[ Android ] Canvas - 清除畫布的方法

// 清除畫面
   private void clearDraw() {
     Canvas canvas = holder.lockCanvas();
     canvas.drawColor(Color.TRANSPARENT);

     Paint p = new Paint();
     //清屏
     p.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
     canvas.drawPaint(p);

     holder.unlockCanvasAndPost(canvas);
   }

註：缺點用移動「 onTouchEvent 」畫布會狂閃的畫面