在Layers例程中 主要使用了
private static final int LAYER_FLAGS = //Canvas.MATRIX_SAVE_FLAG |
Canvas.CLIP_SAVE_FLAG |
//Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
Canvas.FULL_COLOR_LAYER_SAVE_FLAG |
Canvas.CLIP_TO_LAYER_SAVE_FLAG;

这个参数的不同组合 只是没有具体高清有啥具体的效果，只是懂得 最底层可以不显示

@Override protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.WHITE);

canvas.translate(10, 10);

canvas.saveLayerAlpha(0, 0, 200, 200, 0x66, LAYER_FLAGS);

mPaint.setColor(Color.RED);
canvas.drawCircle(75, 75, 75, mPaint);
mPaint.setColor(Color.BLUE);
canvas.drawCircle(125, 125, 75, mPaint);

canvas.restore();