【Unity3D】用继承EditorUpdater类来实现Editor模式下的后台处理

EditorWindow类的OnGUI函数只会在窗口焦点处于Editor窗口上的时候才会运行。如果希望焦点不在Editor窗口上的时候，它也能实时更新，可以实现以下方法：

OnDestroy	OnDestroy is called when the EditorWindow is closed.
OnFocus	Called when the window gets keyboard focus.
OnGUI	Implement your own editor GUI here.
OnHierarchyChange	Called whenever the scene hierarchy has changed.
OnInspectorUpdate	OnInspectorUpdate is called at 10 frames per second to give the inspector a chance to update.
OnLostFocus	Called when the window loses keyboard focus.
OnProjectChange	Called whenever the project has changed.
OnSelectionChange	Called whenever the selection has changed.
Update	Called multiple times per second on all visible windows.

但是，如果Editor窗口被贴到大窗口上后，选择和它平级的窗口，从而隐藏了Editor窗口，这样OnGUI函数仍然无法调用。所以，我们为了实现更有效的后台处理，可以采用继承一个自己写的EditorUpdate类的方式。

using System;
using System.Collections;
using System.Reflection;
using UnityEditor;
using UnityEngine;

[InitializeOnLoad]
public class EditorMonoBehaviour 
{
    static EditorMonoBehaviour()
    {
        var type = Types.GetType ("UnityEditor.EditorAssemblies", "UnityEditor.dll");
        var method = type.GetMethod("SubclassesOf",BindingFlags.Static|BindingFlags.NonPublic|BindingFlags.Instance,null,new Type[]{typeof(Type)},null);
        var e = method.Invoke (null, new object[] { typeof(EditorMonoBehaviour) }) as IEnumerable;
        foreach (Type editorMonoBehaviourClass in e) 
        {
            method = editorMonoBehaviourClass.BaseType.GetMethod ("OnEditorMonoBehaviour", BindingFlags.NonPublic | BindingFlags.Instance);
            if (method != null) 
            {
                method.Invoke (System.Activator.CreateInstance (editorMonoBehaviourClass), new object[0]);
            }
        }
    }

    private void OnEditorMonoBehaviour()
    {
        EditorApplication.update += Update;
        EditorApplication.hierarchyWindowChanged += OnHierarchyWindowChanged;
        EditorApplication.hierarchyWindowItemOnGUI += HierarchyWindowItemOnGUI;
        EditorApplication.projectWindowChanged += OnProjectWindowChanged;
        EditorApplication.projectWindowItemOnGUI += ProjectWindowItemOnGUI;
        EditorApplication.modifierKeysChanged += OnModifierKeysChanged;

        EditorApplication.CallbackFunction function = () => OnGlobalEventHandler (Event.current);
        FieldInfo info = typeof(EditorApplication).GetField ("globalEventHandler", BindingFlags.Static | BindingFlags.Instance | BindingFlags.NonPublic);
        EditorApplication.CallbackFunction functions = (EditorApplication.CallbackFunction)info.GetValue (null);
        function += function;
        info.SetValue (null, (object)functions);
        EditorApplication.searchChanged += OnSearchChanged;
        EditorApplication.playmodeStateChanged += () => {
            if(EditorApplication.isPaused)
            {
                OnPlaymodeStateChanged(PlayModeState.Paused);
            }    
            if(EditorApplication.isPlaying)
            {
                OnPlaymodeStateChanged(PlayModeState.Playing);
            }
            if(EditorApplication.isPlayingOrWillChangePlaymode)
            {
                OnPlaymodeStateChanged(PlayModeState.PlayingOrWillChangePlayMode);
            }
        };

        Start ();
    }

    public virtual void Start()
    {}

    public virtual void Update()
    {}

    public virtual void OnHierarchyWindowChanged()
    {}

    public virtual void HierarchyWindowItemOnGUI(int instanceID,Rect selectionRect)
    {}

    public virtual void OnProjectWindowChanged()
    {}

    public virtual void ProjectWindowItemOnGUI(string guid,Rect selectionRect)
    {}

    public virtual void OnModifierKeysChanged()
    {}

    public virtual void OnGlobalEventHandler(Event e)
    {}

    public virtual void OnSearchChanged()
    {}

    public virtual void OnPlaymodeStateChanged(PlayModeState playModeState)
    {}

    public enum PlayModeState
    {
        Playing,
        Paused,
        Stop,
        PlayingOrWillChangePlayMode
    }
}

然后在另一个脚本中继承这个类，并重载Start和Update等方法，在这些方法中实现后台逻辑，就可以后台更新了。

using UnityEngine;
using System.Collections;

public class UpdaterTest :EditorMonoBehaviour
{
    public override void Update ()
    {
        
    }
}