Unity Slider进度条鼠标拖动

Unity Slider进度条鼠标拖动
EventTrigger trigger = videoProgressSilder.GetComponent();
EventTrigger.Entry enterDown = new EventTrigger.Entry();
enterDown.eventID = EventTriggerType.PointerDown;
enterDown.callback.AddListener((eventData) => { OnPointerDown(); });
trigger.triggers.Add(enterDown);

    EventTrigger.Entry enterUp = new EventTrigger.Entry();
    enterUp.eventID = EventTriggerType.PointerUp;
    enterUp.callback.AddListener((eventDate)=>{ OnPointerUp(); });
    trigger.triggers.Add(enterUp);