android clipPath切割画布

转自：http://wallage.blog.163.com/blog/static/1738962420101012439991/）

 public class PictureTestActivity extends Activity {

        @Override
        public void onCreate(Bundle savedInstanceState){
            super.onCreate(savedInstanceState);
            setContentView(new SampleView(this));
        }
         private static class SampleView extends View {
             private Paint mPaint;
             private Path mPath;
             public SampleView(Context context) {
                 super(context);
                 setFocusable(true);

                 mPaint = new Paint();
                 mPaint.setAntiAlias(true);
                 mPaint.setStrokeWidth(6);
                 mPaint.setTextSize(16);
                 mPaint.setTextAlign(Paint.Align.RIGHT);

                 mPath = new Path();
             }

             private void drawScene(Canvas canvas) {
                 canvas.clipRect(0, 0, 100, 100);

                 canvas.drawColor(Color.WHITE);

                 mPaint.setColor(Color.RED);
                 canvas.drawLine(0, 0, 100, 100, mPaint);

                 mPaint.setColor(Color.GREEN);
                 canvas.drawCircle(30, 70, 30, mPaint);

                 mPaint.setColor(Color.BLUE);
                 canvas.drawText("Clipping", 100, 30, mPaint);
             }

             @Override
             protected void onDraw(Canvas canvas) {
                 canvas.drawColor(Color.GRAY);
                 canvas.save();
                 canvas.translate(10, 10);
                 drawScene(canvas);
                 canvas.restore();

                 canvas.save();
                 canvas.translate(160, 10);
                 canvas.clipRect(10, 10, 90, 90);
                 canvas.clipRect(30, 30, 70, 70, Region.Op.DIFFERENCE);
                 drawScene(canvas);
                 canvas.restore();

                 canvas.save();
                 canvas.translate(10, 160);
                 mPath.reset();
                 canvas.clipPath(mPath); // makes the clip empty
                 mPath.addCircle(50, 50, 50, Path.Direction.CCW);
                 canvas.clipPath(mPath, Region.Op.REPLACE);
                 drawScene(canvas);
                 canvas.restore();

                 canvas.save();
                 canvas.translate(160, 160);
                 canvas.clipRect(0, 0, 60, 60);
                 canvas.clipRect(40, 40, 100, 100, Region.Op.UNION);
                 drawScene(canvas);
                 canvas.restore();

                 canvas.save();
                 canvas.translate(10, 310);
                 canvas.clipRect(0, 0, 60, 60);
                 canvas.clipRect(40, 40, 100, 100, Region.Op.XOR);
                 drawScene(canvas);
                 canvas.restore();

                 canvas.save();
                 canvas.translate(160, 310);
                 canvas.clipRect(0, 0, 60, 60);
                 canvas.clipRect(40, 40, 100, 100, Region.Op.REVERSE_DIFFERENCE);
                 drawScene(canvas);
                 canvas.restore();
             }
         }
 }

效果如图：

canvas.clipRect(30, 30, 70, 70, Region.Op.XOR);最后一个参数有多个选择分别是：

            //DIFFERENCE是第一次不同于第二次的部分显示出来
            //REPLACE是显示第二次的
            //REVERSE_DIFFERENCE 是第二次不同于第一次的部分显示
            //INTERSECT交集显示
            //UNION全部显示
            //XOR补集 就是全集的减去交集生育部分显示