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89 lines
2.8 KiB
89 lines
2.8 KiB
using System.Collections.Generic;
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using UnityEngine;
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using UnityEngine.EventSystems;
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using UnityEngine.UI;
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[RequireComponent(typeof(Image))]
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public class DragMe : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
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{
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public bool dragOnSurfaces = true;
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private Dictionary<int,GameObject> m_DraggingIcons = new Dictionary<int, GameObject>();
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private Dictionary<int, RectTransform> m_DraggingPlanes = new Dictionary<int, RectTransform>();
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public void OnBeginDrag(PointerEventData eventData)
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{
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var canvas = FindInParents<Canvas>(gameObject);
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if (canvas == null)
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return;
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// We have clicked something that can be dragged.
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// What we want to do is create an icon for this.
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m_DraggingIcons[eventData.pointerId] = new GameObject("icon");
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m_DraggingIcons[eventData.pointerId].transform.SetParent (canvas.transform, false);
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m_DraggingIcons[eventData.pointerId].transform.SetAsLastSibling();
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var image = m_DraggingIcons[eventData.pointerId].AddComponent<Image>();
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// The icon will be under the cursor.
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// We want it to be ignored by the event system.
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var group = m_DraggingIcons[eventData.pointerId].AddComponent<CanvasGroup>();
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group.blocksRaycasts = false;
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image.sprite = GetComponent<Image>().sprite;
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image.SetNativeSize();
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if (dragOnSurfaces)
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m_DraggingPlanes[eventData.pointerId] = transform as RectTransform;
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else
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m_DraggingPlanes[eventData.pointerId] = canvas.transform as RectTransform;
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SetDraggedPosition(eventData);
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}
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public void OnDrag(PointerEventData eventData)
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{
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if (m_DraggingIcons[eventData.pointerId] != null)
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SetDraggedPosition(eventData);
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}
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private void SetDraggedPosition(PointerEventData eventData)
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{
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if (dragOnSurfaces && eventData.pointerEnter != null && eventData.pointerEnter.transform as RectTransform != null)
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m_DraggingPlanes[eventData.pointerId] = eventData.pointerEnter.transform as RectTransform;
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var rt = m_DraggingIcons[eventData.pointerId].GetComponent<RectTransform>();
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Vector3 globalMousePos;
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if (RectTransformUtility.ScreenPointToWorldPointInRectangle(m_DraggingPlanes[eventData.pointerId], eventData.position, eventData.pressEventCamera, out globalMousePos))
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{
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rt.position = globalMousePos;
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rt.rotation = m_DraggingPlanes[eventData.pointerId].rotation;
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}
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}
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public void OnEndDrag(PointerEventData eventData)
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{
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if (m_DraggingIcons[eventData.pointerId] != null)
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Destroy(m_DraggingIcons[eventData.pointerId]);
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m_DraggingIcons[eventData.pointerId] = null;
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}
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static public T FindInParents<T>(GameObject go) where T : Component
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{
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if (go == null) return null;
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var comp = go.GetComponent<T>();
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if (comp != null)
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return comp;
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var t = go.transform.parent;
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while (t != null && comp == null)
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{
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comp = t.gameObject.GetComponent<T>();
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t = t.parent;
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}
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return comp;
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}
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}
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