Unity SceneViewのアイコンを表示・非表示するエディタ拡張

ChangeIconVisibility.cs

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

public static class ChangeIconVisibility
{
    // アイコンの表示・非表示フラグ
    static bool visibility = false;

    // ボタンに表示するテキスト
    static string buttonText = "Show Icon";

    [InitializeOnLoadMethod]
    static void Init()
    {
        SceneView.onSceneGUIDelegate += OnGUI;
    }

    static void OnGUI(SceneView sceneView)
    {
        var rect = new Rect(4, 20, 100, 0);

        GUI.WindowFunction func = id =>
        {
            if (GUILayout.Button(buttonText))
            {
                if(visibility == true)
                {
                    buttonText = "Show Icon";
                } else
                {
                    buttonText = "Hide Icon";
                }
                Func();
            }
        };
        GUILayout.Window(1, rect, func, string.Empty);
    }

    private static void Func()
    {
        var Annotation = Type.GetType("UnityEditor.Annotation, UnityEditor");
        var ClassId = Annotation.GetField("classID");
        var ScriptClass = Annotation.GetField("scriptClass");

        Type AnnotationUtility = Type.GetType("UnityEditor.AnnotationUtility, UnityEditor");
        var GetAnnotations = AnnotationUtility.GetMethod("GetAnnotations", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);
        var SetGizmoEnabled = AnnotationUtility.GetMethod("SetGizmoEnabled", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);
        var SetIconEnabled = AnnotationUtility.GetMethod("SetIconEnabled", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);

        Array annotations = (Array)GetAnnotations.Invoke(null, null);

        visibility = !visibility;

        foreach (var a in annotations)
        {
            var parameters = new object[]
            {
                (int)ClassId.GetValue(a),
                (string)ScriptClass.GetValue(a),
                Convert.ToInt32(visibility),
            };
            SetIconEnabled.Invoke(null, parameters);
        }
    }
}