大家好 小弟目前写了一只APP 其中有个功能是 当手势在萤幕上 由右往左 划 canvas就绘画横线 反之 由左往右划 canvas就绘画直线 程式流程大概为 用XY座标判断使用者是左划还右划 判断完後先清除surfaceview 在画线 可是执行後 canvas画了第一条线後 再画第二条 第一条不会被清除 还是会在 执行画面如下图 先画第一条 http://ppt.cc/yr_R 在画另一条(原本的横线还是在，没有被清除) http://ppt.cc/X6RJ 部分主要程式码如下 //判断手势 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { // TODO Auto-generated method stub Log.i("Fling", "Fling Happened!"); draw(drawAction.clear); if (e1.getX() - e2.getX() > 150) { draw(drawAction.draw_h); present_status.setText("横线"); } else if (e1.getX() - e2.getX() < -150) { draw(drawAction.draw_v); present_status.setText("直线"); } return true; } //判断绘图 @Override protected void onResume() { super.onResume(); } enum drawAction { draw_h, draw_v, clear, } void draw(drawAction action) { try { // 锁定 canvas = surfaceHolder.lockCanvas(null); synchronized (surfaceHolder) { //做不同的绘图 switch (action) { case draw_h: draw_H(canvas); break; case draw_v: draw_V(canvas); break; case clear: clear(canvas); break; } } } finally { if (canvas != null) { surfaceHolder.unlockCanvasAndPost(canvas); } } } //画水平线 void draw_H(Canvas canvas) { Paint p = new Paint(); p.setARGB(500, 0, 255, 0); canvas.drawLine(50,100,400,100, p); } //画垂直线 void draw_V(Canvas canvas) { Paint p = new Paint(); p.setARGB(500, 0, 255, 0); canvas.drawLine(100,50,100,400, p); } //清除 void clear(Canvas canvas) { Paint p = new Paint(); p.setARGB(255, 0, 0, 0); Rect rect = new Rect(0, 0, SurfaceView01.getWidth(), SurfaceView01.getHeight()); canvas.drawRect(rect, p); } 先谢谢各位大大帮忙了 --

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