</div>
</div>
- <p>Beginning in Android 3.0 (API level 11), the Android 2D rendering pipeline is designed to
- better support hardware acceleration. Hardware acceleration carries out all drawing operations
- that are performed on a {@link android.view.View}'s canvas using the GPU. Because of the
- increased resources required to enable hardware acceleration, your app will consume more RAM.</p>
-
- <p>The easiest way to enable hardware acceleration is to turn it on
- globally for your entire application. If your application uses only standard views and {@link
- android.graphics.drawable.Drawable}s, turning it on globally should not cause any adverse
- drawing effects. However, because hardware acceleration is not supported for all of the 2D drawing
- operations, turning it on might affect some of your applications that use custom views or drawing
- calls. Problems usually manifest themselves as invisible elements, exceptions, or wrongly
- rendered pixels. To remedy this, Android gives you the option to enable or disable hardware
- acceleration at the following levels:</p>
-
- <ul>
- <li>Application</li>
-
- <li>Activity</li>
-
- <li>Window</li>
-
- <li>View</li>
- </ul>
-
- <p>If your application performs custom drawing, test your application on actual hardware
-devices with hardware acceleration turned on to find any problems. The <a
-href="#drawing-support">Unsupported drawing operations</a> section describes known issues with
-drawing operations that cannot be hardware accelerated and how to work around them.</p>
-
+ <p>Beginning in Android 3.0 (API level 11), the Android 2D rendering pipeline supports hardware
+ acceleration, meaning that all drawing operations that are performed on a {@link
+ android.view.View}'s canvas use the GPU. Because of the increased resources required to enable
+ hardware acceleration, your app will consume more RAM.</p>
+
+ <p>Hardware acceleration is enabled by default if your Target API level is >=14, but can also
+ be explicitly enabled. If your application uses only standard views and {@link
+ android.graphics.drawable.Drawable}s, turning it on globally should not cause any adverse drawing
+ effects. However, because hardware acceleration is not supported for all of the 2D drawing
+ operations, turning it on might affect some of your custom views or drawing calls. Problems
+ usually manifest themselves as invisible elements, exceptions, or wrongly rendered pixels. To
+ remedy this, Android gives you the option to enable or disable hardware acceleration at multiple
+ levels. See <a href="#controlling">Controlling Hardware Acceleration</a>.</p>
+
+ <p>If your application performs custom drawing, test your application on actual hardware devices
+ with hardware acceleration turned on to find any problems. The <a
+ href="#drawing-support">Unsupported drawing operations</a> section describes known issues with
+ hardware acceleration and how to work around them.</p>
<h2 id="controlling">Controlling Hardware Acceleration</h2>
<p>You can control hardware acceleration at the following levels:</p>
</pre>
<h4>Activity level</h4>
- <p>If your application does not behave properly with hardware acceleration turned on globally,
- you can control it for individual activities as well. To enable or disable hardware acceleration
- at the activity level, you can use the <code>android:hardwareAccelerated</code>
-
attribute for the <a href="{@docRoot}guide/topics/manifest/activity-element.html">
- <code><activity></code></a> element. The following example enables hardware acceleration
-for the entire application but disables it for one activity:</p>
+ <p>If your application does not behave properly with hardware acceleration turned on globally, you
+ can control it for individual activities as well. To enable or disable hardware acceleration at
+ the activity level, you can use the <code>android:hardwareAccelerated</code> attribute for
+ the <a href="{@docRoot}guide/topics/manifest/activity-element.html">
+ <code><activity></code></a> element. The following example enables hardware acceleration for
+ the entire application but disables it for one activity:</p>
<pre>
<application android:hardwareAccelerated="true">
<p>With this model, you cannot rely on a view intersecting the dirty region to have its {@link
android.view.View#draw draw()} method executed. To ensure that the Android system records a
view’s display list, you must call {@link android.view.View#invalidate invalidate()}. Forgetting
- to do so causes a view to look the same even after changing it, which is an easier bug to find if
- it happens.</p>
+ to do so causes a view to look the same even after it has been changed.</p>
<p>Using display lists also benefits animation performance because setting specific properties,
such as alpha or rotation, does not require invalidating the targeted view (it is done
<p>The following table describes the support level of various operations across API levels:</p>
<style type="text/css">
- .tblGenFixed,.tblGeneric{font-size:15px}.tblGenFixed td {padding:0 3px;letter-spacing:0;word-spacing:0;background-color:#fff;z-index:1;border-top:0px none;border-left:0px none;border-bottom:1px solid #CCC;border-right:1px solid #CCC;} .dn {display:none} .tblGenFixed td.s0 {background-color:white;border-top:1px solid #CCC;border-left:1px solid #CCC;} .tblGenFixed td.s2 {background-color:#d9d9d9;color:#000000;text-align:center;} .tblGenFixed td.s1 {background-color:#434343;color:#ffffff;text-align:center;border-top:1px solid #CCC;} .tblGenFixed td.s9 {background-color:;color:#6aa84f;text-align:center;} .tblGenFixed td.s12 {background-color:white;color:#6aa84f;text-align:center;} .tblGenFixed td.s13 {background-color:#d9d9d9;color:#6aa84f;text-align:center;} .tblGenFixed td.s7 {background-color:#d9d9d9;color:#980000;text-align:center;} .tblGenFixed td.s8 {background-color:;color:#980000;text-align:center;} .tblGenFixed td.s5 {background-color:#434343;color:#ffffff;text-align:left;border-left:1px solid #CCC;} .tblGenFixed td.s6 {background-color:;font-family:courier new,monospace;color:;text-align:right;border-left:1px solid #CCC;} .tblGenFixed td.s10 {background-color:white;font-family:courier new,monospace;color:#000000;text-align:right;border-left:1px solid #CCC;} .tblGenFixed td.s3 {background-color:white;color:#000000;text-align:center;} .tblGenFixed td.s11 {background-color:white;color:#980000;text-align:center;} .tblGenFixed td.s4 {background-color:#d9d9d9;color:#000000;text-align:center;}
+ .tblGenFixed, .tblGeneric{font-size:15px}.tblGenFixed td {padding:0 3px;letter-spacing:0;word-spacing:0;background-color:#fff;z-index:1;border-top:0px none;border-left:0px none;border-bottom:1px solid #CCC;border-right:1px solid #CCC;} .dn {display:none} .tblGenFixed td.s0 {background-color:white;border-top:1px solid #CCC;border-left:1px solid #CCC;} .tblGenFixed td.s1 {background-color:#434343;color:#ffffff;text-align:center;border-top:1px solid #CCC;} .tblGenFixed td.s2 {background-color:#d9d9d9;color:#000000;text-align:center;} .tblGenFixed td.s3 {background-color:white;color:#000000;text-align:center;} .tblGenFixed td.s5 {background-color:#434343;color:#ffffff;text-align:left;border-left:1px solid #CCC;} .tblGenFixed td.s10 {background-color:white;font-family:courier new,monospace;color:#000000;text-align:right;border-left:1px solid #CCC;} .tblGenFixed td.g_pos {background-color:#d9d9d9;color:#6aa84f;text-align:center;} .tblGenFixed td.g_neg {background-color:#d9d9d9;color:#980000;text-align:center;} .tblGenFixed td.w_pos {background-color:white;color:#6aa84f;text-align:center;} .tblGenFixed td.w_neg {background-color:white;color:#980000;text-align:center;}
</style>
<table border="0" cellpadding="0" cellspacing="0" class="tblGenFixed" id="tblMain">
<tbody>
<td style="display:none;"></td>
<td class="s2">< 16</td>
<td class="s3">16</td>
- <td class="s4">17</td>
+ <td class="s2">17</td>
<td class="s3">18</td>
</tr>
<tr>
<td colspan="5" class="s5">Canvas</td>
</tr>
<tr>
- <td class="s6">clipPath()</td>
- <td class="s7">✗</td>
- <td class="s8">✗</td>
- <td class="s7">✗</td>
- <td class="s9">✓</td>
+ <td class="s10">drawBitmapMesh() (colors array)</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s10">clipRegion()</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
+ <td class="s10">drawPicture()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
- <td class="s10">clipRect(Region.Op.XOR)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
+ <td class="s10">drawPosText()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
+ <td class="g_pos">✓</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s10">clipRect(Region.Op.Difference)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
+ <td class="s10">drawTextOnPath()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
+ <td class="g_pos">✓</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s10">clipRect(Region.Op.ReverseDifference)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
+ <td class="s10">drawVertices()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
- <td class="s10">drawBitmapMesh() (colors array)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
+ <td class="s10">setDrawFilter()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
+ <td class="g_pos">✓</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s10">drawPicture()</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="s10">clipPath()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s10">drawPosText()</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
- <td class="s13">✓</td>
- <td class="s12">✓</td>
+ <td class="s10">clipRegion()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s10">drawTextOnPath()</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
- <td class="s13">✓</td>
- <td class="s12">✓</td>
+ <td class="s10">clipRect(Region.Op.XOR)</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s10">drawVertices()</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="s10">clipRect(Region.Op.Difference)</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s10">setDrawFilter()</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
- <td class="s13">✓</td>
- <td class="s12">✓</td>
+ <td class="s10">clipRect(Region.Op.ReverseDifference)</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
+ </tr>
+ <tr>
+ <td class="s10">clipRect() with rotation/perspective</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
<td colspan="5" class="s5">Paint</td>
</tr>
<tr>
- <td class="s6">setAntiAlias() (for text)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
+ <td class="s10">setAntiAlias() (for text)</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s6">setAntiAlias() (for lines)</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
- <td class="s13">✓</td>
- <td class="s12">✓</td>
+ <td class="s10">setAntiAlias() (for lines)</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
+ <td class="g_pos">✓</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s6">setFilterBitmap()</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s13">✓</td>
- <td class="s12">✓</td>
+ <td class="s10">setFilterBitmap()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_pos">✓</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
- <td class="s6">setLinearText()</td>
- <td class="s7">✗</td>
- <td class="s8">✗</td>
- <td class="s7">✗</td>
- <td class="s8">✗</td>
+ <td class="s10">setLinearText()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">setMaskFilter()</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">setPathEffect() (for lines)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">setRasterizer()</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">setShadowLayer() (other than text)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">setStrokeCap() (for lines)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s12">✓</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
</tr>
<tr>
<td class="s10">setStrokeCap() (for points)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">setSubpixelText()</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td colspan="5" class="s5">Xfermode</td>
</tr>
<tr>
- <td class="s6">AvoidXfermode</td>
- <td class="s7">✗</td>
- <td class="s8">✗</td>
- <td class="s7">✗</td>
- <td class="s8">✗</td>
+ <td class="s10">AvoidXfermode</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">PixelXorXfermode</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">PorterDuff.Mode.DARKEN (framebuffer)</td>
- <td class="s7">✗</td>
- <td class="s8">✗</td>
- <td class="s7">✗</td>
- <td class="s8">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">PorterDuff.Mode.LIGHTEN (framebuffer)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">PorterDuff.Mode.OVERLAY (framebuffer)</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td colspan="5" class="s5">Shader</td>
</tr>
<tr>
<td class="s10">ComposeShader inside ComposeShader</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">Same type shaders inside ComposeShader</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
</tr>
<tr>
<td class="s10">Local matrix on ComposeShader</td>
- <td class="s7">✗</td>
- <td class="s11">✗</td>
- <td class="s7">✗</td>
- <td class="s11">✓</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
</tr>
</tbody>
</table>
- <p>If your application is affected by any of these missing features or limitations, you can turn
- off hardware acceleration for just the affected portion of your application by calling
- {@link android.view.View#setLayerType setLayerType(View.LAYER_TYPE_SOFTWARE, null)}. This way,
-you can still take advantage of hardware acceleratin everywhere else. See <a
-href="#controlling">Controlling Hardware Acceleration</a> for more information on how to enable and
-disable hardware acceleration at different levels in your application.
+ <h3 id="scaling">Canvas Scaling</h3>
+
+ <p>The hardware accelerated 2D rendering pipeline was built first to support unscaled drawing,
+ with some drawing operations degrading quality significantly at higher scale values. These
+ operations are implemented as textures drawn at scale 1.0, transformed by the GPU. In API level
+ <17, using these operations will result in scaling artifacts increasing with scale.</p>
+
+ The following table shows when implementation was changed to correctly handle large scales:
+ <table border="0" cellpadding="0" cellspacing="0" class="tblGenFixed" id="tblMain">
+ <tbody>
+ <tr class="rShim">
+ <td class="rShim" style="width:380px;"></td>
+ <td class="rShim" style="width:120px;"></td>
+ <td class="rShim" style="width:120px;"></td>
+ <td class="rShim" style="width:120px;"></td>
+ </tr>
+ <tr>
+ <td rowspan="2" class="s0"></td>
+ <td colspan="4" class="s1">API level</td>
+ </tr>
+ <tr>
+ <td style="display:none;"></td>
+ <td class="s2">< 17</td>
+ <td class="s3">17</td>
+ <td class="s2">18</td>
+ </tr>
+ <tr>
+ <td colspan="5" class="s5">Support for large scale factors</td>
+ </tr>
+ <tr>
+ <td class="s10">drawText()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_pos">✓</td>
+ </tr>
+ <tr>
+ <td class="s10">drawPosText()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ </tr>
+ <tr>
+ <td class="s10">drawTextOnPath()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ </tr>
+ <tr>
+ <td class="s10">Simple Shapes*</td>
+ <td class="g_neg">✗</td>
+ <td class="w_pos">✓</td>
+ <td class="g_pos">✓</td>
+ </tr>
+ <tr>
+ <td class="s10">Complex Shapes*</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ </tr>
+ <tr>
+ <td class="s10">drawPath()</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ </tr>
+ <tr>
+ <td class="s10">Shadow layer</td>
+ <td class="g_neg">✗</td>
+ <td class="w_neg">✗</td>
+ <td class="g_neg">✗</td>
+ </tr>
+ </tbody>
+ </table>
+ <p class="note"><strong>Note</strong>: 'Simple' shapes are <code>drawRect()</code>,
+ <code>drawCircle()</code>, <code>drawOval()</code>, <code>drawRoundRect()</code>, and
+ <code>drawArc()</code> (with useCenter=false) commands issued with a Paint that doesn't have a
+ PathEffect, and doesn't contain non-default joins (via <code>setStrokeJoin()</code> /
+ <code>setStrokeMiter()</code>). Other instances of those draw commands fall under 'Complex,' in
+ the above chart.</p>
+
+ <p>If your application is affected by any of these missing features or limitations, you can turn
+ off hardware acceleration for just the affected portion of your application by calling {@link
+ android.view.View#setLayerType setLayerType(View.LAYER_TYPE_SOFTWARE, null)}. This way, you can
+ still take advantage of hardware acceleration everywhere else. See <a
+ href="#controlling">Controlling Hardware Acceleration</a> for more information on how to enable
+ and disable hardware acceleration at different levels in your application.
<h2 id="layers">View Layers</h2>
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