指示预览分辨率应高于 256x256。
static Texture2D FetchPreview(SearchItem item, SearchContext context, Vector2 size, FetchPreviewOptions options) { var obj = ObjectFromItem(item); if (obj == null) return item.thumbnail; var assetPath = SearchUtils.GetHierarchyAssetPath(obj, true); if (string.IsNullOrEmpty(assetPath)) return item.thumbnail; if (options.HasFlag(FetchPreviewOptions.Large)) { if (AssetPreview.GetAssetPreview(obj) is Texture2D tex) return tex; } return GetAssetPreviewFromPath(assetPath, size, options); }