关于ontouchlistener的监听滑动问题

relativeLayout.setOnTouchListener(new OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            // TODO Auto-generated method stub
            int action = event.getAction();
            switch (action) {
            case MotionEvent.ACTION_DOWN:
                x=event.getX();
                y=event.getY();
                break;
            case MotionEvent.ACTION_MOVE:
                mx=event.getX();
                my=event.getY();
                rx=mx-x;
                ry=my-y;
                mParams.x =(int) rx;
                mParams.y =(int)ry;
                mWM.updateViewLayout(ivCursor, mParams);
                break;
            case MotionEvent.ACTION_UP:

                break;
            }
            return true;
        }
    });

    浮动框的代码

    mWM = (WindowManager) getBaseContext().getSystemService(Context.WINDOW_SERVICE);
ivCursor = new ImageView(getBaseContext());
ivCursor.setImageResource(R.drawable.ic_launcher);
mParams = new WindowManager.LayoutParams();// 对ivCursor对象的参数描述对象
mParams.height = WindowManager.LayoutParams.WRAP_CONTENT;// 宽度自适应
mParams.width = WindowManager.LayoutParams.WRAP_CONTENT;// 高度自适应
mParams.flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;// 设置成不能获取焦点
mParams.type = LayoutParams.TYPE_PHONE;
// 设置图片格式，效果为背景透明
mParams.format = PixelFormat.RGBA_8888;
mParams.gravity = Gravity.CENTER_HORIZONTAL | Gravity.CENTER_VERTICAL;

mParams.x = 0;
mParams.y = 0;
mWM.addView(ivCursor, mParams);

当我手指滑动的时候 浮动框是跟着动的 松开后 再去滑动 浮空框就又从原点开始滑动了 有什么办法能让浮动框不从原点开始 就从停止的地方开始滑动啊