1 files changed, 88 insertions, 0 deletions
diff --git a/Assets/SampleUI/Scripts/DragMe.cs b/Assets/SampleUI/Scripts/DragMe.cs
new file mode 100755
index 0000000..f2b4cf7
--- /dev/null
+++ b/Assets/SampleUI/Scripts/DragMe.cs
@@ -0,0 +1,88 @@
+using System.Collections.Generic;
+using UnityEngine;
+using UnityEngine.EventSystems;
+using UnityEngine.UI;
+
+[RequireComponent(typeof(Image))]
+public class DragMe : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
+{
+	public bool dragOnSurfaces = true;
+	
+	private Dictionary<int,GameObject> m_DraggingIcons = new Dictionary<int, GameObject>();
+	private Dictionary<int, RectTransform> m_DraggingPlanes = new Dictionary<int, RectTransform>();
+
+	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_DraggingIcons[eventData.pointerId] = new GameObject("icon");
+
+		m_DraggingIcons[eventData.pointerId].transform.SetParent (canvas.transform, false);
+		m_DraggingIcons[eventData.pointerId].transform.SetAsLastSibling();
+		
+		var image = m_DraggingIcons[eventData.pointerId].AddComponent<Image>();
+		// The icon will be under the cursor.
+		// We want it to be ignored by the event system.
+		var group = m_DraggingIcons[eventData.pointerId].AddComponent<CanvasGroup>();
+		group.blocksRaycasts = false;
+
+		image.sprite = GetComponent<Image>().sprite;
+		image.SetNativeSize();
+		
+		if (dragOnSurfaces)
+			m_DraggingPlanes[eventData.pointerId] = transform as RectTransform;
+		else
+			m_DraggingPlanes[eventData.pointerId]  = canvas.transform as RectTransform;
+		
+		SetDraggedPosition(eventData);
+	}
+
+	public void OnDrag(PointerEventData eventData)
+	{
+		if (m_DraggingIcons[eventData.pointerId] != null)
+			SetDraggedPosition(eventData);
+	}
+
+	private void SetDraggedPosition(PointerEventData eventData)
+	{
+		if (dragOnSurfaces && eventData.pointerEnter != null && eventData.pointerEnter.transform as RectTransform != null)
+			m_DraggingPlanes[eventData.pointerId] = eventData.pointerEnter.transform as RectTransform;
+		
+		var rt = m_DraggingIcons[eventData.pointerId].GetComponent<RectTransform>();
+		Vector3 globalMousePos;
+		if (RectTransformUtility.ScreenPointToWorldPointInRectangle(m_DraggingPlanes[eventData.pointerId], eventData.position, eventData.pressEventCamera, out globalMousePos))
+		{
+			rt.position = globalMousePos;
+			rt.rotation = m_DraggingPlanes[eventData.pointerId].rotation;
+		}
+	}
+
+	public void OnEndDrag(PointerEventData eventData)
+	{
+		if (m_DraggingIcons[eventData.pointerId] != null)
+			Destroy(m_DraggingIcons[eventData.pointerId]);
+
+		m_DraggingIcons[eventData.pointerId] = null;
+	}
+
+	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;
+		
+		var t = go.transform.parent;
+		while (t != null && comp == null)
+		{
+			comp = t.gameObject.GetComponent<T>();
+			t = t.parent;
+		}
+		return comp;
+	}
+}