OnTouchEvent偵測

OnTouchEvent偵測
透過下列程式，可偵測Touch的動作
MotionEvent.ACTION_DOWN：壓下時觸發
MotionEvent.ACTION_MOVE：移動時觸發
MotionEvent.ACTION_UP：離開時觸發
    public boolean onTouchEvent(MotionEvent event){
        switch(event.getAction()) {
        case MotionEvent.ACTION_DOWN :
            temp_x = (int) event.getX();
            temp_y = (int) event.getY();
            break;
        case MotionEvent.ACTION_MOVE :
            break;
        case MotionEvent.ACTION_UP :
            break;
        default :
            break;
        }
        return false; 
    }

* event.getPointerCount() get count number