@Override
                public void down(MotionEvent event) {
                    touchDownY = getDialogImpl().boxBkg.getY();
                    log("#TouchDown: " + touchDownY);
                }
@author: Kongzue
@github: https://github.com/kongzue/
@homepage: http://kongzue.com/
@mail: myzcxhh@live.cn
@createTime: 2020/10/6 23:48
DialogX/src/main/java/com/kongzue/dialogx/dialogs/BottomMenu.java