ApiDemo學習之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 用顏色填充圖形
			// Paint.Style.FILL_AND_STROKE 即繪製邊框 同時也填充內部
			// Paint.Style.STROKE 個人理解爲只繪製邊框

            mPaint = new Paint();
            mPaint.setAntiAlias(true);//抗鋸齒，平滑效果
            mPaint.setStrokeWidth(6);//設置邊框像素
            mPaint.setTextSize(16);//設置字體大小號
            mPaint.setTextAlign(Paint.Align.RIGHT);//設置字體的對齊方式
            
            mPath = new Path();//基本圖形類
        }
        
        private void drawScene(Canvas canvas) {
            canvas.clipRect(0, 0, 100, 100);//設定圖形範圍
            
            canvas.drawColor(Color.WHITE);//圖形底色爲白色
            
            mPaint.setColor(Color.RED);
            canvas.drawLine(0, 0, 100, 100, mPaint);//繪製紅線
            
            mPaint.setColor(Color.GREEN);
            canvas.drawCircle(30, 70, 30, mPaint);//繪製（30.70）爲圓心，半徑爲30的圓
            
            mPaint.setColor(Color.BLUE);
            canvas.drawText("Clipping", 100, 30, mPaint);//在（100,30）座標，開始寫字~右對齊
        }
        
        @Override protected void onDraw(Canvas canvas) {
            canvas.drawColor(Color.GRAY);            

            canvas.save();
            //translate(x,y)其實參數的意思是原來的原點分別在x軸和y軸偏移多遠的距離，然後以偏移後的位置作爲座標原點。
            //也就是說原來在（100,100）,然後translate（1，1）新的座標原點在（101,101）而不是（1,1） 
            canvas.translate(10, 10);
            drawScene(canvas);
            canvas.restore();//恢復到原來的canvas，沒經過原點移動
            
            canvas.save();
            canvas.translate(160, 10);
            canvas.clipRect(10, 10, 90, 90);//繪製一個範圍
            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 可以看出來 每次繪圖都是有兩次的剪切方法的