Asset System: New core type to represent assets (`AssetRepresenation`)

Introduces a new `AssetRepresentation` type, as a runtime only container
to hold asset information. It is supposed to become _the_ main way to
represent and refer to assets in the asset system, see T87235. It can
store things like the asset name, asset traits, preview and other asset
metadata.

Technical documentation:
https://wiki.blender.org/wiki/Source/Architecture/Asset_System/Back_End#Asset_Representation.

By introducing a proper asset representation type, we do an important
step away from the previous, non-optimal representation of assets as
files in the file browser backend, and towards the asset system as
backend. It should replace the temporary & hacky `AssetHandle` design in
the near future. Note that the loading of asset data still happens
through the file browser backend, check the linked to Wiki page for more
information on that.

As a side-effect, asset metadata isn't stored in file browser file
entries when browsing with link/append anymore. Don't think this was
ever used, but scripts may have accessed this. Can be brought back if
there's a need for it.

1 files changed, 80 insertions, 10 deletions

diff --git a/source/blender/blenkernel/intern/asset_library.cc b/source/blender/blenkernel/intern/asset_library.cc
index b8420af1168..4dccee425c6 100644
--- a/source/blender/blenkernel/intern/asset_library.cc
+++ b/source/blender/blenkernel/intern/asset_library.cc
@@ -7,11 +7,14 @@
 #include <memory>
 
 #include "BKE_asset_library.hh"
+#include "BKE_asset_representation.hh"
+#include "BKE_lib_remap.h"
 #include "BKE_main.h"
 #include "BKE_preferences.h"
 
 #include "BLI_fileops.h"
 #include "BLI_path_util.h"
+#include "BLI_set.hh"
 
 #include "DNA_asset_types.h"
 #include "DNA_userdef_types.h"
@@ -50,22 +53,22 @@ bool BKE_asset_library_has_any_unsaved_catalogs()
   return service->has_any_unsaved_catalogs();
 }
 
-bool BKE_asset_library_find_suitable_root_path_from_path(const char *input_path,
-                                                         char *r_library_path)
+std::string BKE_asset_library_find_suitable_root_path_from_path(
+    const blender::StringRefNull input_path)
 {
   if (bUserAssetLibrary *preferences_lib = BKE_preferences_asset_library_containing_path(
-          &U, input_path)) {
-    BLI_strncpy(r_library_path, preferences_lib->path, FILE_MAXDIR);
-    return true;
+          &U, input_path.c_str())) {
+    return preferences_lib->path;
   }
 
-  BLI_split_dir_part(input_path, r_library_path, FILE_MAXDIR);
-  return r_library_path[0] != '\0';
+  char buffer[FILE_MAXDIR];
+  BLI_split_dir_part(input_path.c_str(), buffer, FILE_MAXDIR);
+  return buffer;
 }
 
-bool BKE_asset_library_find_suitable_root_path_from_main(const Main *bmain, char *r_library_path)
+std::string BKE_asset_library_find_suitable_root_path_from_main(const Main *bmain)
 {
-  return BKE_asset_library_find_suitable_root_path_from_path(bmain->filepath, r_library_path);
+  return BKE_asset_library_find_suitable_root_path_from_path(bmain->filepath);
 }
 
 blender::bke::AssetCatalogService *BKE_asset_library_get_catalog_service(
@@ -98,6 +101,13 @@ void BKE_asset_library_refresh_catalog_simplename(struct AssetLibrary *asset_lib
   lib->refresh_catalog_simplename(asset_data);
 }
 
+void BKE_asset_library_remap_ids(IDRemapper *mappings)
+{
+  blender::bke::AssetLibraryService *service = blender::bke::AssetLibraryService::get();
+  service->foreach_loaded_asset_library(
+      [mappings](blender::bke::AssetLibrary &library) { library.remap_ids(*mappings); });
+}
+
 namespace blender::bke {
 
 AssetLibrary::AssetLibrary() : catalog_service(std::make_unique<AssetCatalogService>())
@@ -111,7 +121,7 @@ AssetLibrary::~AssetLibrary()
   }
 }
 
-void AssetLibrary::load(StringRefNull library_root_directory)
+void AssetLibrary::load_catalogs(StringRefNull library_root_directory)
 {
   auto catalog_service = std::make_unique<AssetCatalogService>(library_root_directory);
   catalog_service->load_from_disk();
@@ -123,6 +133,44 @@ void AssetLibrary::refresh()
   this->catalog_service->reload_catalogs();
 }
 
+AssetRepresentation &AssetLibrary::add_external_asset(StringRef name,
+                                                      std::unique_ptr<AssetMetaData> metadata)
+{
+  asset_storage_.append(std::make_unique<AssetRepresentation>(name, std::move(metadata)));
+  return *asset_storage_.last();
+}
+
+AssetRepresentation &AssetLibrary::add_local_id_asset(ID &id)
+{
+  asset_storage_.append(std::make_unique<AssetRepresentation>(id));
+  return *asset_storage_.last();
+}
+
+std::optional<int> AssetLibrary::find_asset_index(const AssetRepresentation &asset)
+{
+  int index = 0;
+  /* Find index of asset. */
+  for (auto &asset_uptr : asset_storage_) {
+    if (&asset == asset_uptr.get()) {
+      return index;
+    }
+    index++;
+  }
+
+  return {};
+}
+
+bool AssetLibrary::remove_asset(AssetRepresentation &asset)
+{
+  std::optional<int> asset_index = find_asset_index(asset);
+  if (!asset_index) {
+    return false;
+  }
+
+  asset_storage_.remove_and_reorder(*asset_index);
+  return true;
+}
+
 namespace {
 void asset_library_on_save_post(struct Main *main,
                                 struct PointerRNA **pointers,
@@ -166,6 +214,28 @@ void AssetLibrary::on_blend_save_post(struct Main *main,
   }
 }
 
+void AssetLibrary::remap_ids(IDRemapper &mappings)
+{
+  Set<AssetRepresentation *> removed_id_assets;
+
+  for (auto &asset_uptr : asset_storage_) {
+    if (!asset_uptr->is_local_id()) {
+      continue;
+    }
+
+    IDRemapperApplyResult result = BKE_id_remapper_apply(
+        &mappings, &asset_uptr->local_asset_id_, ID_REMAP_APPLY_DEFAULT);
+    if (result == ID_REMAP_RESULT_SOURCE_UNASSIGNED) {
+      removed_id_assets.add(asset_uptr.get());
+    }
+  }
+
+  /* Remove the assets from storage. */
+  for (AssetRepresentation *asset : removed_id_assets) {
+    remove_asset(*asset);
+  }
+}
+
 void AssetLibrary::refresh_catalog_simplename(struct AssetMetaData *asset_data)
 {
   if (BLI_uuid_is_nil(asset_data->catalog_id)) {