Assets: Add further dedicated derived classes for asset libraries

Continuation of bdfb1f6a04. Adds derived classes for the essentials and
preferences asset libraries, to allow specialized classes with a simple
and common interface. This should help untangling the asset library
service code.

source/blender/asset_system/AS_asset_library.hh

@@ -65,6 +65,7 @@ class AssetLibrary {
    */
   std::unique_ptr<AssetStorage> asset_storage_;
 
+ protected:
   std::optional<eAssetImportMethod> import_method_;
   /** Assets owned by this library may be imported with a different method than set in
    * #import_method_ above, it's just a default. */

source/blender/asset_system/CMakeLists.txt

@@ -15,10 +15,11 @@ set(SRC
   intern/asset_catalog.cc
   intern/asset_catalog_path.cc
   intern/asset_catalog_tree.cc
-  intern/asset_essentials_library.cc
   intern/asset_identifier.cc
   intern/asset_library.cc
   intern/asset_library_all.cc
+  intern/asset_library_essentials.cc
+  intern/asset_library_from_preferences.cc
   intern/asset_library_on_disk.cc
   intern/asset_library_runtime.cc
   intern/asset_library_service.cc
@@ -34,6 +35,8 @@ set(SRC
   AS_asset_representation.hh
   AS_essentials_library.hh
   intern/asset_library_all.hh
+  intern/asset_library_essentials.hh
+  intern/asset_library_from_preferences.hh
   intern/asset_library_on_disk.hh
   intern/asset_library_runtime.hh
   intern/asset_library_service.hh

source/blender/asset_system/intern/asset_library_essentials.cc

@@ -6,14 +6,23 @@
  * \ingroup asset_system
  */
 
-#include "BLI_path_util.h"
-
 #include "BKE_appdir.hh"
 
+#include "utils.hh"
+
 #include "AS_essentials_library.hh"
+#include "asset_library_essentials.hh"
 
 namespace blender::asset_system {
 
+EssentialsAssetLibrary::EssentialsAssetLibrary()
+    : OnDiskAssetLibrary(ASSET_LIBRARY_ESSENTIALS,
+                         {},
+                         utils::normalize_directory_path(essentials_directory_path()))
+{
+  import_method_ = ASSET_IMPORT_APPEND_REUSE;
+}
+
 StringRefNull essentials_directory_path()
 {
   static std::string path = []() {

source/blender/asset_system/intern/asset_library_essentials.hh

@@ -0,0 +1,20 @@
+/* SPDX-FileCopyrightText: 2024 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup asset_system
+ */
+
+#pragma once
+
+#include "asset_library_on_disk.hh"
+
+namespace blender::asset_system {
+
+class EssentialsAssetLibrary : public OnDiskAssetLibrary {
+ public:
+  EssentialsAssetLibrary();
+};
+
+}  // namespace blender::asset_system

source/blender/asset_system/intern/asset_library_from_preferences.cc

@@ -0,0 +1,18 @@
+/* SPDX-FileCopyrightText: 2024 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup asset_system
+ */
+
+#include "asset_library_from_preferences.hh"
+
+namespace blender::asset_system {
+
+PreferencesOnDiskAssetLibrary::PreferencesOnDiskAssetLibrary(StringRef name, StringRef root_path)
+    : OnDiskAssetLibrary(ASSET_LIBRARY_CUSTOM, name, root_path)
+{
+}
+
+}  // namespace blender::asset_system

source/blender/asset_system/intern/asset_library_from_preferences.hh

@@ -0,0 +1,20 @@
+/* SPDX-FileCopyrightText: 2024 Blender Authors
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later */
+
+/** \file
+ * \ingroup asset_system
+ */
+
+#pragma once
+
+#include "asset_library_on_disk.hh"
+
+namespace blender::asset_system {
+
+class PreferencesOnDiskAssetLibrary : public OnDiskAssetLibrary {
+ public:
+  PreferencesOnDiskAssetLibrary(StringRef name = "", StringRef root_path = "");
+};
+
+}  // namespace blender::asset_system

source/blender/asset_system/intern/asset_library_service.cc

@@ -20,6 +20,8 @@
 #include "AS_asset_library.hh"
 #include "AS_essentials_library.hh"
 #include "asset_library_all.hh"
+#include "asset_library_essentials.hh"
+#include "asset_library_from_preferences.hh"
 #include "asset_library_on_disk.hh"
 #include "asset_library_runtime.hh"
 #include "asset_library_service.hh"
@@ -72,10 +74,7 @@ AssetLibrary *AssetLibraryService::get_asset_library(
         return nullptr;
       }
 
-      AssetLibrary *library = get_asset_library_on_disk_builtin(type, root_path);
-      library->import_method_ = ASSET_IMPORT_APPEND_REUSE;
-
-      return library;
+      return get_asset_library_on_disk_builtin(type, root_path);
     }
     case ASSET_LIBRARY_LOCAL: {
       /* For the "Current File" library  we get the asset library root path based on main. */
@@ -132,8 +131,19 @@ AssetLibrary *AssetLibraryService::get_asset_library_on_disk(eAssetLibraryType l
     return lib;
   }
 
-  std::unique_ptr lib_uptr = std::make_unique<OnDiskAssetLibrary>(
-      library_type, name, normalized_root_path);
+  std::unique_ptr<OnDiskAssetLibrary> lib_uptr;
+  switch (library_type) {
+    case ASSET_LIBRARY_CUSTOM:
+      lib_uptr = std::make_unique<PreferencesOnDiskAssetLibrary>(name, normalized_root_path);
+      break;
+    case ASSET_LIBRARY_ESSENTIALS:
+      lib_uptr = std::make_unique<EssentialsAssetLibrary>();
+      break;
+    default:
+      lib_uptr = std::make_unique<OnDiskAssetLibrary>(library_type, name, normalized_root_path);
+      break;
+  }
+
   AssetLibrary *lib = lib_uptr.get();
 
   lib->load_catalogs();