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我正在尝试使用圆形倒置剪裁绘制蒙版位图。预期的效果应该看起来像太阳光线从圆的边缘向一个方向发光。掩蔽工作得很好，但剪掉内圈是行不通的。有什么我想念的吗？

这是 ImageView 的 onDraw 方法，带有一个额外的掩码位图。在 eclipse ADT 工具中预览视图时，使用此代码几乎可以正常工作（Xfermode 除外，它在预览中不受支持），但在设备上会忽略剪辑。 

@Override
protected void onDraw(Canvas canvas) {

    if (originalBounds == null) {
        originalBounds = new Rect();
        getDrawingRect(originalBounds);

        maskDrawable.setBounds(originalBounds);
        maskBitmap = drawableToBitmap(maskDrawable, getWidth(),
                getHeight(), Config.ARGB_8888);
        bitmap = drawableToBitmap(getDrawable(), getWidth(), getHeight(),
                Config.ARGB_8888);

    }

    if (clipPath == null && clipPathRadius != 0) {
        clipPath = new Path();
        clipPath.addCircle(originalBounds.exactCenterX(),
                originalBounds.exactCenterY(), clipPathRadius,
                Path.Direction.CCW);

    }

    canvas.saveLayer(originalBounds.left, originalBounds.top,
            originalBounds.right, originalBounds.bottom, null,
            Canvas.MATRIX_SAVE_FLAG | Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
                    | Canvas.FULL_COLOR_LAYER_SAVE_FLAG
                    | Canvas.CLIP_SAVE_FLAG
                    | Canvas.CLIP_TO_LAYER_SAVE_FLAG);

    if (clipPath != null) {
        canvas.clipPath(clipPath, Op.DIFFERENCE);
    }

    paint.setXfermode(null);
    canvas.drawBitmap(bitmap, null, originalBounds, paint);

    paint.setXfermode(xfermode);
    canvas.saveLayer(originalBounds.left, originalBounds.top,
            originalBounds.right, originalBounds.bottom, paint,
            Canvas.MATRIX_SAVE_FLAG | Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
                    | Canvas.FULL_COLOR_LAYER_SAVE_FLAG
                    | Canvas.CLIP_SAVE_FLAG
                    | Canvas.CLIP_TO_LAYER_SAVE_FLAG);

    paint.setXfermode(null);
    canvas.rotate(maskRotation, originalBounds.exactCenterX(),
            originalBounds.exactCenterY());
    if (clipPath != null) {
        canvas.clipPath(clipPath, Op.DIFFERENCE);
    }
    canvas.drawBitmap(maskBitmap, null, originalBounds, paint);
    canvas.rotate(0, originalBounds.exactCenterX(),
            originalBounds.exactCenterY());
    canvas.restore();
    canvas.restore();

}

这是预览显示的内容，可以清楚地看到中间的圆圈被剪掉了，但这在设备上并没有发生：

在此处输入图像描述

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