android4.0 开启硬件加速后应用运行出错

Android4.0 开启硬件加速后部分应用运行出错。

出现异常：

12-20 15:18:19.543: E/AndroidRuntime(26301): FATAL EXCEPTION: main

12-20 15:18:19.543: E/AndroidRuntime(26301): java.lang.UnsupportedOperationException

12-20 15:18:19.543: E/AndroidRuntime(26301): at android.view.GLES20Canvas.clipPath(GLES20Canvas.java:429)

12-20 15:18:19.543: E/AndroidRuntime(26301): at cn.hpc.ui.MyView.drawArea(MyView.java:66)

关闭硬件加速则运行正常。

原因在这里

http://developer.android.com/guide/topics/graphics/hardware-accel.html

Hardware Acceleration

Beginning in Android 3.0 (API level 11), the Android 2D rendering pipeline is designed to better support hardware acceleration.

从Android
3.0（API Level 11）开始，Android的2D渲染管线可以更好的支持硬件加速。硬件加速使用GPU进行View上的绘制操作。

... ...

Unsupported Drawing Operations

不支持的绘图方法：

Canvas

clipPath()

clipRegion()

drawPicture()

, int, int, android.graphics.Path, float, float, android.graphics.Paint)]drawTextOnPath()

, int, float[], int, int[], int, short[], int, int, android.graphics.Paint)]drawVertices()

Paint

setLinearText()

setMaskFilter()

setRasterizer()

Xfermodes

AvoidXfermode

PixelXorXfermode

我的应用中，正好用到第一种 clipPath.所以运行出错。

问题找到，

解决方法：

有4种控件硬件加速的方法。

1 Application level

In
your Android manifest file, add the following attribute to the

<application>

tag
to enable hardware acceleration for your entire application:

在应用程序AndroidManifest.xml文件中，为application标签添加如下的属性即可为整个应用程序true开启、false关闭硬件加速

<application android:hardwareAccelerated="false" ...>

2 Activity level

在应用程序AndroidManifest.xml文件中，只需在activity元素中添加android:hardwareAccelerated属性即可。
例：在application级别开启硬件加速，但在activity上关闭硬件加速。

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

3 Window level

If you need even more fine-grained control, you can enable hardware acceleration for a given window with the following code:

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

Note: You currently cannot disable hardware acceleration at the window level.

4 View level

You can disable hardware acceleration for an individual view at runtime with the following code:

myView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

测试中第1, 2 中都无效，第3种只能开启硬件加速,而不能关闭硬件加速。

只有第4种适合。只对当前View关闭硬件加速。
优点：View中使用到上述硬件加速不支持的方法时，强制关闭硬件加速。其它地方，由系统决定是否硬件加速。