing' is turned off if
8720 * out_ct is palette.
8722 if (in_ct == 3 && out_ct == 3)
8725 if (processing && out_ct == 3)
8726 out_is_transparent = read_palette(out_palette, &out_npalette, pp, pi);
8730 png_const_bytep pRow = store_image_row(ps, pp, 0, y);
8731 png_byte std[STANDARD_ROWMAX];
8733 transform_row(pp, std, in_ct, in_bd, y);
8741 double alpha = 1; /* serves as a flag value */
8743 /* Record the palette index for index images. */
8744 PNG_CONST unsigned int in_index =
8745 in_ct == 3 ? sample(std, 3, in_bd, x, 0) : 256;
8746 PNG_CONST unsigned int out_index =
8747 out_ct == 3 ? sample(std, 3, out_bd, x, 0) : 256;
8749 /* Handle input alpha - png_set_background will cause the output
8750 * alpha to disappear so there is nothing to check.
8752 if ((in_ct & PNG_COLOR_MASK_ALPHA) != 0 || (in_ct == 3 &&
8755 PNG_CONST unsigned int input_alpha = in_ct == 3 ?
8756 dp->this.palette[in_index].alpha :
8757 sample(std, in_ct, in_bd, x, samples_per_pixel);
8759 unsigned int output_alpha = 65536 /* as a flag value */;
8763 if (out_is_transparent)
8764 output_alpha = out_palette[out_index].alpha;
8767 else if ((out_ct & PNG_COLOR_MASK_ALPHA) != 0)
8768 output_alpha = sample(pRow, out_ct, out_bd, x,
8771 if (output_alpha != 65536)
8772 alpha = gamma_component_validate("alpha", &vi, input_alpha,
8773 output_alpha, -1/*alpha*/, 0/*background*/);
8775 else /* no alpha in output */
8777 /* This is a copy of the calculation of 'i' above in order to
8778 * have the alpha value to use in the background calculation.
8780 alpha = input_alpha >> vi.isbit_shift;
8781 alpha /= vi.sbit_max;
8785 /* Handle grayscale or RGB components. */
8786 if ((in_ct & PNG_COLOR_MASK_COLOR) == 0) /* grayscale */
8787 (void)gamma_component_validate("gray", &vi,
8788 sample(std, in_ct, in_bd, x, 0),
8789 sample(pRow, out_ct, out_bd, x, 0), alpha/*component*/,
8791 else /* RGB or palette */
8793 (void)gamma_component_validate("red", &vi,
8794 in_ct == 3 ? in_palette[in_index].red :
8795 sample(std, in_ct, in_bd, x, 0),
8796 out_ct == 3 ? out_palette[out_index].red :
8797 sample(pRow, out_ct, out_bd, x, 0),
8798 alpha/*component*/, vi.background_red);
8800 (void)gamma_component_validate("green", &vi,
8801 in_ct == 3 ? in_palette[in_index].green :
8802 sample(std, in_ct, in_bd, x, 1),
8803 out_ct == 3 ? out_palette[out_index].green :
8804 sample(pRow, out_ct, out_bd, x, 1),
8805 alpha/*component*/, vi.background_green);
8807 (void)gamma_component_validate("blue", &vi,
8808 in_ct == 3 ? in_palette[in_index].blue :
8809 sample(std, in_ct, in_bd, x, 2),
8810 out_ct == 3 ? out_palette[out_index].blue :
8811 sample(pRow, out_ct, out_bd, x, 2),
8812 alpha/*component*/, vi.background_blue);
8817 else if (memcmp(std, pRow, cbRow) != 0)
8821 /* No transform is expected on the threshold tests. */
8822 sprintf(msg, "gamma: below threshold row %lu changed",
8827 } /* row (y) loop */
8829 dp->this.ps->validated = 1;
8832 static void PNGCBAPI
8833 gamma_end(png_structp ppIn, png_infop pi)
8835 png_const_structp pp = ppIn;
8836 gamma_display *dp = voidcast(gamma_display*, png_get_progressive_ptr(pp));
8838 if (!dp->this.speed)
8839 gamma_image_validate(dp, pp, pi);
8841 dp->this.ps->validated = 1;
8844 /* A single test run checking a gamma transformation.
8846 * maxabs: maximum absolute error as a fraction
8847 * maxout: maximum output error in the output units
8848 * maxpc: maximum percentage error (as a percentage)
8851 gamma_test(png_modifier *pmIn, PNG_CONST png_byte colour_typeIn,
8852 PNG_CONST png_byte bit_depthIn, PNG_CONST int palette_numberIn,
8853 PNG_CONST int interlace_typeIn,
8854 PNG_CONST double file_gammaIn, PNG_CONST double screen_gammaIn,
8855 PNG_CONST png_byte sbitIn, PNG_CONST int threshold_testIn,
8856 PNG_CONST char *name,
8857 PNG_CONST int use_input_precisionIn, PNG_CONST int scale16In,
8858 PNG_CONST int expand16In, PNG_CONST int do_backgroundIn,
8859 PNG_CONST png_color_16 *bkgd_colorIn, double bkgd_gammaIn)
8862 context(&pmIn->this, fault);
8864 gamma_display_init(&d, pmIn, FILEID(colour_typeIn, bit_depthIn,
8865 palette_numberIn, interlace_typeIn, 0, 0, 0),
8866 file_gammaIn, screen_gammaIn, sbitIn,
8867 threshold_testIn, use_input_precisionIn, scale16In,
8868 expand16In, do_backgroundIn, bkgd_colorIn, bkgd_gammaIn);
8874 gama_modification gama_mod;
8875 srgb_modification srgb_mod;
8876 sbit_modification sbit_mod;
8878 /* For the moment don't use the png_modifier support here. */
8879 d.pm->encoding_counter = 0;
8880 modifier_set_encoding(d.pm); /* Just resets everything */
8881 d.pm->current_gamma = d.file_gamma;
8883 /* Make an appropriate modifier to set the PNG file gamma to the
8884 * given gamma value and the sBIT chunk to the given precision.
8886 d.pm->modifications = NULL;
8887 gama_modification_init(&gama_mod, d.pm, d.file_gamma);
8888 srgb_modification_init(&srgb_mod, d.pm, 127 /*delete*/);
8890 sbit_modification_init(&sbit_mod, d.pm, d.sbit);
8892 modification_reset(d.pm->modifications);
8894 /* Get a png_struct for writing the image. */
8895 pp = set_modifier_for_read(d.pm, &pi, d.this.id, name);
8896 standard_palette_init(&d.this);
8898 /* Introduce the correct read function. */
8899 if (d.pm->this.progressive)
8901 /* Share the row function with the standard implementation. */
8902 png_set_progressive_read_fn(pp, &d, gamma_info, progressive_row,
8905 /* Now feed data into the reader until we reach the end: */
8906 modifier_progressive_read(d.pm, pp, pi);
8910 /* modifier_read expects a png_modifier* */
8911 png_set_read_fn(pp, d.pm, modifier_read);
8913 /* Check the header values: */
8914 png_read_info(pp, pi);
8916 /* Process the 'info' requirements. Only one image is generated */
8917 gamma_info_imp(&d, pp, pi);
8919 sequential_row(&d.this, pp, pi, -1, 0);
8922 gamma_image_validate(&d, pp, pi);
8924 d.this.ps->validated = 1;
8927 modifier_reset(d.pm);
8929 if (d.pm->log && !d.threshold_test && !d.this.speed)
8930 fprintf(stderr, "%d bit %s %s: max error %f (%.2g, %2g%%)\n",
8931 d.this.bit_depth, colour_types[d.this.colour_type], name,
8932 d.maxerrout, d.maxerrabs, 100*d.maxerrpc);
8934 /* Log the summary values too. */
8935 if (d.this.colour_type == 0 || d.this.colour_type == 4)
8937 switch (d.this.bit_depth)
8943 if (d.maxerrout > d.pm->error_gray_2)
8944 d.pm->error_gray_2 = d.maxerrout;
8949 if (d.maxerrout > d.pm->error_gray_4)
8950 d.pm->error_gray_4 = d.maxerrout;
8955 if (d.maxerrout > d.pm->error_gray_8)
8956 d.pm->error_gray_8 = d.maxerrout;
8961 if (d.maxerrout > d.pm->error_gray_16)
8962 d.pm->error_gray_16 = d.maxerrout;
8967 png_error(pp, "bad bit depth (internal: 1)");
8971 else if (d.this.colour_type == 2 || d.this.colour_type == 6)
8973 switch (d.this.bit_depth)
8977 if (d.maxerrout > d.pm->error_color_8)
8978 d.pm->error_color_8 = d.maxerrout;
8984 if (d.maxerrout > d.pm->error_color_16)
8985 d.pm->error_color_16 = d.maxerrout;
8990 png_error(pp, "bad bit depth (internal: 2)");
8994 else if (d.this.colour_type == 3)
8996 if (d.maxerrout > d.pm->error_indexed)
8997 d.pm->error_indexed = d.maxerrout;
9002 modifier_reset(voidcast(png_modifier*,(void*)fault));
9005 static void gamma_threshold_test(png_modifier *pm, png_byte colour_type,
9006 png_byte bit_depth, int interlace_type, double file_gamma,
9007 double screen_gamma)
9011 pos = safecat(name, sizeof name, pos, "threshold ");
9012 pos = safecatd(name, sizeof name, pos, file_gamma, 3);
9013 pos = safecat(name, sizeof name, pos, "/");
9014 pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
9016 (void)gamma_test(pm, colour_type, bit_depth, 0/*palette*/, interlace_type,
9017 file_gamma, screen_gamma, 0/*sBIT*/, 1/*threshold test*/, name,
9018 0 /*no input precision*/,
9019 0 /*no scale16*/, 0 /*no expand16*/, 0 /*no background*/, 0 /*hence*/,
9020 0 /*no background gamma*/);
9024 perform_gamma_threshold_tests(png_modifier *pm)
9026 png_byte colour_type = 0;
9027 png_byte bit_depth = 0;
9028 unsigned int palette_number = 0;
9030 /* Don't test more than one instance of each palette - it's pointless, in
9031 * fact this test is somewhat excessive since libpng doesn't make this
9032 * decision based on colour type or bit depth!
9034 while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
9035 if (palette_number == 0)
9037 double test_gamma = 1.0;
9038 while (test_gamma >= .4)
9040 /* There's little point testing the interlacing vs non-interlacing,
9041 * but this can be set from the command line.
9043 gamma_threshold_test(pm, colour_type, bit_depth, pm->interlace_type,
9044 test_gamma, 1/test_gamma);
9048 /* And a special test for sRGB */
9049 gamma_threshold_test(pm, colour_type, bit_depth, pm->interlace_type,
9057 static void gamma_transform_test(png_modifier *pm,
9058 PNG_CONST png_byte colour_type, PNG_CONST png_byte bit_depth,
9059 PNG_CONST int palette_number,
9060 PNG_CONST int interlace_type, PNG_CONST double file_gamma,
9061 PNG_CONST double screen_gamma, PNG_CONST png_byte sbit,
9062 PNG_CONST int use_input_precision, PNG_CONST int scale16)
9067 if (sbit != bit_depth && sbit != 0)
9069 pos = safecat(name, sizeof name, pos, "sbit(");
9070 pos = safecatn(name, sizeof name, pos, sbit);
9071 pos = safecat(name, sizeof name, pos, ") ");
9075 pos = safecat(name, sizeof name, pos, "gamma ");
9078 pos = safecat(name, sizeof name, pos, "16to8 ");
9080 pos = safecatd(name, sizeof name, pos, file_gamma, 3);
9081 pos = safecat(name, sizeof name, pos, "->");
9082 pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
9084 gamma_test(pm, colour_type, bit_depth, palette_number, interlace_type,
9085 file_gamma, screen_gamma, sbit, 0, name, use_input_precision,
9086 scale16, pm->test_gamma_expand16, 0 , 0, 0);
9089 static void perform_gamma_transform_tests(png_modifier *pm)
9091 png_byte colour_type = 0;
9092 png_byte bit_depth = 0;
9093 unsigned int palette_number = 0;
9095 while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
9099 for (i=0; i<pm->ngamma_tests; ++i) for (j=0; j<pm->ngamma_tests; ++j)
9102 gamma_transform_test(pm, colour_type, bit_depth, palette_number,
9103 pm->interlace_type, 1/pm->gammas[i], pm->gammas[j], 0/*sBIT*/,
9104 pm->use_input_precision, 0 /*do not scale16*/);
9112 static void perform_gamma_sbit_tests(png_modifier *pm)
9116 /* The only interesting cases are colour and grayscale, alpha is ignored here
9117 * for overall speed. Only bit depths where sbit is less than the bit depth
9120 for (sbit=pm->sbitlow; sbit<(1<<READ_BDHI); ++sbit)
9122 png_byte colour_type = 0, bit_depth = 0;
9123 unsigned int npalette = 0;
9125 while (next_format(&colour_type, &bit_depth, &npalette, 1/*gamma*/))
9126 if ((colour_type & PNG_COLOR_MASK_ALPHA) == 0 &&
9127 ((colour_type == 3 && sbit < 8) ||
9128 (colour_type != 3 && sbit < bit_depth)))
9132 for (i=0; i<pm->ngamma_tests; ++i)
9136 for (j=0; j<pm->ngamma_tests; ++j) if (i != j)
9138 gamma_transform_test(pm, colour_type, bit_depth, npalette,
9139 pm->interlace_type, 1/pm->gammas[i], pm->gammas[j],
9140 sbit, pm->use_input_precision_sbit, 0 /*scale16*/);
9150 /* Note that this requires a 16 bit source image but produces 8 bit output, so
9151 * we only need the 16bit write support, but the 16 bit images are only
9152 * generated if DO_16BIT is defined.
9155 static void perform_gamma_scale16_tests(png_modifier *pm)
9157 # ifndef PNG_MAX_GAMMA_8
9158 # define PNG_MAX_GAMMA_8 11
9160 # define SBIT_16_TO_8 PNG_MAX_GAMMA_8
9161 /* Include the alpha cases here. Note that sbit matches the internal value
9162 * used by the library - otherwise we will get spurious errors from the
9163 * internal sbit style approximation.
9165 * The threshold test is here because otherwise the 16 to 8 conversion will
9166 * proceed *without* gamma correction, and the tests above will fail (but not
9167 * by much) - this could be fixed, it only appears with the -g option.
9170 for (i=0; i<pm->ngamma_tests; ++i)
9172 for (j=0; j<pm->ngamma_tests; ++j)
9175 fabs(pm->gammas[j]/pm->gammas[i]-1) >= PNG_GAMMA_THRESHOLD)
9177 gamma_transform_test(pm, 0, 16, 0, pm->interlace_type,
9178 1/pm->gammas[i], pm->gammas[j], SBIT_16_TO_8,
9179 pm->use_input_precision_16to8, 1 /*scale16*/);
9184 gamma_transform_test(pm, 2, 16, 0, pm->interlace_type,
9185 1/pm->gammas[i], pm->gammas[j], SBIT_16_TO_8,
9186 pm->use_input_precision_16to8, 1 /*scale16*/);
9191 gamma_transform_test(pm, 4, 16, 0, pm->interlace_type,
9192 1/pm->gammas[i], pm->gammas[j], SBIT_16_TO_8,
9193 pm->use_input_precision_16to8, 1 /*scale16*/);
9198 gamma_transform_test(pm, 6, 16, 0, pm->interlace_type,
9199 1/pm->gammas[i], pm->gammas[j], SBIT_16_TO_8,
9200 pm->use_input_precision_16to8, 1 /*scale16*/);
9208 #endif /* 16 to 8 bit conversion */
9210 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
9211 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
9212 static void gamma_composition_test(png_modifier *pm,
9213 PNG_CONST png_byte colour_type, PNG_CONST png_byte bit_depth,
9214 PNG_CONST int palette_number,
9215 PNG_CONST int interlace_type, PNG_CONST double file_gamma,
9216 PNG_CONST double screen_gamma,
9217 PNG_CONST int use_input_precision, PNG_CONST int do_background,
9218 PNG_CONST int expand_16)
9221 png_const_charp base;
9224 png_color_16 background;
9226 /* Make up a name and get an appropriate background gamma value. */
9227 switch (do_background)
9231 bg = 4; /* should not be used */
9233 case PNG_BACKGROUND_GAMMA_SCREEN:
9234 base = " bckg(Screen):";
9235 bg = 1/screen_gamma;
9237 case PNG_BACKGROUND_GAMMA_FILE:
9238 base = " bckg(File):";
9241 case PNG_BACKGROUND_GAMMA_UNIQUE:
9242 base = " bckg(Unique):";
9243 /* This tests the handling of a unique value, the math is such that the
9244 * value tends to be <1, but is neither screen nor file (even if they
9247 bg = (file_gamma + screen_gamma) / 3;
9249 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
9250 case ALPHA_MODE_OFFSET + PNG_ALPHA_PNG:
9251 base = " alpha(PNG)";
9252 bg = 4; /* should not be used */
9254 case ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD:
9255 base = " alpha(Porter-Duff)";
9256 bg = 4; /* should not be used */
9258 case ALPHA_MODE_OFFSET + PNG_ALPHA_OPTIMIZED:
9259 base = " alpha(Optimized)";
9260 bg = 4; /* should not be used */
9262 case ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN:
9263 base = " alpha(Broken)";
9264 bg = 4; /* should not be used */
9269 /* Use random background values - the background is always presented in the
9270 * output space (8 or 16 bit components).
9272 if (expand_16 || bit_depth == 16)
9274 png_uint_32 r = random_32();
9276 background.red = (png_uint_16)r;
9277 background.green = (png_uint_16)(r >> 16);
9279 background.blue = (png_uint_16)r;
9280 background.gray = (png_uint_16)(r >> 16);
9283 else /* 8 bit colors */
9285 png_uint_32 r = random_32();
9287 background.red = (png_byte)r;
9288 background.green = (png_byte)(r >> 8);
9289 background.blue = (png_byte)(r >> 16);
9290 background.gray = (png_byte)(r >> 24);
9293 background.index = 193; /* rgb(193,193,193) to detect errors */
9294 if (!(colour_type & PNG_COLOR_MASK_COLOR))
9296 /* Grayscale input, we do not convert to RGB (TBD), so we must set the
9297 * background to gray - else libpng seems to fail.
9299 background.red = background.green = background.blue = background.gray;
9302 pos = safecat(name, sizeof name, pos, "gamma ");
9303 pos = safecatd(name, sizeof name, pos, file_gamma, 3);
9304 pos = safecat(name, sizeof name, pos, "->");
9305 pos = safecatd(name, sizeof name, pos, screen_gamma, 3);
9307 pos = safecat(name, sizeof name, pos, base);
9308 if (do_background < ALPHA_MODE_OFFSET)
9310 /* Include the background color and gamma in the name: */
9311 pos = safecat(name, sizeof name, pos, "(");
9312 /* This assumes no expand gray->rgb - the current code won't handle that!
9314 if (colour_type & PNG_COLOR_MASK_COLOR)
9316 pos = safecatn(name, sizeof name, pos, background.red);
9317 pos = safecat(name, sizeof name, pos, ",");
9318 pos = safecatn(name, sizeof name, pos, background.green);
9319 pos = safecat(name, sizeof name, pos, ",");
9320 pos = safecatn(name, sizeof name, pos, background.blue);
9323 pos = safecatn(name, sizeof name, pos, background.gray);
9324 pos = safecat(name, sizeof name, pos, ")^");
9325 pos = safecatd(name, sizeof name, pos, bg, 3);
9328 gamma_test(pm, colour_type, bit_depth, palette_number, interlace_type,
9329 file_gamma, screen_gamma, 0/*sBIT*/, 0, name, use_input_precision,
9330 0/*strip 16*/, expand_16, do_background, &background, bg);
9335 perform_gamma_composition_tests(png_modifier *pm, int do_background,
9338 png_byte colour_type = 0;
9339 png_byte bit_depth = 0;
9340 unsigned int palette_number = 0;
9342 /* Skip the non-alpha cases - there is no setting of a transparency colour at
9345 while (next_format(&colour_type, &bit_depth, &palette_number, 1/*gamma*/))
9346 if ((colour_type & PNG_COLOR_MASK_ALPHA) != 0)
9350 /* Don't skip the i==j case here - it's relevant. */
9351 for (i=0; i<pm->ngamma_tests; ++i) for (j=0; j<pm->ngamma_tests; ++j)
9353 gamma_composition_test(pm, colour_type, bit_depth, palette_number,
9354 pm->interlace_type, 1/pm->gammas[i], pm->gammas[j],
9355 pm->use_input_precision, do_background, expand_16);
9362 #endif /* READ_BACKGROUND || READ_ALPHA_MODE */
9365 init_gamma_errors(png_modifier *pm)
9367 /* Use -1 to catch tests that were not actually run */
9368 pm->error_gray_2 = pm->error_gray_4 = pm->error_gray_8 = -1.;
9369 pm->error_color_8 = -1.;
9370 pm->error_indexed = -1.;
9371 pm->error_gray_16 = pm->error_color_16 = -1.;
9375 print_one(const char *leader, double err)
9378 printf(" %s %.5f\n", leader, err);
9382 summarize_gamma_errors(png_modifier *pm, png_const_charp who, int low_bit_depth,
9388 printf("\nGamma correction with %s:\n", who);
9391 printf("\nBasic gamma correction:\n");
9395 print_one(" 2 bit gray: ", pm->error_gray_2);
9396 print_one(" 4 bit gray: ", pm->error_gray_4);
9397 print_one(" 8 bit gray: ", pm->error_gray_8);
9398 print_one(" 8 bit color:", pm->error_color_8);
9400 print_one(" indexed: ", pm->error_indexed);
9403 print_one("16 bit gray: ", pm->error_gray_16);
9404 print_one("16 bit color:", pm->error_color_16);
9410 perform_gamma_test(png_modifier *pm, int summary)
9412 /*TODO: remove this*/
9413 /* Save certain values for the temporary overrides below. */
9414 unsigned int calculations_use_input_precision =
9415 pm->calculations_use_input_precision;
9416 # ifdef PNG_READ_BACKGROUND_SUPPORTED
9417 double maxout8 = pm->maxout8;
9420 /* First some arbitrary no-transform tests: */
9421 if (!pm->this.speed && pm->test_gamma_threshold)
9423 perform_gamma_threshold_tests(pm);
9429 /* Now some real transforms. */
9430 if (pm->test_gamma_transform)
9435 printf("Gamma correction error summary\n\n");
9436 printf("The printed value is the maximum error in the pixel values\n");
9437 printf("calculated by the libpng gamma correction code. The error\n");
9438 printf("is calculated as the difference between the output pixel\n");
9439 printf("value (always an integer) and the ideal value from the\n");
9440 printf("libpng specification (typically not an integer).\n\n");
9442 printf("Expect this value to be less than .5 for 8 bit formats,\n");
9443 printf("less than 1 for formats with fewer than 8 bits and a small\n");
9444 printf("number (typically less than 5) for the 16 bit formats.\n");
9445 printf("For performance reasons the value for 16 bit formats\n");
9446 printf("increases when the image file includes an sBIT chunk.\n");
9450 init_gamma_errors(pm);
9451 /*TODO: remove this. Necessary because the current libpng
9452 * implementation works in 8 bits:
9454 if (pm->test_gamma_expand16)
9455 pm->calculations_use_input_precision = 1;
9456 perform_gamma_transform_tests(pm);
9457 if (!calculations_use_input_precision)
9458 pm->calculations_use_input_precision = 0;
9461 summarize_gamma_errors(pm, 0/*who*/, 1/*low bit depth*/, 1/*indexed*/);
9467 /* The sbit tests produce much larger errors: */
9468 if (pm->test_gamma_sbit)
9470 init_gamma_errors(pm);
9471 perform_gamma_sbit_tests(pm);
9474 summarize_gamma_errors(pm, "sBIT", pm->sbitlow < 8U, 1/*indexed*/);
9480 #ifdef DO_16BIT /* Should be READ_16BIT_SUPPORTED */
9481 if (pm->test_gamma_scale16)
9483 /* The 16 to 8 bit strip operations: */
9484 init_gamma_errors(pm);
9485 perform_gamma_scale16_tests(pm);
9490 printf("\nGamma correction with 16 to 8 bit reduction:\n");
9491 printf(" 16 bit gray: %.5f\n", pm->error_gray_16);
9492 printf(" 16 bit color: %.5f\n", pm->error_color_16);
9501 #ifdef PNG_READ_BACKGROUND_SUPPORTED
9502 if (pm->test_gamma_background)
9504 init_gamma_errors(pm);
9506 /*TODO: remove this. Necessary because the current libpng
9507 * implementation works in 8 bits:
9509 if (pm->test_gamma_expand16)
9511 pm->calculations_use_input_precision = 1;
9512 pm->maxout8 = .499; /* because the 16 bit background is smashed */
9514 perform_gamma_composition_tests(pm, PNG_BACKGROUND_GAMMA_UNIQUE,
9515 pm->test_gamma_expand16);
9516 if (!calculations_use_input_precision)
9517 pm->calculations_use_input_precision = 0;
9518 pm->maxout8 = maxout8;
9521 summarize_gamma_errors(pm, "background", 1, 0/*indexed*/);
9528 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
9529 if (pm->test_gamma_alpha_mode)
9533 init_gamma_errors(pm);
9535 /*TODO: remove this. Necessary because the current libpng
9536 * implementation works in 8 bits:
9538 if (pm->test_gamma_expand16)
9539 pm->calculations_use_input_precision = 1;
9540 for (do_background = ALPHA_MODE_OFFSET + PNG_ALPHA_STANDARD;
9541 do_background <= ALPHA_MODE_OFFSET + PNG_ALPHA_BROKEN && !fail(pm);
9543 perform_gamma_composition_tests(pm, do_background,
9544 pm->test_gamma_expand16);
9545 if (!calculations_use_input_precision)
9546 pm->calculations_use_input_precision = 0;
9549 summarize_gamma_errors(pm, "alpha mode", 1, 0/*indexed*/);
9556 #endif /* PNG_READ_GAMMA_SUPPORTED */
9557 #endif /* PNG_READ_SUPPORTED */
9559 /* INTERLACE MACRO VALIDATION */
9560 /* This is copied verbatim from the specification, it is simply the pass
9561 * number in which each pixel in each 8x8 tile appears. The array must
9562 * be indexed adam7[y][x] and notice that the pass numbers are based at
9563 * 1, not 0 - the base libpng uses.
9566 png_byte adam7[8][8] =
9568 { 1,6,4,6,2,6,4,6 },
9569 { 7,7,7,7,7,7,7,7 },
9570 { 5,6,5,6,5,6,5,6 },
9571 { 7,7,7,7,7,7,7,7 },
9572 { 3,6,4,6,3,6,4,6 },
9573 { 7,7,7,7,7,7,7,7 },
9574 { 5,6,5,6,5,6,5,6 },
9578 /* This routine validates all the interlace support macros in png.h for
9579 * a variety of valid PNG widths and heights. It uses a number of similarly
9580 * named internal routines that feed off the above array.
9583 png_pass_start_row(int pass)
9587 for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass)
9593 png_pass_start_col(int pass)
9597 for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass)
9603 png_pass_row_shift(int pass)
9605 int x, y, base=(-1), inc=8;
9607 for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass)
9613 else if (inc == y-base)
9616 inc = y-base, base=y;
9617 else if (inc != y-base)
9618 return 0xff; /* error - more than one 'inc' value! */
9621 if (base == (-1)) return 0xfe; /* error - no row in pass! */
9623 /* The shift is always 1, 2 or 3 - no pass has all the rows! */
9632 /* error - unrecognized 'inc' */
9633 return (inc << 8) + 0xfd;
9637 png_pass_col_shift(int pass)
9639 int x, y, base=(-1), inc=8;
9641 for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass)
9647 else if (inc == x-base)
9650 inc = x-base, base=x;
9651 else if (inc != x-base)
9652 return 0xff; /* error - more than one 'inc' value! */
9655 if (base == (-1)) return 0xfe; /* error - no row in pass! */
9657 /* The shift is always 1, 2 or 3 - no pass has all the rows! */
9660 case 1: return 0; /* pass 7 has all the columns */
9667 /* error - unrecognized 'inc' */
9668 return (inc << 8) + 0xfd;
9672 png_row_from_pass_row(png_uint_32 yIn, int pass)
9674 /* By examination of the array: */
9677 case 0: return yIn * 8;
9678 case 1: return yIn * 8;
9679 case 2: return yIn * 8 + 4;
9680 case 3: return yIn * 4;
9681 case 4: return yIn * 4 + 2;
9682 case 5: return yIn * 2;
9683 case 6: return yIn * 2 + 1;
9687 return 0xff; /* bad pass number */
9691 png_col_from_pass_col(png_uint_32 xIn, int pass)
9693 /* By examination of the array: */
9696 case 0: return xIn * 8;
9697 case 1: return xIn * 8 + 4;
9698 case 2: return xIn * 4;
9699 case 3: return xIn * 4 + 2;
9700 case 4: return xIn * 2;
9701 case 5: return xIn * 2 + 1;
9706 return 0xff; /* bad pass number */
9710 png_row_in_interlace_pass(png_uint_32 y, int pass)
9712 /* Is row 'y' in pass 'pass'? */
9716 for (x=0; x<8; ++x) if (adam7[y][x] == pass)
9723 png_col_in_interlace_pass(png_uint_32 x, int pass)
9725 /* Is column 'x' in pass 'pass'? */
9729 for (y=0; y<8; ++y) if (adam7[y][x] == pass)
9736 png_pass_rows(png_uint_32 height, int pass)
9738 png_uint_32 tiles = height>>3;
9739 png_uint_32 rows = 0;
9744 for (y=0; y<8; ++y) for (x=0; x<8; ++x) if (adam7[y][x] == pass)
9747 if (y < height) ++rows;
9748 break; /* i.e. break the 'x', column, loop. */
9755 png_pass_cols(png_uint_32 width, int pass)
9757 png_uint_32 tiles = width>>3;
9758 png_uint_32 cols = 0;
9763 for (x=0; x<8; ++x) for (y=0; y<8; ++y) if (adam7[y][x] == pass)
9766 if (x < width) ++cols;
9767 break; /* i.e. break the 'y', row, loop. */
9774 perform_interlace_macro_validation(void)
9776 /* The macros to validate, first those that depend only on pass:
9778 * PNG_PASS_START_ROW(pass)
9779 * PNG_PASS_START_COL(pass)
9780 * PNG_PASS_ROW_SHIFT(pass)
9781 * PNG_PASS_COL_SHIFT(pass)
9785 for (pass=0; pass<7; ++pass)
9787 png_uint_32 m, f, v;
9789 m = PNG_PASS_START_ROW(pass);
9790 f = png_pass_start_row(pass);
9793 fprintf(stderr, "PNG_PASS_START_ROW(%d) = %u != %x\n", pass, m, f);
9797 m = PNG_PASS_START_COL(pass);
9798 f = png_pass_start_col(pass);
9801 fprintf(stderr, "PNG_PASS_START_COL(%d) = %u != %x\n", pass, m, f);
9805 m = PNG_PASS_ROW_SHIFT(pass);
9806 f = png_pass_row_shift(pass);
9809 fprintf(stderr, "PNG_PASS_ROW_SHIFT(%d) = %u != %x\n", pass, m, f);
9813 m = PNG_PASS_COL_SHIFT(pass);
9814 f = png_pass_col_shift(pass);
9817 fprintf(stderr, "PNG_PASS_COL_SHIFT(%d) = %u != %x\n", pass, m, f);
9821 /* Macros that depend on the image or sub-image height too:
9823 * PNG_PASS_ROWS(height, pass)
9824 * PNG_PASS_COLS(width, pass)
9825 * PNG_ROW_FROM_PASS_ROW(yIn, pass)
9826 * PNG_COL_FROM_PASS_COL(xIn, pass)
9827 * PNG_ROW_IN_INTERLACE_PASS(y, pass)
9828 * PNG_COL_IN_INTERLACE_PASS(x, pass)
9832 /* First the base 0 stuff: */
9833 m = PNG_ROW_FROM_PASS_ROW(v, pass);
9834 f = png_row_from_pass_row(v, pass);
9837 fprintf(stderr, "PNG_ROW_FROM_PASS_ROW(%u, %d) = %u != %x\n",
9842 m = PNG_COL_FROM_PASS_COL(v, pass);
9843 f = png_col_from_pass_col(v, pass);
9846 fprintf(stderr, "PNG_COL_FROM_PASS_COL(%u, %d) = %u != %x\n",
9851 m = PNG_ROW_IN_INTERLACE_PASS(v, pass);
9852 f = png_row_in_interlace_pass(v, pass);
9855 fprintf(stderr, "PNG_ROW_IN_INTERLACE_PASS(%u, %d) = %u != %x\n",
9860 m = PNG_COL_IN_INTERLACE_PASS(v, pass);
9861 f = png_col_in_interlace_pass(v, pass);
9864 fprintf(stderr, "PNG_COL_IN_INTERLACE_PASS(%u, %d) = %u != %x\n",
9869 /* Then the base 1 stuff: */
9871 m = PNG_PASS_ROWS(v, pass);
9872 f = png_pass_rows(v, pass);
9875 fprintf(stderr, "PNG_PASS_ROWS(%u, %d) = %u != %x\n",
9880 m = PNG_PASS_COLS(v, pass);
9881 f = png_pass_cols(v, pass);
9884 fprintf(stderr, "PNG_PASS_COLS(%u, %d) = %u != %x\n",
9889 /* Move to the next v - the stepping algorithm starts skipping
9890 * values above 1024.
9894 if (v == PNG_UINT_31_MAX)
9898 if (v >= PNG_UINT_31_MAX)
9899 v = PNG_UINT_31_MAX-1;
9905 /* Test color encodings. These values are back-calculated from the published
9906 * chromaticities. The values are accurate to about 14 decimal places; 15 are
9907 * given. These values are much more accurate than the ones given in the spec,
9908 * which typically don't exceed 4 decimal places. This allows testing of the
9909 * libpng code to its theoretical accuracy of 4 decimal places. (If pngvalid
9910 * used the published errors the 'slack' permitted would have to be +/-.5E-4 or
9913 * The png_modifier code assumes that encodings[0] is sRGB and treats it
9914 * specially: do not change the first entry in this list!
9916 static PNG_CONST color_encoding test_encodings[] =
9918 /* sRGB: must be first in this list! */
9920 /*red: */ { 0.412390799265959, 0.212639005871510, 0.019330818715592 },
9921 /*green:*/ { 0.357584339383878, 0.715168678767756, 0.119194779794626 },
9922 /*blue: */ { 0.180480788401834, 0.072192315360734, 0.950532152249660} },
9923 /* Kodak ProPhoto (wide gamut) */
9924 /*gamma:*/ { 1/1.6 /*approximate: uses 1.8 power law compared to sRGB 2.4*/,
9925 /*red: */ { 0.797760489672303, 0.288071128229293, 0.000000000000000 },
9926 /*green:*/ { 0.135185837175740, 0.711843217810102, 0.000000000000000 },
9927 /*blue: */ { 0.031349349581525, 0.000085653960605, 0.825104602510460} },
9928 /* Adobe RGB (1998) */
9929 /*gamma:*/ { 1/(2+51./256),
9930 /*red: */ { 0.576669042910131, 0.297344975250536, 0.027031361386412 },
9931 /*green:*/ { 0.185558237906546, 0.627363566255466, 0.070688852535827 },
9932 /*blue: */ { 0.188228646234995, 0.075291458493998, 0.991337536837639} },
9933 /* Adobe Wide Gamut RGB */
9934 /*gamma:*/ { 1/(2+51./256),
9935 /*red: */ { 0.716500716779386, 0.258728243040113, 0.000000000000000 },
9936 /*green:*/ { 0.101020574397477, 0.724682314948566, 0.051211818965388 },
9937 /*blue: */ { 0.146774385252705, 0.016589442011321, 0.773892783545073} },
9942 * This attempts to trap signals and escape without crashing. It needs a
9943 * context pointer so that it can throw an exception (call longjmp) to recover
9944 * from the condition; this is handled by making the png_modifier used by 'main'
9945 * into a global variable.
9947 static png_modifier pm;
9949 static void signal_handler(int signum)
9955 pos = safecat(msg, sizeof msg, pos, "caught signal: ");
9960 pos = safecat(msg, sizeof msg, pos, "abort");
9964 pos = safecat(msg, sizeof msg, pos, "floating point exception");
9968 pos = safecat(msg, sizeof msg, pos, "illegal instruction");
9972 pos = safecat(msg, sizeof msg, pos, "interrupt");
9976 pos = safecat(msg, sizeof msg, pos, "invalid memory access");
9980 pos = safecat(msg, sizeof msg, pos, "termination request");
9984 pos = safecat(msg, sizeof msg, pos, "unknown ");
9985 pos = safecatn(msg, sizeof msg, pos, signum);
9989 store_log(&pm.this, NULL/*png_structp*/, msg, 1/*error*/);
9991 /* And finally throw an exception so we can keep going, unless this is
9992 * SIGTERM in which case stop now.
9994 if (signum != SIGTERM)
9996 struct exception_context *the_exception_context =
9997 &pm.this.exception_context;
10007 int main(int argc, char **argv)
10009 volatile int summary = 1; /* Print the error summary at the end */
10010 volatile int memstats = 0; /* Print memory statistics at the end */
10012 /* Create the given output file on success: */
10013 PNG_CONST char *volatile touch = NULL;
10015 /* This is an array of standard gamma values (believe it or not I've seen
10016 * every one of these mentioned somewhere.)
10018 * In the following list the most useful values are first!
10021 gammas[]={2.2, 1.0, 2.2/1.45, 1.8, 1.5, 2.4, 2.5, 2.62, 2.9};
10023 /* This records the command and arguments: */
10025 char command[1024];
10027 anon_context(&pm.this);
10029 /* Add appropriate signal handlers, just the ANSI specified ones: */
10030 signal(SIGABRT, signal_handler);
10031 signal(SIGFPE, signal_handler);
10032 signal(SIGILL, signal_handler);
10033 signal(SIGINT, signal_handler);
10034 signal(SIGSEGV, signal_handler);
10035 signal(SIGTERM, signal_handler);
10037 #ifdef HAVE_FEENABLEEXCEPT
10038 /* Only required to enable FP exceptions on platforms where they start off
10039 * disabled; this is not necessary but if it is not done pngvalid will likely
10040 * end up ignoring FP conditions that other platforms fault.
10042 feenableexcept(FE_DIVBYZERO | FE_INVALID | FE_OVERFLOW);
10045 modifier_init(&pm);
10047 /* Preallocate the image buffer, because we know how big it needs to be,
10048 * note that, for testing purposes, it is deliberately mis-aligned by tag
10049 * bytes either side. All rows have an additional five bytes of padding for
10050 * overwrite checking.
10052 store_ensure_image(&pm.this, NULL, 2, TRANSFORM_ROWMAX, TRANSFORM_HEIGHTMAX);
10054 /* Don't give argv[0], it's normally some horrible libtool string: */
10055 cp = safecat(command, sizeof command, cp, "pngvalid");
10057 /* Default to error on warning: */
10058 pm.this.treat_warnings_as_errors = 1;
10060 /* Default assume_16_bit_calculations appropriately; this tells the checking
10061 * code that 16-bit arithmetic is used for 8-bit samples when it would make a
10064 pm.assume_16_bit_calculations = PNG_LIBPNG_VER >= 10700;
10066 /* Currently 16 bit expansion happens at the end of the pipeline, so the
10067 * calculations are done in the input bit depth not the output.
10071 pm.calculations_use_input_precision = 1U;
10073 /* Store the test gammas */
10074 pm.gammas = gammas;
10075 pm.ngammas = (sizeof gammas) / (sizeof gammas[0]);
10076 pm.ngamma_tests = 0; /* default to off */
10078 /* And the test encodings */
10079 pm.encodings = test_encodings;
10080 pm.nencodings = (sizeof test_encodings) / (sizeof test_encodings[0]);
10082 pm.sbitlow = 8U; /* because libpng doesn't do sBIT below 8! */
10084 /* The following allows results to pass if they correspond to anything in the
10085 * transformed range [input-.5,input+.5]; this is is required because of the
10086 * way libpng treates the 16_TO_8 flag when building the gamma tables in
10087 * releases up to 1.6.0.
10089 * TODO: review this
10091 pm.use_input_precision_16to8 = 1U;
10092 pm.use_input_precision_sbit = 1U; /* because libpng now rounds sBIT */
10094 /* Some default values (set the behavior for 'make check' here).
10095 * These values simply control the maximum error permitted in the gamma
10096 * transformations. The practial limits for human perception are described
10097 * below (the setting for maxpc16), however for 8 bit encodings it isn't
10098 * possible to meet the accepted capabilities of human vision - i.e. 8 bit
10099 * images can never be good enough, regardless of encoding.
10101 pm.maxout8 = .1; /* Arithmetic error in *encoded* value */
10102 pm.maxabs8 = .00005; /* 1/20000 */
10103 pm.maxcalc8 = 1./255; /* +/-1 in 8 bits for compose errors */
10104 pm.maxpc8 = .499; /* I.e., .499% fractional error */
10105 pm.maxout16 = .499; /* Error in *encoded* value */
10106 pm.maxabs16 = .00005;/* 1/20000 */
10107 pm.maxcalc16 =1./65535;/* +/-1 in 16 bits for compose errors */
10108 pm.maxcalcG = 1./((1<<PNG_MAX_GAMMA_8)-1);
10110 /* NOTE: this is a reasonable perceptual limit. We assume that humans can
10111 * perceive light level differences of 1% over a 100:1 range, so we need to
10112 * maintain 1 in 10000 accuracy (in linear light space), which is what the
10113 * following guarantees. It also allows significantly higher errors at
10114 * higher 16 bit values, which is important for performance. The actual
10115 * maximum 16 bit error is about +/-1.9 in the fixed point implementation but
10116 * this is only allowed for values >38149 by the following:
10118 pm.maxpc16 = .005; /* I.e., 1/200% - 1/20000 */
10120 /* Now parse the command line options. */
10121 while (--argc >= 1)
10123 int catmore = 0; /* Set if the argument has an argument. */
10125 /* Record each argument for posterity: */
10126 cp = safecat(command, sizeof command, cp, " ");
10127 cp = safecat(command, sizeof command, cp, *++argv);
10129 if (strcmp(*argv, "-v") == 0)
10130 pm.this.verbose = 1;
10132 else if (strcmp(*argv, "-l") == 0)
10135 else if (strcmp(*argv, "-q") == 0)
10136 summary = pm.this.verbose = pm.log = 0;
10138 else if (strcmp(*argv, "-w") == 0)
10139 pm.this.treat_warnings_as_errors = 0;
10141 else if (strcmp(*argv, "--speed") == 0)
10142 pm.this.speed = 1, pm.ngamma_tests = pm.ngammas, pm.test_standard = 0,
10145 else if (strcmp(*argv, "--memory") == 0)
10148 else if (strcmp(*argv, "--size") == 0)
10151 else if (strcmp(*argv, "--nosize") == 0)
10154 else if (strcmp(*argv, "--standard") == 0)
10155 pm.test_standard = 1;
10157 else if (strcmp(*argv, "--nostandard") == 0)
10158 pm.test_standard = 0;
10160 else if (strcmp(*argv, "--transform") == 0)
10161 pm.test_transform = 1;
10163 else if (strcmp(*argv, "--notransform") == 0)
10164 pm.test_transform = 0;
10166 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
10167 else if (strncmp(*argv, "--transform-disable=",
10168 sizeof "--transform-disable") == 0)
10170 pm.test_transform = 1;
10171 transform_disable(*argv + sizeof "--transform-disable");
10174 else if (strncmp(*argv, "--transform-enable=",
10175 sizeof "--transform-enable") == 0)
10177 pm.test_transform = 1;
10178 transform_enable(*argv + sizeof "--transform-enable");
10180 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
10182 else if (strcmp(*argv, "--gamma") == 0)
10184 /* Just do two gamma tests here (2.2 and linear) for speed: */
10185 pm.ngamma_tests = 2U;
10186 pm.test_gamma_threshold = 1;
10187 pm.test_gamma_transform = 1;
10188 pm.test_gamma_sbit = 1;
10189 pm.test_gamma_scale16 = 1;
10190 pm.test_gamma_background = 1;
10191 pm.test_gamma_alpha_mode = 1;
10194 else if (strcmp(*argv, "--nogamma") == 0)
10195 pm.ngamma_tests = 0;
10197 else if (strcmp(*argv, "--gamma-threshold") == 0)
10198 pm.ngamma_tests = 2U, pm.test_gamma_threshold = 1;
10200 else if (strcmp(*argv, "--nogamma-threshold") == 0)
10201 pm.test_gamma_threshold = 0;
10203 else if (strcmp(*argv, "--gamma-transform") == 0)
10204 pm.ngamma_tests = 2U, pm.test_gamma_transform = 1;
10206 else if (strcmp(*argv, "--nogamma-transform") == 0)
10207 pm.test_gamma_transform = 0;
10209 else if (strcmp(*argv, "--gamma-sbit") == 0)
10210 pm.ngamma_tests = 2U, pm.test_gamma_sbit = 1;
10212 else if (strcmp(*argv, "--nogamma-sbit") == 0)
10213 pm.test_gamma_sbit = 0;
10215 else if (strcmp(*argv, "--gamma-16-to-8") == 0)
10216 pm.ngamma_tests = 2U, pm.test_gamma_scale16 = 1;
10218 else if (strcmp(*argv, "--nogamma-16-to-8") == 0)
10219 pm.test_gamma_scale16 = 0;
10221 else if (strcmp(*argv, "--gamma-background") == 0)
10222 pm.ngamma_tests = 2U, pm.test_gamma_background = 1;
10224 else if (strcmp(*argv, "--nogamma-background") == 0)
10225 pm.test_gamma_background = 0;
10227 else if (strcmp(*argv, "--gamma-alpha-mode") == 0)
10228 pm.ngamma_tests = 2U, pm.test_gamma_alpha_mode = 1;
10230 else if (strcmp(*argv, "--nogamma-alpha-mode") == 0)
10231 pm.test_gamma_alpha_mode = 0;
10233 else if (strcmp(*argv, "--expand16") == 0)
10234 pm.test_gamma_expand16 = 1;
10236 else if (strcmp(*argv, "--noexpand16") == 0)
10237 pm.test_gamma_expand16 = 0;
10239 else if (strcmp(*argv, "--more-gammas") == 0)
10240 pm.ngamma_tests = 3U;
10242 else if (strcmp(*argv, "--all-gammas") == 0)
10243 pm.ngamma_tests = pm.ngammas;
10245 else if (strcmp(*argv, "--progressive-read") == 0)
10246 pm.this.progressive = 1;
10248 else if (strcmp(*argv, "--use-update-info") == 0)
10249 ++pm.use_update_info; /* Can call multiple times */
10251 else if (strcmp(*argv, "--interlace") == 0)
10253 # ifdef PNG_WRITE_INTERLACING_SUPPORTED
10254 pm.interlace_type = PNG_INTERLACE_ADAM7;
10256 fprintf(stderr, "pngvalid: no write interlace support\n");
10261 else if (strcmp(*argv, "--use-input-precision") == 0)
10262 pm.use_input_precision = 1U;
10264 else if (strcmp(*argv, "--use-calculation-precision") == 0)
10265 pm.use_input_precision = 0;
10267 else if (strcmp(*argv, "--calculations-use-input-precision") == 0)
10268 pm.calculations_use_input_precision = 1U;
10270 else if (strcmp(*argv, "--assume-16-bit-calculations") == 0)
10271 pm.assume_16_bit_calculations = 1U;
10273 else if (strcmp(*argv, "--calculations-follow-bit-depth") == 0)
10274 pm.calculations_use_input_precision =
10275 pm.assume_16_bit_calculations = 0;
10277 else if (strcmp(*argv, "--exhaustive") == 0)
10278 pm.test_exhaustive = 1;
10280 else if (argc > 1 && strcmp(*argv, "--sbitlow") == 0)
10281 --argc, pm.sbitlow = (png_byte)atoi(*++argv), catmore = 1;
10283 else if (argc > 1 && strcmp(*argv, "--touch") == 0)
10284 --argc, touch = *++argv, catmore = 1;
10286 else if (argc > 1 && strncmp(*argv, "--max", 5) == 0)
10290 if (strcmp(5+*argv, "abs8") == 0)
10291 pm.maxabs8 = atof(*++argv);
10293 else if (strcmp(5+*argv, "abs16") == 0)
10294 pm.maxabs16 = atof(*++argv);
10296 else if (strcmp(5+*argv, "calc8") == 0)
10297 pm.maxcalc8 = atof(*++argv);
10299 else if (strcmp(5+*argv, "calc16") == 0)
10300 pm.maxcalc16 = atof(*++argv);
10302 else if (strcmp(5+*argv, "out8") == 0)
10303 pm.maxout8 = atof(*++argv);
10305 else if (strcmp(5+*argv, "out16") == 0)
10306 pm.maxout16 = atof(*++argv);
10308 else if (strcmp(5+*argv, "pc8") == 0)
10309 pm.maxpc8 = atof(*++argv);
10311 else if (strcmp(5+*argv, "pc16") == 0)
10312 pm.maxpc16 = atof(*++argv);
10316 fprintf(stderr, "pngvalid: %s: unknown 'max' option\n", *argv);
10323 else if (strcmp(*argv, "--log8") == 0)
10324 --argc, pm.log8 = atof(*++argv), catmore = 1;
10326 else if (strcmp(*argv, "--log16") == 0)
10327 --argc, pm.log16 = atof(*++argv), catmore = 1;
10329 #ifdef PNG_SET_OPTION_SUPPORTED
10330 else if (strncmp(*argv, "--option=", 9) == 0)
10332 /* Syntax of the argument is <option>:{on|off} */
10333 const char *arg = 9+*argv;
10334 unsigned char option=0, setting=0;
10336 #ifdef PNG_ARM_NEON_API_SUPPORTED
10337 if (strncmp(arg, "arm-neon:", 9) == 0)
10338 option = PNG_ARM_NEON, arg += 9;
10342 #ifdef PNG_MAXIMUM_INFLATE_WINDOW
10343 if (strncmp(arg, "max-inflate-window:", 19) == 0)
10344 option = PNG_MAXIMUM_INFLATE_WINDOW, arg += 19;
10349 fprintf(stderr, "pngvalid: %s: %s: unknown option\n", *argv, arg);
10353 if (strcmp(arg, "off") == 0)
10354 setting = PNG_OPTION_OFF;
10356 else if (strcmp(arg, "on") == 0)
10357 setting = PNG_OPTION_ON;
10362 "pngvalid: %s: %s: unknown setting (use 'on' or 'off')\n",
10367 pm.this.options[pm.this.noptions].option = option;
10368 pm.this.options[pm.this.noptions++].setting = setting;
10370 #endif /* PNG_SET_OPTION_SUPPORTED */
10374 fprintf(stderr, "pngvalid: %s: unknown argument\n", *argv);
10378 if (catmore) /* consumed an extra *argv */
10380 cp = safecat(command, sizeof command, cp, " ");
10381 cp = safecat(command, sizeof command, cp, *argv);
10385 /* If pngvalid is run with no arguments default to a reasonable set of the
10388 if (pm.test_standard == 0 && pm.test_size == 0 && pm.test_transform == 0 &&
10389 pm.ngamma_tests == 0)
10391 /* Make this do all the tests done in the test shell scripts with the same
10392 * parameters, where possible. The limitation is that all the progressive
10393 * read and interlace stuff has to be done in separate runs, so only the
10394 * basic 'standard' and 'size' tests are done.
10396 pm.test_standard = 1;
10398 pm.test_transform = 1;
10399 pm.ngamma_tests = 2U;
10402 if (pm.ngamma_tests > 0 &&
10403 pm.test_gamma_threshold == 0 && pm.test_gamma_transform == 0 &&
10404 pm.test_gamma_sbit == 0 && pm.test_gamma_scale16 == 0 &&
10405 pm.test_gamma_background == 0 && pm.test_gamma_alpha_mode == 0)
10407 pm.test_gamma_threshold = 1;
10408 pm.test_gamma_transform = 1;
10409 pm.test_gamma_sbit = 1;
10410 pm.test_gamma_scale16 = 1;
10411 pm.test_gamma_background = 1;
10412 pm.test_gamma_alpha_mode = 1;
10415 else if (pm.ngamma_tests == 0)
10417 /* Nothing to test so turn everything off: */
10418 pm.test_gamma_threshold = 0;
10419 pm.test_gamma_transform = 0;
10420 pm.test_gamma_sbit = 0;
10421 pm.test_gamma_scale16 = 0;
10422 pm.test_gamma_background = 0;
10423 pm.test_gamma_alpha_mode = 0;
10428 /* Make useful base images */
10429 make_transform_images(&pm.this);
10431 /* Perform the standard and gamma tests. */
10432 if (pm.test_standard)
10434 perform_interlace_macro_validation();
10435 perform_formatting_test(&pm.this);
10436 # ifdef PNG_READ_SUPPORTED
10437 perform_standard_test(&pm);
10439 perform_error_test(&pm);
10442 /* Various oddly sized images: */
10445 make_size_images(&pm.this);
10446 # ifdef PNG_READ_SUPPORTED
10447 perform_size_test(&pm);
10451 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
10452 /* Combinatorial transforms: */
10453 if (pm.test_transform)
10454 perform_transform_test(&pm);
10455 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
10457 #ifdef PNG_READ_GAMMA_SUPPORTED
10458 if (pm.ngamma_tests > 0)
10459 perform_gamma_test(&pm, summary);
10465 fprintf(stderr, "pngvalid: test aborted (probably failed in cleanup)\n");
10466 if (!pm.this.verbose)
10468 if (pm.this.error[0] != 0)
10469 fprintf(stderr, "pngvalid: first error: %s\n", pm.this.error);
10471 fprintf(stderr, "pngvalid: run with -v to see what happened\n");
10478 printf("%s: %s (%s point arithmetic)\n",
10479 (pm.this.nerrors || (pm.this.treat_warnings_as_errors &&
10480 pm.this.nwarnings)) ? "FAIL" : "PASS",
10482 #if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || PNG_LIBPNG_VER < 10500
10492 printf("Allocated memory statistics (in bytes):\n"
10493 "\tread %lu maximum single, %lu peak, %lu total\n"
10494 "\twrite %lu maximum single, %lu peak, %lu total\n",
10495 (unsigned long)pm.this.read_memory_pool.max_max,
10496 (unsigned long)pm.this.read_memory_pool.max_limit,
10497 (unsigned long)pm.this.read_memory_pool.max_total,
10498 (unsigned long)pm.this.write_memory_pool.max_max,
10499 (unsigned long)pm.this.write_memory_pool.max_limit,
10500 (unsigned long)pm.this.write_memory_pool.max_total);
10503 /* Do this here to provoke memory corruption errors in memory not directly
10504 * allocated by libpng - not a complete test, but better than nothing.
10506 store_delete(&pm.this);
10508 /* Error exit if there are any errors, and maybe if there are any
10511 if (pm.this.nerrors || (pm.this.treat_warnings_as_errors &&
10512 pm.this.nwarnings))
10514 if (!pm.this.verbose)
10515 fprintf(stderr, "pngvalid: %s\n", pm.this.error);
10517 fprintf(stderr, "pngvalid: %d errors, %d warnings\n", pm.this.nerrors,
10518 pm.this.nwarnings);
10523 /* Success case. */
10526 FILE *fsuccess = fopen(touch, "wt");
10528 if (fsuccess != NULL)
10531 fprintf(fsuccess, "PNG validation succeeded\n");
10533 error = ferror(fsuccess);
10535 if (fclose(fsuccess) || error)
10537 fprintf(stderr, "%s: write failed\n", touch);
10544 fprintf(stderr, "%s: open failed\n", touch);
10549 /* This is required because some very minimal configurations do not use it:
10554 #else /* write or low level APIs not supported */
10558 "pngvalid: no low level write support in libpng, all tests skipped\n");
10559 /* So the test is skipped: */