Legacy Documentation: Version 5.1
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IDragHandler

interface in UnityEngine.EventSystems


Implements interfaces: IEventSystemHandler

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Description

Interface to implement if you wish to receive OnDrag callbacks.

#pragma strict
@RequireComponent(Image)
public class DragMe extends MonoBehaviour {
	public var dragOnSurfaces: boolean = true;
	private var m_DraggingIcon: GameObject;
	private var m_DraggingPlane: RectTransform;
	public function OnBeginDrag(eventData: PointerEventData) {
		var canvas: var = FindInParents.<Canvas>(gameObject);
		if (canvas == null)return ;
		// What we want to do is create an icon for this.
		m_DraggingIcon = new GameObject("icon");
		m_DraggingIcon.transform.SetParent(canvas.transform, false);
		m_DraggingIcon.transform.SetAsLastSibling();
		var image: var = m_DraggingIcon.AddComponent.<Image>();
		// We want it to be ignored by the event system.
		m_DraggingIcon.AddComponent.<IgnoreRaycast>();
		image.sprite = GetComponent.<Image>().sprite;
		image.SetNativeSize();
		if (dragOnSurfaces)
			m_DraggingPlane = transform as RectTransform;
		else
			m_DraggingPlane = canvas.transform as RectTransform;
		SetDraggedPosition(eventData);
	}
	public function OnDrag(data: PointerEventData) {
		if (m_DraggingIcon != null)
			SetDraggedPosition(data);
	}
	private function SetDraggedPosition(data: PointerEventData) {
		if (dragOnSurfaces && data.pointerEnter != null && data.pointerEnter.transform as RectTransform != null)
			m_DraggingPlane = data.pointerEnter.transform as RectTransform;
		var rt: var = m_DraggingIcon.GetComponent.<RectTransform>();
		var globalMousePos: Vector3;
		if (RectTransformUtility.PointInRectangleGlobalSpace(m_DraggingPlane, globalMousePos, data.position, data.pressEventCamera)) {
			rt.position = globalMousePos;
			rt.rotation = m_DraggingPlane.rotation;
		}
	}
	public function OnEndDrag(eventData: PointerEventData) {
		if (m_DraggingIcon != null)
			Destroy(m_DraggingIcon);
	}
	public static function FindInParents(go: GameObject) {
		if (go == null)return null;
		var comp: var = go.GetComponent.<T>();
		if (comp != null)return comp;
		var t: Transform = go.transform.parent;
		while ( t != null && comp == null ) {
			comp = t.gameObject.GetComponent.<T>();
			t = t.parent;
		}
		return comp;
	}
}

Public Functions

OnDragWhen draging is occuring this will be called every time the cursor is moved.