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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.

// There is no Javascript equivalent for this example. Please use the C# version.
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

[RequireComponent(typeof(Image))] public class DragMe : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler { public bool dragOnSurfaces = true;

private GameObject m_DraggingIcon; private RectTransform m_DraggingPlane;

public void OnBeginDrag(PointerEventData eventData) { var canvas = FindInParents<Canvas>(gameObject); if (canvas == null) return;

// We have clicked something that can be dragged. // 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 = m_DraggingIcon.AddComponent<Image>();

image.sprite = GetComponent<Image>().sprite; image.SetNativeSize();

if (dragOnSurfaces) m_DraggingPlane = transform as RectTransform; else m_DraggingPlane = canvas.transform as RectTransform;

SetDraggedPosition(eventData); }

public void OnDrag(PointerEventData data) { if (m_DraggingIcon != null) SetDraggedPosition(data); }

private void SetDraggedPosition(PointerEventData data) { if (dragOnSurfaces && data.pointerEnter != null && data.pointerEnter.transform as RectTransform != null) m_DraggingPlane = data.pointerEnter.transform as RectTransform;

var rt = m_DraggingIcon.GetComponent<RectTransform>(); Vector3 globalMousePos; if (RectTransformUtility.ScreenPointToWorldPointInRectangle(m_DraggingPlane, data.position, data.pressEventCamera, out globalMousePos)) { rt.position = globalMousePos; rt.rotation = m_DraggingPlane.rotation; } }

public void OnEndDrag(PointerEventData eventData) { if (m_DraggingIcon != null) Destroy(m_DraggingIcon); }

static public T FindInParents<T>(GameObject go) where T : Component { if (go == null) return null; var comp = go.GetComponent<T>();

if (comp != null) return comp;

Transform t = 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.