Android: Dragging Popup Window 可移动浮动框

 final View cv = new View(this);
    setContentView(cv);

    TextView tv = new TextView(this);
    tv.setBackgroundColor(0xffeeeeee);
    tv.setTextColor(0xff000000);
    tv.setTextSize(24);
    tv.setText("click me\nthen drag me");
    tv.setPadding(8, 8, 8, 8);
    mPopup = new PopupWindow(tv, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);

    OnTouchListener otl = new OnTouchListener() {
        private float mDx;
        private float mDy;

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            int action = event.getAction();
            if (action == MotionEvent.ACTION_DOWN) {
                mDx = mCurrentX - event.getRawX();
                mDy = mCurrentY - event.getRawY();
            } else
            if (action == MotionEvent.ACTION_MOVE) {
                mCurrentX = (int) (event.getRawX() + mDx);
                mCurrentY = (int) (event.getRawY() + mDy);
                mPopup.update(mCurrentX, mCurrentY, -1, -1);
            }
            return true;
        }
    };
    tv.setOnTouchListener(otl);

    mCurrentX = 20;
    mCurrentY = 50;
    cv.post(new Runnable() {
        @Override
        public void run() {
            mPopup.showAtLocation(cv, Gravity.NO_GRAVITY, mCurrentX, mCurrentY);
        }
    });