PackageCreateMenu.cs

using System.Linq;
using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine;
using UnityEngine.SceneManagement;
 
namespace SCG.SpaceAdMobile
{
    public static class PackageCreateMenu
    {
        private const string RootName = "GameObject/" + nameof(SCG) + "/" + nameof(SpaceAdMobile);
 
        [MenuItem(RootName, false, 33)]
        private static void ShowCreatePopup()
        {
            var resource = AdAggregatorResource.Instance;
            if (resource == null || resource.Aggregators == null)
            {
                EditorUtility.DisplayDialog("Create", $"The resource file '{nameof(AdAggregatorResource)}' is missing. Please reinstall the package.", "OK");
                return;
            }
 
            var items = resource.Aggregators.Where(e => DefineSymbolsManager.HasDefineSymbol(e.Define))
                .SelectMany(e => e.Prefabs)
                .Where(p => p != null && PrefabUtility.GetPrefabAssetType(p) != PrefabAssetType.NotAPrefab)
                .Distinct()
                .OrderBy(p => p.name, System.StringComparer.OrdinalIgnoreCase)
                .ToArray();
 
            var fWindows = EditorWindow.focusedWindow != null ? EditorWindow.focusedWindow : null;
            var ctx = fWindows; if (ctx == null) ctx = SceneView.lastActiveSceneView;
 
            var center = ctx != null ? ctx.position.center : new Vector2(400, 300);
            var rect = new Rect(center.x, center.y, 1f, 1f);
 
            ShowMenu(rect, items);
        }
 
        [MenuItem(RootName, true)]
        private static bool Validate() => true;
 
        private static void ShowMenu(Rect screenRect, GameObject[] prefabs)
        {
            EditorApplication.delayCall += ShowMenuDelayCall;
            return;
 
            void ShowMenuDelayCall()
            {
                EditorApplication.delayCall -= ShowMenuDelayCall;
 
                var menu = new GenericMenu();
                foreach (var p in prefabs)
                {
                    if (!p) continue;
 
                    var label = new GUIContent($"Create {p.name}");
                    menu.AddItem(label, false, OnPick, p);
                }
 
                if (menu.GetItemCount() == 0)
                {
                    EditorUtility.DisplayDialog("Create", "No prefabs available.", "OK");
                    return;
                }
 
                // Show menu via a tiny popup host placed at screenRect
                GenericMenuPopupHost.Show(menu, screenRect);
            }
        }
 
        private static void OnPick(object userData) => Instantiate(userData as GameObject);
 
        private static void Instantiate(GameObject prefab)
        {
            if (prefab == null)
            {
                Debug.LogError("The selected prefab is missing.");
                return;
            }
 
            if (PrefabUtility.GetPrefabAssetType(prefab) == PrefabAssetType.NotAPrefab)
            {
                Debug.LogError($"'{prefab.name}' is not a prefab asset.");
                return;
            }
 
#if UNITY_2021_3_OR_NEWER
            var instance = (GameObject)PrefabUtility.InstantiatePrefab(prefab, SceneManager.GetActiveScene());
#else
            var instance = (GameObject)PrefabUtility.InstantiatePrefab(prefab);
#endif
            if (Selection.activeTransform)
                GameObjectUtility.SetParentAndAlign(instance, Selection.activeTransform.gameObject);
 
            PrefabUtility.UnpackPrefabInstance(instance, PrefabUnpackMode.Completely, InteractionMode.AutomatedAction);
            Undo.RegisterCreatedObjectUndo(instance, $"Create {prefab.name}");
            Selection.activeObject = instance;
            EditorSceneManager.MarkSceneDirty(instance.scene);
        }
    }

    internal sealed class GenericMenuPopupHost : EditorWindow
    {
        private GenericMenu _menu;
        private bool _shown;
 
        public static void Show(GenericMenu menu, Rect screenRect)
        {
            // Ensure non-zero size to avoid odd anchoring
            if (screenRect.width <= 0f || screenRect.height <= 0f)
                screenRect.size = Vector2.one;
 
            var w = CreateInstance<GenericMenuPopupHost>();
            w._menu = menu;
            w.position = screenRect;  // screen-space
            w.ShowPopup();            // borderless, always-on-top small window
            w.Focus();
        }
 
        private void OnGUI()
        {
            // Call DropDown ONCE from a real GUI context
            if (_shown) return;
            if (Event.current.type != EventType.Repaint) return;
 
            // Local (window) coordinates — anchor at (0,0) of this tiny host
            var local = new Rect(0f, 0f, Mathf.Max(1f, position.width), Mathf.Max(1f, position.height));
            _menu.DropDown(local);
            _shown = true;
 
            // Close on next tick to avoid stealing focus after selection
            EditorApplication.delayCall += Close;
        }
 
        private void OnLostFocus()
        {
            // Safety: if the menu closed without a selection, close host as well
            if (!_shown) return;
            Close();
        }
    }
}