彻底解决 Canvas 引起的 java.lang.unsupported operation exception

最近在做一个电子书项目，想要把开源的Shelves+iReader的翻页卷曲等弄到一起，在做卷曲效果时遇到以下问题：

 java.lang.unsupported operation exception, android.view.GLES20Canvas.clipPath(GLES20Canvas...

万能的谷哥告诉我，这是硬件加速的问题，可是我从来没开启过硬件加速啊，做了个测试，View层的硬件加速已经干掉了

，那硬件加速肯定来自于Canvas绘制层了，测试了下，果然是绘制层开启了硬件加速。

给一个链接，讲硬件加速讲的很清楚的文章：点击查看

综合看了之后解决了，即在AndroidManifest.xml application下设定：

< application android:label ="@string/application_name" android:hardwareAccelerated ="false" >

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关于 Hardware Acceleration

　 1、不同层级的加速：

Application

< applicationandroid:hardwareAccelerated ="true" ... >

Activity

< application android:hardwareAccelerated ="true" > < activity ... /> < activity android:hardwareAccelerated ="false" /> </ application >

Window

getWindow().setFlags( WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED, WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED);

View

myView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

2、如何判断是否开启了硬件加速

在绘制之前，你必须做该测试 Canvas.isHardwareAccelerated() 替代View.isHardwareAccelerated() 在必要时。

View.isHardwareAccelerated() ; // returns true if the View is attached to a hardware accelerated window. Canvas.isHardwareAccelerated(); // returns true if the Canvas is hardware accelerated

3、开启硬件加速之后，许多2D的绘制方法会抛出异常：

Canvas clipPath() clipRegion() drawPicture() drawTextOnPath() drawVertices() Paint setLinearText() setMaskFilter() setRasterizer() Xfermodes AvoidXfermode PixelXorXfermode

In addition, some operations behave differently with hardware acceleration enabled:

Canvas clipRect(): XOR, Difference and ReverseDifference clip modes are ignored. 3D transforms do not apply to the clip rectangle drawBitmapMesh(): colors array is ignored Paint setDither(): ignored setFilterBitmap(): filtering is always on setShadowLayer(): works with text only   PorterDuffXfermode PorterDuff.Mode.DARKEN will be equivalent to SRC_OVER when blending against the framebuffer. PorterDuff.Mode.LIGHTEN will be equivalent to SRC_OVER when blending against the framebuffer. PorterDuff.Mode.OVERLAY will be equivalent to SRC_OVER when blending against the framebuffer. ComposeShader ComposeShader can only contain shaders of different types (a BitmapShader and a LinearGradient for instance, but not two instances of BitmapShader ) ComposeShader cannot contain a ComposeShader