Add provider level support for PDF Thumbnails

Bug: 63586859
Test: N/A
Change-Id: I14b0dec18493478b3bd3585eab62aa64da909838

diff --git a/core/java/com/android/internal/content/FileSystemProvider.java b/core/java/com/android/internal/content/FileSystemProvider.java
index ebea1a4..04874bd 100644 (file)
--- a/core/java/com/android/internal/content/FileSystemProvider.java
+++ b/core/java/com/android/internal/content/FileSystemProvider.java
@@ -28,6 +28,7 @@ import android.database.MatrixCursor.RowBuilder;
 import android.graphics.Point;
 import android.net.Uri;
 import android.os.Binder;
+import android.os.Build;
 import android.os.CancellationSignal;
 import android.os.FileObserver;
 import android.os.FileUtils;
@@ -68,6 +69,8 @@ public abstract class FileSystemProvider extends DocumentsProvider {
 
     private Handler mHandler;
 
+    private static final String MIMETYPE_PDF = "application/pdf";
+
     protected abstract File getFileForDocId(String docId, boolean visible)
             throws FileNotFoundException;
 
@@ -387,6 +390,13 @@ public abstract class FileSystemProvider extends DocumentsProvider {
             String documentId, Point sizeHint, CancellationSignal signal)
             throws FileNotFoundException {
         final File file = getFileForDocId(documentId);
+        if (getTypeForFile(file).equals(MIMETYPE_PDF)) {
+            try {
+                return PdfUtils.openPdfThumbnail(file, sizeHint);
+            } catch (Exception e) {
+                Log.v(TAG, "Could not load PDF's thumbnail", e);
+            }
+        }
         return DocumentsContract.openImageThumbnail(file);
     }
 
@@ -416,7 +426,10 @@ public abstract class FileSystemProvider extends DocumentsProvider {
 
         final String mimeType = getTypeForFile(file);
         final String displayName = file.getName();
-        if (mimeType.startsWith("image/")) {
+        // As of right now, we aren't sure on the performance affect of loading all PDF Thumbnails
+        // Until a solution is found, it will be behind a debuggable flag.
+        if (mimeType.startsWith("image/")
+                || (mimeType.equals(MIMETYPE_PDF) && Build.IS_DEBUGGABLE)) {
             flags |= Document.FLAG_SUPPORTS_THUMBNAIL;
         }
 

diff --git a/core/java/com/android/internal/content/PdfUtils.java b/core/java/com/android/internal/content/PdfUtils.java
new file mode 100644 (file)
index 0000000..1716d42
--- /dev/null
+++ b/core/java/com/android/internal/content/PdfUtils.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.internal.content;
+
+import android.annotation.Nullable;
+import android.content.res.AssetFileDescriptor;
+import android.graphics.Bitmap;
+import android.graphics.Point;
+import android.graphics.Rect;
+import android.graphics.pdf.PdfRenderer;
+import android.os.AsyncTask;
+import android.os.ParcelFileDescriptor;
+
+import libcore.io.IoUtils;
+import libcore.io.Streams;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+/**
+ * Utils class for extracting PDF Thumbnails
+ */
+public final class PdfUtils {
+
+    private PdfUtils() {
+    }
+
+    /**
+     * Returns the front page of the pdf as a thumbnail
+     * @param file Given PDF File
+     * @param size Cropping of the front page.
+     * @return AssetFileDescriptor containing the thumbnail as a bitmap.
+     * @throws IOException if the file isn't a pdf or if the file doesn't exist.
+     */
+    public static @Nullable AssetFileDescriptor openPdfThumbnail(File file, Point size)
+            throws IOException {
+        // Create the bitmap of the PDF's first page
+        ParcelFileDescriptor pdfDescriptor =
+                ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);
+        PdfRenderer renderer = new PdfRenderer(pdfDescriptor);
+        PdfRenderer.Page frontPage = renderer.openPage(0);
+        Bitmap thumbnail = Bitmap.createBitmap(size.x, size.y,
+                Bitmap.Config.ARGB_8888);
+        frontPage.render(thumbnail, null, null, PdfRenderer.Page.RENDER_MODE_FOR_DISPLAY);
+
+        // Create an AssetFileDescriptor that contains the Bitmap's information
+        final ByteArrayOutputStream out = new ByteArrayOutputStream();
+        // Quality is an integer that determines how much compression is used.
+        // However, this integer is ignored when using the PNG format
+        int quality = 100;
+        // The use of Bitmap.CompressFormat.JPEG leads to a black PDF background on the thumbnail
+        thumbnail.compress(Bitmap.CompressFormat.PNG, quality, out);
+
+        final ByteArrayInputStream in = new ByteArrayInputStream(out.toByteArray());
+
+        final ParcelFileDescriptor[] fds = ParcelFileDescriptor.createReliablePipe();
+        new AsyncTask<Object, Object, Object>() {
+            @Override
+            protected Object doInBackground(Object... params) {
+                final FileOutputStream fos = new FileOutputStream(fds[1].getFileDescriptor());
+                try {
+                    Streams.copy(in, fos);
+                } catch (IOException e) {
+                    throw new RuntimeException(e);
+                }
+                IoUtils.closeQuietly(fds[1]);
+                try {
+                    pdfDescriptor.close();
+                } catch (IOException e) {
+                    throw new RuntimeException(e);
+                }
+                return null;
+            }
+        }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
+        pdfDescriptor.close();
+        return new AssetFileDescriptor(fds[0], 0, AssetFileDescriptor.UNKNOWN_LENGTH);
+    }
+
+}