1.创建

 mViewDragHelper = ViewDragHelper.create(this,mViewDragHelperCallback);

2.拖动

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        mViewDragHelper.processTouchEvent(event);
        return true;
    }

    //1.拖动我们的子view
    private ViewDragHelper.Callback mViewDragHelperCallback = new ViewDragHelper.Callback() {
        @Override
        public boolean tryCaptureView(@NonNull View child, int pointerId) {
            //在这里可以指定子 view 是否可以拖动
            return true;
        }

        @Override
        public int clampViewPositionVertical(@NonNull View child, int top, int dy) {
            //垂直拖动的位置
            return top;
        }
 
        @Override
        public int clampViewPositionHorizontal(@NonNull View child, int left, int dx) {
            return left;//水平拖动
        }
    };