Similar to fetchThumbnail, fetchPreview usually returns a bigger preview. The Search UI will progressively show one preview each frame, preventing the UI from blocking if many previews need to be generated at the same time.
[SearchItemProvider] internal static SearchProvider CreateProvider() { return new SearchProvider(id, name) { filterId = "tree:", priority = 99999, // put example provider at a low priority fetchItems = (context, items, provider) => { // That provider searches for tree prefabs in the project var results = AssetDatabase.FindAssets("t:Prefab tree" + context.searchQuery); foreach (var guid in results) { items.Add(provider.CreateItem(context, AssetDatabase.GUIDToAssetPath(guid), null, null, null, null)); } return null; }, #pragma warning disable UNT0008 // Null propagation on Unity objects // Use fetch to load the asset asynchronously on display fetchThumbnail = (item, context) => AssetDatabase.GetCachedIcon(item.id) as Texture2D, fetchPreview = (item, context, size, options) => AssetDatabase.GetCachedIcon(item.id) as Texture2D, fetchLabel = (item, context) => AssetDatabase.LoadMainAssetAtPath(item.id)?.name, fetchDescription = (item, context) => AssetDatabase.LoadMainAssetAtPath(item.id)?.name, toObject = (item, type) => AssetDatabase.LoadMainAssetAtPath(item.id), #pragma warning restore UNT0008 // Null propagation on Unity objects // Shows handled actions in the preview inspector // Shows inspector view in the preview inspector (uses toObject) showDetailsOptions = ShowDetailsOptions.Inspector | ShowDetailsOptions.Actions, trackSelection = (item, context) => { var obj = AssetDatabase.LoadMainAssetAtPath(item.id); if (obj != null) EditorGUIUtility.PingObject(obj.GetInstanceID()); }, startDrag = (item, context) => { var obj = AssetDatabase.LoadMainAssetAtPath(item.id); if (obj != null) { DragAndDrop.PrepareStartDrag(); DragAndDrop.objectReferences = new Object[] { obj }; DragAndDrop.StartDrag(item.label); } } }; }