ApiDemo学习之Cilpping(剪切)

 

private static class SampleView extends View {
        private Paint mPaint;
        private Path mPath;

        public SampleView(Context context) {
            super(context);
            setFocusable(true);

			// Paint.Style.FILL 用颜色填充图形
			// Paint.Style.FILL_AND_STROKE 即绘制边框 同时也填充内部
			// Paint.Style.STROKE 个人理解为只绘制边框

            mPaint = new Paint();
            mPaint.setAntiAlias(true);//抗锯齿，平滑效果
            mPaint.setStrokeWidth(6);//设置边框像素
            mPaint.setTextSize(16);//设置字体大小号
            mPaint.setTextAlign(Paint.Align.RIGHT);//设置字体的对齐方式
            
            mPath = new Path();//基本图形类
        }
        
        private void drawScene(Canvas canvas) {
            canvas.clipRect(0, 0, 100, 100);//设定图形范围
            
            canvas.drawColor(Color.WHITE);//图形底色为白色
            
            mPaint.setColor(Color.RED);
            canvas.drawLine(0, 0, 100, 100, mPaint);//绘制红线
            
            mPaint.setColor(Color.GREEN);
            canvas.drawCircle(30, 70, 30, mPaint);//绘制（30.70）为圆心，半径为30的圆
            
            mPaint.setColor(Color.BLUE);
            canvas.drawText("Clipping", 100, 30, mPaint);//在（100,30）座标，开始写字~右对齐
        }
        
        @Override protected void onDraw(Canvas canvas) {
            canvas.drawColor(Color.GRAY);            

            canvas.save();
            //translate(x,y)其实参数的意思是原来的原点分别在x轴和y轴偏移多远的距离，然后以偏移后的位置作为座标原点。
            //也就是说原来在（100,100）,然后translate（1，1）新的座标原点在（101,101）而不是（1,1） 
            canvas.translate(10, 10);
            drawScene(canvas);
            canvas.restore();//恢复到原来的canvas，没经过原点移动
            
            canvas.save();
            canvas.translate(160, 10);
            canvas.clipRect(10, 10, 90, 90);//绘制一个范围
            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();
        }
    }

所以 可以看出来 每次绘图都是有两次的剪切方法的