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