using System;
using UnityEditor.SceneManagement;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;
using UnityEngine.SceneManagement;
using UnityEditor.Experimental.SceneManagement;
 
namespace UnityEditor.UI
{
    /// <summary>
    /// This script adds the UI menu options to the Unity Editor.
    /// </summary>
 
    static internal class MenuOptions
    {
        private const string kUILayerName = "UI";
 
        private const string kStandardSpritePath       = "UI/Skin/UISprite.psd";
        private const string kBackgroundSpritePath     = "UI/Skin/Background.psd";
        private const string kInputFieldBackgroundPath = "UI/Skin/InputFieldBackground.psd";
        private const string kKnobPath                 = "UI/Skin/Knob.psd";
        private const string kCheckmarkPath            = "UI/Skin/Checkmark.psd";
        private const string kDropdownArrowPath        = "UI/Skin/DropdownArrow.psd";
        private const string kMaskPath                 = "UI/Skin/UIMask.psd";
 
        static private DefaultControls.Resources s_StandardResources;
 
        static private DefaultControls.Resources GetStandardResources()
        {
            if (s_StandardResources.standard == null)
            {
                s_StandardResources.standard = AssetDatabase.GetBuiltinExtraResource<Sprite>(kStandardSpritePath);
                s_StandardResources.background = AssetDatabase.GetBuiltinExtraResource<Sprite>(kBackgroundSpritePath);
                s_StandardResources.inputField = AssetDatabase.GetBuiltinExtraResource<Sprite>(kInputFieldBackgroundPath);
                s_StandardResources.knob = AssetDatabase.GetBuiltinExtraResource<Sprite>(kKnobPath);
                s_StandardResources.checkmark = AssetDatabase.GetBuiltinExtraResource<Sprite>(kCheckmarkPath);
                s_StandardResources.dropdown = AssetDatabase.GetBuiltinExtraResource<Sprite>(kDropdownArrowPath);
                s_StandardResources.mask = AssetDatabase.GetBuiltinExtraResource<Sprite>(kMaskPath);
            }
            return s_StandardResources;
        }
 
        private class DefaultEditorFactory : DefaultControls.IFactoryControls
        {
            public static DefaultEditorFactory Default = new DefaultEditorFactory();
 
            public GameObject CreateGameObject(string name, params Type[] components)
            {
                return ObjectFactory.CreateGameObject(name, components);
            }
        }
 
        private class FactorySwapToEditor : IDisposable
        {
            DefaultControls.IFactoryControls factory;
 
            public FactorySwapToEditor()
            {
                factory = DefaultControls.factory;
                DefaultControls.factory = DefaultEditorFactory.Default;
            }
 
            public void Dispose()
            {
                DefaultControls.factory = factory;
            }
        }
 
        private static void SetPositionVisibleinSceneView(RectTransform canvasRTransform, RectTransform itemTransform)
        {
            SceneView sceneView = SceneView.lastActiveSceneView;
 
            // Couldn't find a SceneView. Don't set position.
            if (sceneView == null || sceneView.camera == null)
                return;
 
            // Create world space Plane from canvas position.
            Vector2 localPlanePosition;
            Camera camera = sceneView.camera;
            Vector3 position = Vector3.zero;
            if (RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRTransform, new Vector2(camera.pixelWidth / 2, camera.pixelHeight / 2), camera, out localPlanePosition))
            {
                // Adjust for canvas pivot
                localPlanePosition.x = localPlanePosition.x + canvasRTransform.sizeDelta.x * canvasRTransform.pivot.x;
                localPlanePosition.y = localPlanePosition.y + canvasRTransform.sizeDelta.y * canvasRTransform.pivot.y;
 
                localPlanePosition.x = Mathf.Clamp(localPlanePosition.x, 0, canvasRTransform.sizeDelta.x);
                localPlanePosition.y = Mathf.Clamp(localPlanePosition.y, 0, canvasRTransform.sizeDelta.y);
 
                // Adjust for anchoring
                position.x = localPlanePosition.x - canvasRTransform.sizeDelta.x * itemTransform.anchorMin.x;
                position.y = localPlanePosition.y - canvasRTransform.sizeDelta.y * itemTransform.anchorMin.y;
 
                Vector3 minLocalPosition;
                minLocalPosition.x = canvasRTransform.sizeDelta.x * (0 - canvasRTransform.pivot.x) + itemTransform.sizeDelta.x * itemTransform.pivot.x;
                minLocalPosition.y = canvasRTransform.sizeDelta.y * (0 - canvasRTransform.pivot.y) + itemTransform.sizeDelta.y * itemTransform.pivot.y;
 
                Vector3 maxLocalPosition;
                maxLocalPosition.x = canvasRTransform.sizeDelta.x * (1 - canvasRTransform.pivot.x) - itemTransform.sizeDelta.x * itemTransform.pivot.x;
                maxLocalPosition.y = canvasRTransform.sizeDelta.y * (1 - canvasRTransform.pivot.y) - itemTransform.sizeDelta.y * itemTransform.pivot.y;
 
                position.x = Mathf.Clamp(position.x, minLocalPosition.x, maxLocalPosition.x);
                position.y = Mathf.Clamp(position.y, minLocalPosition.y, maxLocalPosition.y);
            }
 
            itemTransform.anchoredPosition = position;
            itemTransform.localRotation = Quaternion.identity;
            itemTransform.localScale = Vector3.one;
        }
 
        private static void PlaceUIElementRoot(GameObject element, MenuCommand menuCommand)
        {
            GameObject parent = menuCommand.context as GameObject;
            bool explicitParentChoice = true;
            if (parent == null)
            {
                parent = GetOrCreateCanvasGameObject();
                explicitParentChoice = false;
 
                // If in Prefab Mode, Canvas has to be part of Prefab contents,
                // otherwise use Prefab root instead.
                PrefabStage prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
                if (prefabStage != null && !prefabStage.IsPartOfPrefabContents(parent))
                    parent = prefabStage.prefabContentsRoot;
            }
            if (parent.GetComponentsInParent<Canvas>(true).Length == 0)
            {
                // Create canvas under context GameObject,
                // and make that be the parent which UI element is added under.
                GameObject canvas = MenuOptions.CreateNewUI();
                Undo.SetTransformParent(canvas.transform, parent.transform, "");
                parent = canvas;
            }
 
            GameObjectUtility.EnsureUniqueNameForSibling(element);
 
            SetParentAndAlign(element, parent);
            if (!explicitParentChoice) // not a context click, so center in sceneview
                SetPositionVisibleinSceneView(parent.GetComponent<RectTransform>(), element.GetComponent<RectTransform>());
 
            // This call ensure any change made to created Objects after they where registered will be part of the Undo.
            Undo.RegisterFullObjectHierarchyUndo(parent == null ? element : parent, "");
 
            // We have to fix up the undo name since the name of the object was only known after reparenting it.
            Undo.SetCurrentGroupName("Create " + element.name);
 
            Selection.activeGameObject = element;
        }
 
        private static void SetParentAndAlign(GameObject child, GameObject parent)
        {
            if (parent == null)
                return;
 
            Undo.SetTransformParent(child.transform, parent.transform, "");
 
            RectTransform rectTransform = child.transform as RectTransform;
            if (rectTransform)
            {
                rectTransform.anchoredPosition = Vector2.zero;
                Vector3 localPosition = rectTransform.localPosition;
                localPosition.z = 0;
                rectTransform.localPosition = localPosition;
            }
            else
            {
                child.transform.localPosition = Vector3.zero;
            }
            child.transform.localRotation = Quaternion.identity;
            child.transform.localScale = Vector3.one;
 
            SetLayerRecursively(child, parent.layer);
        }
 
        private static void SetLayerRecursively(GameObject go, int layer)
        {
            go.layer = layer;
            Transform t = go.transform;
            for (int i = 0; i < t.childCount; i++)
                SetLayerRecursively(t.GetChild(i).gameObject, layer);
        }
 
        // Graphic elements
 
        [MenuItem("GameObject/UI/Text", false, 2000)]
        static public void AddText(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreateText(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
        }
 
        [MenuItem("GameObject/UI/Image", false, 2001)]
        static public void AddImage(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreateImage(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
        }
 
        [MenuItem("GameObject/UI/Raw Image", false, 2002)]
        static public void AddRawImage(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreateRawImage(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
        }
 
        // Controls
 
        // Button and toggle are controls you just click on.
 
        [MenuItem("GameObject/UI/Button", false, 2030)]
        static public void AddButton(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreateButton(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
        }
 
        [MenuItem("GameObject/UI/Toggle", false, 2031)]
        static public void AddToggle(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreateToggle(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
        }
 
        // Slider and Scrollbar modify a number
 
        [MenuItem("GameObject/UI/Slider", false, 2033)]
        static public void AddSlider(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreateSlider(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
        }
 
        [MenuItem("GameObject/UI/Scrollbar", false, 2034)]
        static public void AddScrollbar(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreateScrollbar(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
        }
 
        // More advanced controls below
 
        [MenuItem("GameObject/UI/Dropdown", false, 2035)]
        static public void AddDropdown(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreateDropdown(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
        }
 
        [MenuItem("GameObject/UI/Input Field", false, 2036)]
        public static void AddInputField(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreateInputField(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
        }
 
        // Containers
 
        [MenuItem("GameObject/UI/Canvas", false, 2060)]
        static public void AddCanvas(MenuCommand menuCommand)
        {
            var go = CreateNewUI();
            SetParentAndAlign(go, menuCommand.context as GameObject);
            if (go.transform.parent as RectTransform)
            {
                RectTransform rect = go.transform as RectTransform;
                rect.anchorMin = Vector2.zero;
                rect.anchorMax = Vector2.one;
                rect.anchoredPosition = Vector2.zero;
                rect.sizeDelta = Vector2.zero;
            }
            Selection.activeGameObject = go;
        }
 
        [MenuItem("GameObject/UI/Panel", false, 2061)]
        static public void AddPanel(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreatePanel(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
 
            // Panel is special, we need to ensure there's no padding after repositioning.
            RectTransform rect = go.GetComponent<RectTransform>();
            rect.anchoredPosition = Vector2.zero;
            rect.sizeDelta = Vector2.zero;
        }
 
        [MenuItem("GameObject/UI/Scroll View", false, 2062)]
        static public void AddScrollView(MenuCommand menuCommand)
        {
            GameObject go;
            using (new FactorySwapToEditor())
                go = DefaultControls.CreateScrollView(GetStandardResources());
            PlaceUIElementRoot(go, menuCommand);
        }
 
        // Helper methods
 
        static public GameObject CreateNewUI()
        {
            // Root for the UI
            var root = ObjectFactory.CreateGameObject("Canvas", typeof(Canvas), typeof(CanvasScaler), typeof(GraphicRaycaster));
            root.layer = LayerMask.NameToLayer(kUILayerName);
            Canvas canvas = root.GetComponent<Canvas>();
            canvas.renderMode = RenderMode.ScreenSpaceOverlay;
 
            // Works for all stages.
            StageUtility.PlaceGameObjectInCurrentStage(root);
            bool customScene = false;
            PrefabStage prefabStage = PrefabStageUtility.GetCurrentPrefabStage();
            if (prefabStage != null)
            {
                Undo.SetTransformParent(root.transform, prefabStage.prefabContentsRoot.transform, "");
                customScene = true;
            }
 
            Undo.SetCurrentGroupName("Create " + root.name);
 
            // If there is no event system add one...
            // No need to place event system in custom scene as these are temporary anyway.
            // It can be argued for or against placing it in the user scenes,
            // but let's not modify scene user is not currently looking at.
            if (!customScene)
                CreateEventSystem(false);
            return root;
        }
 
        [MenuItem("GameObject/UI/Event System", false, 2100)]
        public static void CreateEventSystem(MenuCommand menuCommand)
        {
            GameObject parent = menuCommand.context as GameObject;
            CreateEventSystem(true, parent);
        }
 
        private static void CreateEventSystem(bool select)
        {
            CreateEventSystem(select, null);
        }
 
        private static void CreateEventSystem(bool select, GameObject parent)
        {
            StageHandle stage = parent == null ? StageUtility.GetCurrentStageHandle() : StageUtility.GetStageHandle(parent);
            var esys = stage.FindComponentOfType<EventSystem>();
            if (esys == null)
            {
                var eventSystem = ObjectFactory.CreateGameObject("EventSystem");
                if (parent == null)
                    StageUtility.PlaceGameObjectInCurrentStage(eventSystem);
                else
                    SetParentAndAlign(eventSystem, parent);
                esys = ObjectFactory.AddComponent<EventSystem>(eventSystem);
                ObjectFactory.AddComponent<StandaloneInputModule>(eventSystem);
 
                Undo.RegisterCreatedObjectUndo(eventSystem, "Create " + eventSystem.name);
            }
 
            if (select && esys != null)
            {
                Selection.activeGameObject = esys.gameObject;
            }
        }
 
        // Helper function that returns a Canvas GameObject; preferably a parent of the selection, or other existing Canvas.
        static public GameObject GetOrCreateCanvasGameObject()
        {
            GameObject selectedGo = Selection.activeGameObject;
 
            // Try to find a gameobject that is the selected GO or one if its parents.
            Canvas canvas = (selectedGo != null) ? selectedGo.GetComponentInParent<Canvas>() : null;
            if (IsValidCanvas(canvas))
                return canvas.gameObject;
 
            // No canvas in selection or its parents? Then use any valid canvas.
            // We have to find all loaded Canvases, not just the ones in main scenes.
            Canvas[] canvasArray = StageUtility.GetCurrentStageHandle().FindComponentsOfType<Canvas>();
            for (int i = 0; i < canvasArray.Length; i++)
                if (IsValidCanvas(canvasArray[i]))
                    return canvasArray[i].gameObject;
 
            // No canvas in the scene at all? Then create a new one.
            return MenuOptions.CreateNewUI();
        }
 
        static bool IsValidCanvas(Canvas canvas)
        {
            if (canvas == null || !canvas.gameObject.activeInHierarchy)
                return false;
 
            // It's important that the non-editable canvas from a prefab scene won't be rejected,
            // but canvases not visible in the Hierarchy at all do. Don't check for HideAndDontSave.
            if (EditorUtility.IsPersistent(canvas) || (canvas.hideFlags & HideFlags.HideInHierarchy) != 0)
                return false;
 
            return StageUtility.GetStageHandle(canvas.gameObject) == StageUtility.GetCurrentStageHandle();
        }
    }
}

using System;
using UnityEngine;
using UnityEngine.EventSystems;
 
namespace UnityEditor.EventSystems
{
    [CustomEditor(typeof(EventTrigger), true)]
    public class EventTriggerEditor : Editor
    {
        SerializedProperty m_DelegatesProperty;
 
        GUIContent m_IconToolbarMinus;
        GUIContent m_EventIDName;
        GUIContent[] m_EventTypes;
        GUIContent m_AddButonContent;
 
        protected virtual void OnEnable()
        {
            m_DelegatesProperty = serializedObject.FindProperty("m_Delegates");
            m_AddButonContent = EditorGUIUtility.TrTextContent("Add New Event Type");
            m_EventIDName = new GUIContent("");
            // Have to create a copy since otherwise the tooltip will be overwritten.
            m_IconToolbarMinus = new GUIContent(EditorGUIUtility.IconContent("Toolbar Minus"));
            m_IconToolbarMinus.tooltip = "Remove all events in this list.";
 
            string[] eventNames = Enum.GetNames(typeof(EventTriggerType));
            m_EventTypes = new GUIContent[eventNames.Length];
            for (int i = 0; i < eventNames.Length; ++i)
            {
                m_EventTypes[i] = new GUIContent(eventNames[i]);
            }
        }
 
        public override void OnInspectorGUI()
        {
            serializedObject.Update();
            int toBeRemovedEntry = -1;
 
            EditorGUILayout.Space();
 
            Vector2 removeButtonSize = GUIStyle.none.CalcSize(m_IconToolbarMinus);
 
            for (int i = 0; i < m_DelegatesProperty.arraySize; ++i)
            {
                SerializedProperty delegateProperty = m_DelegatesProperty.GetArrayElementAtIndex(i);
                SerializedProperty eventProperty = delegateProperty.FindPropertyRelative("eventID");
                SerializedProperty callbacksProperty = delegateProperty.FindPropertyRelative("callback");
                m_EventIDName.text = eventProperty.enumDisplayNames[eventProperty.enumValueIndex];
 
                EditorGUILayout.PropertyField(callbacksProperty, m_EventIDName);
                Rect callbackRect = GUILayoutUtility.GetLastRect();
 
                Rect removeButtonPos = new Rect(callbackRect.xMax - removeButtonSize.x - 8, callbackRect.y + 1, removeButtonSize.x, removeButtonSize.y);
                if (GUI.Button(removeButtonPos, m_IconToolbarMinus, GUIStyle.none))
                {
                    toBeRemovedEntry = i;
                }
 
                EditorGUILayout.Space();
            }
 
            if (toBeRemovedEntry > -1)
            {
                RemoveEntry(toBeRemovedEntry);
            }
 
            Rect btPosition = GUILayoutUtility.GetRect(m_AddButonContent, GUI.skin.button);
            const float addButonWidth = 200f;
            btPosition.x = btPosition.x + (btPosition.width - addButonWidth) / 2;
            btPosition.width = addButonWidth;
            if (GUI.Button(btPosition, m_AddButonContent))
            {
                ShowAddTriggermenu();
            }
 
            serializedObject.ApplyModifiedProperties();
        }
 
        private void RemoveEntry(int toBeRemovedEntry)
        {
            m_DelegatesProperty.DeleteArrayElementAtIndex(toBeRemovedEntry);
        }
 
        void ShowAddTriggermenu()
        {
            // Now create the menu, add items and show it
            GenericMenu menu = new GenericMenu();
            for (int i = 0; i < m_EventTypes.Length; ++i)
            {
                bool active = true;
 
                // Check if we already have a Entry for the current eventType, if so, disable it
                for (int p = 0; p < m_DelegatesProperty.arraySize; ++p)
                {
                    SerializedProperty delegateEntry = m_DelegatesProperty.GetArrayElementAtIndex(p);
                    SerializedProperty eventProperty = delegateEntry.FindPropertyRelative("eventID");
                    if (eventProperty.enumValueIndex == i)
                    {
                        active = false;
                    }
                }
                if (active)
                    menu.AddItem(m_EventTypes[i], false, OnAddNewSelected, i);
                else
                    menu.AddDisabledItem(m_EventTypes[i]);
            }
            menu.ShowAsContext();
            Event.current.Use();
        }
 
        private void OnAddNewSelected(object index)
        {
            int selected = (int)index;
 
            m_DelegatesProperty.arraySize += 1;
            SerializedProperty delegateEntry = m_DelegatesProperty.GetArrayElementAtIndex(m_DelegatesProperty.arraySize - 1);
            SerializedProperty eventProperty = delegateEntry.FindPropertyRelative("eventID");
            eventProperty.enumValueIndex = selected;
            serializedObject.ApplyModifiedProperties();
        }
    }
} 

using System;
using System.Collections.Generic;
using UnityEngine.Pool;
 
namespace UnityEngine.EventSystems
{
    public static class ExecuteEvents
    {
        public delegate void EventFunction<T1>(T1 handler, BaseEventData eventData);
 
        public static T ValidateEventData<T>(BaseEventData data) where T : class
        {
            if ((data as T) == null)
                throw new ArgumentException(String.Format("Invalid type: {0} passed to event expecting {1}", data.GetType(), typeof(T)));
            return data as T;
        }
 
        private static readonly EventFunction<IPointerMoveHandler> s_PointerMoveHandler = Execute;
 
        private static void Execute(IPointerMoveHandler handler, BaseEventData eventData)
        {
            handler.OnPointerMove(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IPointerEnterHandler> s_PointerEnterHandler = Execute;
 
        private static void Execute(IPointerEnterHandler handler, BaseEventData eventData)
        {
            handler.OnPointerEnter(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IPointerExitHandler> s_PointerExitHandler = Execute;
 
        private static void Execute(IPointerExitHandler handler, BaseEventData eventData)
        {
            handler.OnPointerExit(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IPointerDownHandler> s_PointerDownHandler = Execute;
 
        private static void Execute(IPointerDownHandler handler, BaseEventData eventData)
        {
            handler.OnPointerDown(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IPointerUpHandler> s_PointerUpHandler = Execute;
 
        private static void Execute(IPointerUpHandler handler, BaseEventData eventData)
        {
            handler.OnPointerUp(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IPointerClickHandler> s_PointerClickHandler = Execute;
 
        private static void Execute(IPointerClickHandler handler, BaseEventData eventData)
        {
            handler.OnPointerClick(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IInitializePotentialDragHandler> s_InitializePotentialDragHandler = Execute;
 
        private static void Execute(IInitializePotentialDragHandler handler, BaseEventData eventData)
        {
            handler.OnInitializePotentialDrag(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IBeginDragHandler> s_BeginDragHandler = Execute;
 
        private static void Execute(IBeginDragHandler handler, BaseEventData eventData)
        {
            handler.OnBeginDrag(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IDragHandler> s_DragHandler = Execute;
 
        private static void Execute(IDragHandler handler, BaseEventData eventData)
        {
            handler.OnDrag(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IEndDragHandler> s_EndDragHandler = Execute;
 
        private static void Execute(IEndDragHandler handler, BaseEventData eventData)
        {
            handler.OnEndDrag(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IDropHandler> s_DropHandler = Execute;
 
        private static void Execute(IDropHandler handler, BaseEventData eventData)
        {
            handler.OnDrop(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IScrollHandler> s_ScrollHandler = Execute;
 
        private static void Execute(IScrollHandler handler, BaseEventData eventData)
        {
            handler.OnScroll(ValidateEventData<PointerEventData>(eventData));
        }
 
        private static readonly EventFunction<IUpdateSelectedHandler> s_UpdateSelectedHandler = Execute;
 
        private static void Execute(IUpdateSelectedHandler handler, BaseEventData eventData)
        {
            handler.OnUpdateSelected(eventData);
        }
 
        private static readonly EventFunction<ISelectHandler> s_SelectHandler = Execute;
 
        private static void Execute(ISelectHandler handler, BaseEventData eventData)
        {
            handler.OnSelect(eventData);
        }
 
        private static readonly EventFunction<IDeselectHandler> s_DeselectHandler = Execute;
 
        private static void Execute(IDeselectHandler handler, BaseEventData eventData)
        {
            handler.OnDeselect(eventData);
        }
 
        private static readonly EventFunction<IMoveHandler> s_MoveHandler = Execute;
 
        private static void Execute(IMoveHandler handler, BaseEventData eventData)
        {
            handler.OnMove(ValidateEventData<AxisEventData>(eventData));
        }
 
        private static readonly EventFunction<ISubmitHandler> s_SubmitHandler = Execute;
 
        private static void Execute(ISubmitHandler handler, BaseEventData eventData)
        {
            handler.OnSubmit(eventData);
        }
 
        private static readonly EventFunction<ICancelHandler> s_CancelHandler = Execute;
 
        private static void Execute(ICancelHandler handler, BaseEventData eventData)
        {
            handler.OnCancel(eventData);
        }
 
        public static EventFunction<IPointerMoveHandler> pointerMoveHandler
        {
            get { return s_PointerMoveHandler; }
        }
 
        public static EventFunction<IPointerEnterHandler> pointerEnterHandler
        {
            get { return s_PointerEnterHandler; }
        }
 
        public static EventFunction<IPointerExitHandler> pointerExitHandler
        {
            get { return s_PointerExitHandler; }
        }
 
        public static EventFunction<IPointerDownHandler> pointerDownHandler
        {
            get { return s_PointerDownHandler; }
        }
 
        public static EventFunction<IPointerUpHandler> pointerUpHandler
        {
            get { return s_PointerUpHandler; }
        }
 
        public static EventFunction<IPointerClickHandler> pointerClickHandler
        {
            get { return s_PointerClickHandler; }
        }
 
        public static EventFunction<IInitializePotentialDragHandler> initializePotentialDrag
        {
            get { return s_InitializePotentialDragHandler; }
        }
 
        public static EventFunction<IBeginDragHandler> beginDragHandler
        {
            get { return s_BeginDragHandler; }
        }
 
        public static EventFunction<IDragHandler> dragHandler
        {
            get { return s_DragHandler; }
        }
 
        public static EventFunction<IEndDragHandler> endDragHandler
        {
            get { return s_EndDragHandler; }
        }
 
        public static EventFunction<IDropHandler> dropHandler
        {
            get { return s_DropHandler; }
        }
 
        public static EventFunction<IScrollHandler> scrollHandler
        {
            get { return s_ScrollHandler; }
        }
 
        public static EventFunction<IUpdateSelectedHandler> updateSelectedHandler
        {
            get { return s_UpdateSelectedHandler; }
        }
 
        public static EventFunction<ISelectHandler> selectHandler
        {
            get { return s_SelectHandler; }
        }
 
        public static EventFunction<IDeselectHandler> deselectHandler
        {
            get { return s_DeselectHandler; }
        }
 
        public static EventFunction<IMoveHandler> moveHandler
        {
            get { return s_MoveHandler; }
        }
 
        public static EventFunction<ISubmitHandler> submitHandler
        {
            get { return s_SubmitHandler; }
        }
 
        public static EventFunction<ICancelHandler> cancelHandler
        {
            get { return s_CancelHandler; }
        }
 
        private static void GetEventChain(GameObject root, IList<Transform> eventChain)
        {
            eventChain.Clear();
            if (root == null)
                return;
 
            var t = root.transform;
            while (t != null)
            {
                eventChain.Add(t);
                t = t.parent;
            }
        }
 
        public static bool Execute<T>(GameObject target, BaseEventData eventData, EventFunction<T> functor) where T : IEventSystemHandler
        {
            var internalHandlers = ListPool<IEventSystemHandler>.Get();
            GetEventList<T>(target, internalHandlers);
            //  if (s_InternalHandlers.Count > 0)
            //      Debug.Log("Executinng " + typeof (T) + " on " + target);
 
            var internalHandlersCount = internalHandlers.Count;
            for (var i = 0; i < internalHandlersCount; i++)
            {
                T arg;
                try
                {
                    arg = (T)internalHandlers[i];
                }
                catch (Exception e)
                {
                    var temp = internalHandlers[i];
                    Debug.LogException(new Exception(string.Format("Type {0} expected {1} received.", typeof(T).Name, temp.GetType().Name), e));
                    continue;
                }
 
                try
                {
                    functor(arg, eventData);
                }
                catch (Exception e)
                {
                    Debug.LogException(e);
                }
            }
 
            var handlerCount = internalHandlers.Count;
            ListPool<IEventSystemHandler>.Release(internalHandlers);
            return handlerCount > 0;
        }
 
        /// <summary>
        /// Execute the specified event on the first game object underneath the current touch.
        /// </summary>
        private static readonly List<Transform> s_InternalTransformList = new List<Transform>(30);
 
        public static GameObject ExecuteHierarchy<T>(GameObject root, BaseEventData eventData, EventFunction<T> callbackFunction) where T : IEventSystemHandler
        {
            GetEventChain(root, s_InternalTransformList);
 
            var internalTransformListCount = s_InternalTransformList.Count;
            for (var i = 0; i < internalTransformListCount; i++)
            {
                var transform = s_InternalTransformList[i];
                if (Execute(transform.gameObject, eventData, callbackFunction))
                    return transform.gameObject;
            }
            return null;
        }
 
        private static bool ShouldSendToComponent<T>(Component component) where T : IEventSystemHandler
        {
            var valid = component is T;
            if (!valid)
                return false;
 
            var behaviour = component as Behaviour;
            if (behaviour != null)
                return behaviour.isActiveAndEnabled;
            return true;
        }
 
        /// <summary>
        /// Get the specified object's event event.
        /// </summary>
        private static void GetEventList<T>(GameObject go, IList<IEventSystemHandler> results) where T : IEventSystemHandler
        {
            // Debug.LogWarning("GetEventList<" + typeof(T).Name + ">");
            if (results == null)
                throw new ArgumentException("Results array is null", "results");
 
            if (go == null || !go.activeInHierarchy)
                return;
 
            var components = ListPool<Component>.Get();
            go.GetComponents(components);
 
            var componentsCount = components.Count;
            for (var i = 0; i < componentsCount; i++)
            {
                if (!ShouldSendToComponent<T>(components[i]))
                    continue;
 
                // Debug.Log(string.Format("{2} found! On {0}.{1}", go, s_GetComponentsScratch[i].GetType(), typeof(T)));
                results.Add(components[i] as IEventSystemHandler);
            }
            ListPool<Component>.Release(components);
            // Debug.LogWarning("end GetEventList<" + typeof(T).Name + ">");
        }
 
        /// <summary>
        /// Whether the specified game object will be able to handle the specified event.
        /// </summary>
        public static bool CanHandleEvent<T>(GameObject go) where T : IEventSystemHandler
        {
            var internalHandlers = ListPool<IEventSystemHandler>.Get();
            GetEventList<T>(go, internalHandlers);
            var handlerCount = internalHandlers.Count;
            ListPool<IEventSystemHandler>.Release(internalHandlers);
            return handlerCount != 0;
        }
 
        /// <summary>
        /// Bubble the specified event on the game object, figuring out which object will actually receive the event.
        /// </summary>
        public static GameObject GetEventHandler<T>(GameObject root) where T : IEventSystemHandler
        {
            if (root == null)
                return null;
 
            Transform t = root.transform;
            while (t != null)
            {
                if (CanHandleEvent<T>(t.gameObject))
                    return t.gameObject;
                t = t.parent;
            }
            return null;
        }
    }
}