Canvas中的java.lang.UnsupportedOperationException

Question

I used a custom ImageView in my app. But it shows

java.lang.UnsupportedOperationException

in the code canvas.clipPath(clipPath) .

I don't know why I got this error. It works perfectly on some phones.

public class Gma_CustomImage2 extends ImageView {

    public static float radius = 10.0f;  

    public Gma_CustomImage2(Context context) {
        super(context);
    }

    public Gma_CustomImage2(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public Gma_CustomImage2(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        Path clipPath = new Path();
        RectF rect = new RectF(0, 0, this.getWidth(), this.getHeight()+13.0f);
        clipPath.addRoundRect(rect, radius, radius, Path.Direction.CW);
        canvas.clipPath(clipPath);
        super.onDraw(canvas);
    }
}

LogCat

08-08 12:04:47.963: E/AndroidRuntime(5710): FATAL EXCEPTION: main
08-08 12:04:47.963: E/AndroidRuntime(5710): java.lang.UnsupportedOperationException
08-08 12:04:47.963: E/AndroidRuntime(5710):     at    android.view.GLES20Canvas.clipPath(GLES20Canvas.java:408)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at com.example.meetap.Gma_CustomImage2.onDraw(Gma_CustomImage2.java:34)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.draw(View.java:10982)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.getDisplayList(View.java:10421)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:2597)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.getDisplayList(View.java:10384)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:2597)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.getDisplayList(View.java:10384)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:2597)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.getDisplayList(View.java:10384)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.drawChild(ViewGroup.java:2850)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2489)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.draw(View.java:10985)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.widget.FrameLayout.draw(FrameLayout.java:450)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.widget.ScrollView.draw(ScrollView.java:1524)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.getHardwareLayer(View.java:10220)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.drawChild(ViewGroup.java:2863)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2489)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at com.example.meetap.Gma_CustomViewBehind.dispatchDraw(Gma_CustomViewBehind.java:121)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.getDisplayList(View.java:10419)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.drawChild(ViewGroup.java:2850)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2489)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.getDisplayList(View.java:10419)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:2597)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.getDisplayList(View.java:10384)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:2597)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.getDisplayList(View.java:10384)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewGroup.dispatchGetDisplayList(ViewGroup.java:2597)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.View.getDisplayList(View.java:10384)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.HardwareRenderer$GlRenderer.draw(HardwareRenderer.java:842)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewRootImpl.draw(ViewRootImpl.java:1935)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1659)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2467)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.os.Looper.loop(Looper.java:137)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at android.app.ActivityThread.main(ActivityThread.java:4424)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at java.lang.reflect.Method.invokeNative(Native Method)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at java.lang.reflect.Method.invoke(Method.java:511)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
08-08 12:04:47.963: E/AndroidRuntime(5710):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

use this code:

if (Build.VERSION.SDK_INT > Build.VERSION_CODES.HONEYCOMB) {
   Gma_CustomImage.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
}

Answer 2

You must turn hardware acceleration off for clipPath() to work. More specifically, call

this.setLayerType(View.LAYER_TYPE_SOFTWARE, null) (as specified by the page mentioned here ). Basically you want to leave hardware acceleration on for the rest of your application but turn it off specifically in this situation where clipPath() is not supported with it on.

Also look at the table on the page.

Answer 3

Work around Canvas.clipPath() that is not supported in android any more -

clipPath is only supported with hardware acceleration turned off.

The main idea here is to disable hardware acceleration in the part of the application where you need to use the unsupported methods. You can do it for a particular view, there's no need to turn it off completely for the whole application.