Unity UGUI event interface Overview

[Introduction] Interface

Namespace: using UnityEngine.EventSystems;

IPointerEnterHandler

This interface is implemented as follows:

void OnPointerEnter public (PointerEventData eventDataA) 
{ 
    // triggered when the mouse cursor into the subject 
}

IPointerExitHandler

This interface is implemented as follows:

void OnPointerExit public (PointerEventData eventDataA) 
{ 
    // triggered when the mouse cursor out of the subject 
}

IPointerDownHandler

This interface is implemented as follows:

void OnPointerDown public (PointerEventData eventDataA) 
{ 
    // A mouse click on the object, A target in response to this event, when the mouse 
}

IPointerUpHandler

This interface is implemented as follows:

void OnPointerUp public (PointerEventData eventData) 
{ 
    // A mouse click on the object, the response when you lift the mouse 
    // regardless of where the mouse lifted (ie, not the object A) 
    // will respond to this event in the A object 
    // Note: provided that a in response to this event through the object must respond to events OnPointerDown 
    Debug.Log ( "OnPointerUp" + name); 
}

IPointerClickHandler

This interface is implemented as follows:

void OnPointerClick public (PointerEventData eventDataA) 
{ 
    // A mouse click on the object, A in response to this event the object is lifted mouse 
    // NOTE: When lifting the mouse to be pressed and at the same object 
}

IDragHandler

This interface is implemented as follows:

void ondrag public (PointerEventData eventDataA) 
{ 
    // when the mouse is pressed on the object A and the object A in response to this event once per frame when the dragging 
    // NOTE: If you do not implement this interface, the four interfaces will not trigger the latter method 
    Debug.Log ( "ondrag" + name); 

    IF (Input.GetMouseButton (0)) 
    { 
        // drag moving pictures 
        SetDraggedPosition (eventDataA); 
    } 
} 
Private void SetDraggedPosition (PointerEventData eventDataA) 
{ 
    var gameObject.GetComponent RT = <RectTransform > (); 
    Vector3 globalMousePos; 
     IF (RectTransformUtility.ScreenPointToWorldPointInRectangle (RT, eventData.position, eventData.pressEventCamera, globalMousePos OUT)) 
    { 
        rt.position globalMousePos =; 
    } 
}

IInitializePotentialDragHandler

This interface is implemented as follows:

void OnInitializePotentialDrag public (PointerEventData eventDataA) 
{ 
    // when the mouse is pressed when the object A has not yet begun drag objects respond to this event A 
    // NOTE: This interface similar to interface events IPointerDownHandler event 
    execution order of both @: first execution IPointerDownHandler, then execute the interface event 
    Debug.Log ( "OnInitializePotentialDrag" + name); 
}

IBeginDragHandler

This interface is implemented as follows:

void OnBeginDrag public (PointerEventData eventDataA) 
{ 
    // when the mouse down and begins dragging the object A in response to this event object A 
    // response before this event response OnDrag after OnInitializePotentialDrag 
    Debug.Log ( "OnBeginDrag" + name); 
}

IEndDragHandler

This interface is implemented as follows:

void OnEndDrag public (PointerEventData eventDataA) 
{ 
    // when the mouse event in response to the object A is lifted 
    Debug.Log ( "OnEndDrag" + name); 
}

IDropHandler

This interface is implemented as follows:

void OnDrop public (PointerEventData eventDataA) 
{ 
    // A, B object must have achieved IDropHandler interface A and an interface implemented at least IDragHandler 
    @ A when the object starts from the mouse drag, the object B in response to this event when lifting the object B 
    // At this time, the acquired name is the name attribute of the object B 
    //eventData.pointerDrag represents initiated dragged objects (the GameObject) 
    Debug.Log (eventData.pointerDrag.name + "OnDrop to" + name); 
}