Cleanup: Centralize/unify asset library reference from/to enum code

This was an open TODO, I wanted to have code for translating asset
library references from and to enum values in a central place, and
access that in the same way from both the Asset Browser and the
Workspace RNA code.

* Adds own file for the related functions.
* Adds doxygen comments.
* Updates RNA callbacks to properly use these functions.
* Let these functions call each other, avoid duplicating logic.

8 files changed, 172 insertions, 215 deletions

diff --git a/source/blender/editors/asset/CMakeLists.txt b/source/blender/editors/asset/CMakeLists.txt
index e0195f78cad..64024eea986 100644
--- a/source/blender/editors/asset/CMakeLists.txt
+++ b/source/blender/editors/asset/CMakeLists.txt
@@ -36,6 +36,7 @@ set(SRC
   asset_temp_id_consumer.cc
   intern/asset_handle.cc
   intern/asset_library_reference.cc
+  intern/asset_library_reference_enum.cc
 
   intern/asset_library_reference.hh
 )
diff --git a/source/blender/editors/asset/asset_edit.cc b/source/blender/editors/asset/asset_edit.cc
index 16fd71b4340..c55e7a95120 100644
--- a/source/blender/editors/asset/asset_edit.cc
+++ b/source/blender/editors/asset/asset_edit.cc
@@ -80,56 +80,3 @@ bool ED_asset_can_make_single_from_context(const bContext *C)
   /* Context needs a "id" pointer to be set for #ASSET_OT_mark()/#ASSET_OT_clear() to use. */
   return CTX_data_pointer_get_type_silent(C, "id", &RNA_ID).data != nullptr;
 }
-
-/* TODO better place? */
-/* TODO What about the setter and the `itemf` callback? */
-#include "BKE_preferences.h"
-#include "DNA_asset_types.h"
-#include "DNA_userdef_types.h"
-int ED_asset_library_reference_to_enum_value(const AssetLibraryReference *library)
-{
-  /* Simple case: Predefined repository, just set the value. */
-  if (library->type < ASSET_LIBRARY_CUSTOM) {
-    return library->type;
-  }
-
-  /* Note that the path isn't checked for validity here. If an invalid library path is used, the
-   * Asset Browser can give a nice hint on what's wrong. */
-  const bUserAssetLibrary *user_library = BKE_preferences_asset_library_find_from_index(
-      &U, library->custom_library_index);
-  if (user_library) {
-    return ASSET_LIBRARY_CUSTOM + library->custom_library_index;
-  }
-
-  BLI_assert(0);
-  return ASSET_LIBRARY_LOCAL;
-}
-
-AssetLibraryReference ED_asset_library_reference_from_enum_value(int value)
-{
-  AssetLibraryReference library;
-
-  /* Simple case: Predefined repository, just set the value. */
-  if (value < ASSET_LIBRARY_CUSTOM) {
-    library.type = value;
-    library.custom_library_index = -1;
-    BLI_assert(ELEM(value, ASSET_LIBRARY_LOCAL));
-    return library;
-  }
-
-  const bUserAssetLibrary *user_library = BKE_preferences_asset_library_find_from_index(
-      &U, value - ASSET_LIBRARY_CUSTOM);
-
-  /* Note that the path isn't checked for validity here. If an invalid library path is used, the
-   * Asset Browser can give a nice hint on what's wrong. */
-  const bool is_valid = (user_library->name[0] && user_library->path[0]);
-  if (!user_library) {
-    library.type = ASSET_LIBRARY_LOCAL;
-    library.custom_library_index = -1;
-  }
-  else if (user_library && is_valid) {
-    library.custom_library_index = value - ASSET_LIBRARY_CUSTOM;
-    library.type = ASSET_LIBRARY_CUSTOM;
-  }
-  return library;
-}
diff --git a/source/blender/editors/asset/intern/asset_library_reference_enum.cc b/source/blender/editors/asset/intern/asset_library_reference_enum.cc
new file mode 100644
index 00000000000..f3c6ec1952c
--- /dev/null
+++ b/source/blender/editors/asset/intern/asset_library_reference_enum.cc
@@ -0,0 +1,156 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup edasset
+ *
+ * Helpers to convert asset library references from and to enum values and RNA enums.
+ * In some cases it's simply not possible to reference an asset library with
+ * #AssetLibraryReferences. This API guarantees a safe translation to indices/enum values for as
+ * long as there is no change in the order of registered custom asset libraries.
+ */
+
+#include "BLI_listbase.h"
+
+#include "BKE_preferences.h"
+
+#include "DNA_asset_types.h"
+#include "DNA_userdef_types.h"
+
+#include "ED_asset.h"
+
+#include "UI_resources.h"
+
+#include "RNA_define.h"
+
+/**
+ * Return an index that can be used to uniquely identify \a library, assuming
+ * that all relevant indices were created with this function.
+ */
+int ED_asset_library_reference_to_enum_value(const AssetLibraryReference *library)
+{
+  /* Simple case: Predefined repository, just set the value. */
+  if (library->type < ASSET_LIBRARY_CUSTOM) {
+    return library->type;
+  }
+
+  /* Note that the path isn't checked for validity here. If an invalid library path is used, the
+   * Asset Browser can give a nice hint on what's wrong. */
+  const bUserAssetLibrary *user_library = BKE_preferences_asset_library_find_from_index(
+      &U, library->custom_library_index);
+  if (user_library) {
+    return ASSET_LIBRARY_CUSTOM + library->custom_library_index;
+  }
+
+  BLI_assert_unreachable();
+  return ASSET_LIBRARY_LOCAL;
+}
+
+/**
+ * Return an asset library reference matching the index returned by
+ * #ED_asset_library_reference_to_enum_value().
+ */
+AssetLibraryReference ED_asset_library_reference_from_enum_value(int value)
+{
+  AssetLibraryReference library;
+
+  /* Simple case: Predefined repository, just set the value. */
+  if (value < ASSET_LIBRARY_CUSTOM) {
+    library.type = value;
+    library.custom_library_index = -1;
+    BLI_assert(ELEM(value, ASSET_LIBRARY_LOCAL));
+    return library;
+  }
+
+  const bUserAssetLibrary *user_library = BKE_preferences_asset_library_find_from_index(
+      &U, value - ASSET_LIBRARY_CUSTOM);
+
+  /* Note that there is no check if the path exists here. If an invalid library path is used, the
+   * Asset Browser can give a nice hint on what's wrong. */
+  const bool is_valid = (user_library->name[0] && user_library->path[0]);
+  if (!user_library) {
+    library.type = ASSET_LIBRARY_LOCAL;
+    library.custom_library_index = -1;
+  }
+  else if (user_library && is_valid) {
+    library.custom_library_index = value - ASSET_LIBRARY_CUSTOM;
+    library.type = ASSET_LIBRARY_CUSTOM;
+  }
+  return library;
+}
+
+/**
+ * Translate all available asset libraries to an RNA enum, whereby the enum values match the result
+ * of #ED_asset_library_reference_to_enum_value() for any given library.
+ *
+ * Since this is meant for UI display, skips non-displayable libraries, that is, libraries with an
+ * empty name or path.
+ */
+const EnumPropertyItem *ED_asset_library_reference_to_rna_enum_itemf()
+{
+  const EnumPropertyItem predefined_items[] = {
+      /* For the future. */
+      // {ASSET_REPO_BUNDLED, "BUNDLED", 0, "Bundled", "Show the default user assets"},
+      {ASSET_LIBRARY_LOCAL,
+       "LOCAL",
+       ICON_BLENDER,
+       "Current File",
+       "Show the assets currently available in this Blender session"},
+      {0, NULL, 0, NULL, NULL},
+  };
+
+  EnumPropertyItem *item = NULL;
+  int totitem = 0;
+
+  /* Add separator if needed. */
+  if (!BLI_listbase_is_empty(&U.asset_libraries)) {
+    const EnumPropertyItem sepr = {0, "", 0, "Custom", NULL};
+    RNA_enum_item_add(&item, &totitem, &sepr);
+  }
+
+  int i = 0;
+  for (bUserAssetLibrary *user_library = (bUserAssetLibrary *)U.asset_libraries.first;
+       user_library;
+       user_library = user_library->next, i++) {
+    /* Note that the path itself isn't checked for validity here. If an invalid library path is
+     * used, the Asset Browser can give a nice hint on what's wrong. */
+    const bool is_valid = (user_library->name[0] && user_library->path[0]);
+    if (!is_valid) {
+      continue;
+    }
+
+    AssetLibraryReference library_reference;
+    library_reference.type = ASSET_LIBRARY_CUSTOM;
+    library_reference.custom_library_index = i;
+
+    const int enum_value = ED_asset_library_reference_to_enum_value(&library_reference);
+    /* Use library path as description, it's a nice hint for users. */
+    EnumPropertyItem tmp = {
+        enum_value, user_library->name, ICON_NONE, user_library->name, user_library->path};
+    RNA_enum_item_add(&item, &totitem, &tmp);
+  }
+
+  if (totitem) {
+    const EnumPropertyItem sepr = {0, "", 0, "Built-in", NULL};
+    RNA_enum_item_add(&item, &totitem, &sepr);
+  }
+
+  /* Add predefined items. */
+  RNA_enum_items_add(&item, &totitem, predefined_items);
+
+  RNA_enum_item_end(&item, &totitem);
+  return item;
+}
\ No newline at end of file
diff --git a/source/blender/editors/include/ED_asset.h b/source/blender/editors/include/ED_asset.h
index 4fdee03528d..40cc7f4194f 100644
--- a/source/blender/editors/include/ED_asset.h
+++ b/source/blender/editors/include/ED_asset.h
@@ -42,6 +42,7 @@ bool ED_asset_can_make_single_from_context(const struct bContext *C);
 
 int ED_asset_library_reference_to_enum_value(const struct AssetLibraryReference *library);
 struct AssetLibraryReference ED_asset_library_reference_from_enum_value(int value);
+const struct EnumPropertyItem *ED_asset_library_reference_to_rna_enum_itemf(void);
 
 const char *ED_asset_handle_get_name(const AssetHandle *asset);
 AssetMetaData *ED_asset_handle_get_metadata(const AssetHandle *asset);
diff --git a/source/blender/makesrna/intern/rna_asset.c b/source/blender/makesrna/intern/rna_asset.c
index f9658586f5f..484b7593812 100644
--- a/source/blender/makesrna/intern/rna_asset.c
+++ b/source/blender/makesrna/intern/rna_asset.c
@@ -160,71 +160,18 @@ static PointerRNA rna_AssetHandle_local_id_get(PointerRNA *ptr)
   return rna_pointer_inherit_refine(ptr, &RNA_ID, id);
 }
 
-int rna_asset_library_reference_get(const AssetLibraryReference *library)
-{
-  return ED_asset_library_reference_to_enum_value(library);
-}
-
-void rna_asset_library_reference_set(AssetLibraryReference *library, int value)
-{
-  *library = ED_asset_library_reference_from_enum_value(value);
-}
-
 const EnumPropertyItem *rna_asset_library_reference_itemf(bContext *UNUSED(C),
                                                           PointerRNA *UNUSED(ptr),
                                                           PropertyRNA *UNUSED(prop),
                                                           bool *r_free)
 {
-  const EnumPropertyItem predefined_items[] = {
-      /* For the future. */
-      // {ASSET_REPO_BUNDLED, "BUNDLED", 0, "Bundled", "Show the default user assets"},
-      {ASSET_LIBRARY_LOCAL,
-       "LOCAL",
-       ICON_BLENDER,
-       "Current File",
-       "Show the assets currently available in this Blender session"},
-      {0, NULL, 0, NULL, NULL},
-  };
-
-  EnumPropertyItem *item = NULL;
-  int totitem = 0;
-
-  /* Add separator if needed. */
-  if (!BLI_listbase_is_empty(&U.asset_libraries)) {
-    const EnumPropertyItem sepr = {0, "", 0, "Custom", NULL};
-    RNA_enum_item_add(&item, &totitem, &sepr);
+  const EnumPropertyItem *items = ED_asset_library_reference_to_rna_enum_itemf();
+  if (!items) {
+    *r_free = false;
   }
 
-  int i = 0;
-  for (bUserAssetLibrary *user_library = U.asset_libraries.first; user_library;
-       user_library = user_library->next, i++) {
-    /* Note that the path itself isn't checked for validity here. If an invalid library path is
-     * used, the Asset Browser can give a nice hint on what's wrong. */
-    const bool is_valid = (user_library->name[0] && user_library->path[0]);
-    if (!is_valid) {
-      continue;
-    }
-
-    /* Use library path as description, it's a nice hint for users. */
-    EnumPropertyItem tmp = {ASSET_LIBRARY_CUSTOM + i,
-                            user_library->name,
-                            ICON_NONE,
-                            user_library->name,
-                            user_library->path};
-    RNA_enum_item_add(&item, &totitem, &tmp);
-  }
-
-  if (totitem) {
-    const EnumPropertyItem sepr = {0, "", 0, "Built-in", NULL};
-    RNA_enum_item_add(&item, &totitem, &sepr);
-  }
-
-  /* Add predefined items. */
-  RNA_enum_items_add(&item, &totitem, predefined_items);
-
-  RNA_enum_item_end(&item, &totitem);
   *r_free = true;
-  return item;
+  return items;
 }
 
 #else
diff --git a/source/blender/makesrna/intern/rna_internal.h b/source/blender/makesrna/intern/rna_internal.h
index 9dc08430307..0bb76fd933a 100644
--- a/source/blender/makesrna/intern/rna_internal.h
+++ b/source/blender/makesrna/intern/rna_internal.h
@@ -270,8 +270,6 @@ void rna_def_view_layer_common(struct BlenderRNA *brna, struct StructRNA *srna,
 PropertyRNA *rna_def_asset_library_reference_common(struct StructRNA *srna,
                                                     const char *get,
                                                     const char *set);
-int rna_asset_library_reference_get(const struct AssetLibraryReference *library);
-void rna_asset_library_reference_set(struct AssetLibraryReference *library, int value);
 const EnumPropertyItem *rna_asset_library_reference_itemf(struct bContext *C,
                                                           struct PointerRNA *ptr,
                                                           struct PropertyRNA *prop,
diff --git a/source/blender/makesrna/intern/rna_space.c b/source/blender/makesrna/intern/rna_space.c
index f2d2b190d87..4aee7e9d852 100644
--- a/source/blender/makesrna/intern/rna_space.c
+++ b/source/blender/makesrna/intern/rna_space.c
@@ -536,6 +536,7 @@ static const EnumPropertyItem rna_enum_curve_display_handle_items[] = {
 #  include "DEG_depsgraph_build.h"
 
 #  include "ED_anim_api.h"
+#  include "ED_asset.h"
 #  include "ED_buttons.h"
 #  include "ED_clip.h"
 #  include "ED_fileselect.h"
@@ -2562,112 +2563,19 @@ static PointerRNA rna_FileSelectParams_filter_id_get(PointerRNA *ptr)
   return rna_pointer_inherit_refine(ptr, &RNA_FileSelectIDFilter, ptr->data);
 }
 
-/* TODO use rna_def_asset_library_reference_common() */
-
 static int rna_FileAssetSelectParams_asset_library_get(PointerRNA *ptr)
 {
   FileAssetSelectParams *params = ptr->data;
   /* Just an extra sanity check to ensure this isn't somehow called for RNA_FileSelectParams. */
   BLI_assert(ptr->type == &RNA_FileAssetSelectParams);
 
-  /* Simple case: Predefined repo, just set the value. */
-  if (params->asset_library.type < ASSET_LIBRARY_CUSTOM) {
-    return params->asset_library.type;
-  }
-
-  /* Note that the path isn't checked for validity here. If an invalid library path is used, the
-   * Asset Browser can give a nice hint on what's wrong. */
-  const bUserAssetLibrary *user_library = BKE_preferences_asset_library_find_from_index(
-      &U, params->asset_library.custom_library_index);
-  if (user_library) {
-    return ASSET_LIBRARY_CUSTOM + params->asset_library.custom_library_index;
-  }
-
-  BLI_assert(0);
-  return ASSET_LIBRARY_LOCAL;
+  return ED_asset_library_reference_to_enum_value(&params->asset_library);
 }
 
 static void rna_FileAssetSelectParams_asset_library_set(PointerRNA *ptr, int value)
 {
   FileAssetSelectParams *params = ptr->data;
-
-  /* Simple case: Predefined repo, just set the value. */
-  if (value < ASSET_LIBRARY_CUSTOM) {
-    params->asset_library.type = value;
-    params->asset_library.custom_library_index = -1;
-    BLI_assert(ELEM(value, ASSET_LIBRARY_LOCAL));
-    return;
-  }
-
-  const bUserAssetLibrary *user_library = BKE_preferences_asset_library_find_from_index(
-      &U, value - ASSET_LIBRARY_CUSTOM);
-
-  /* Note that the path isn't checked for validity here. If an invalid library path is used, the
-   * Asset Browser can give a nice hint on what's wrong. */
-  const bool is_valid = (user_library->name[0] && user_library->path[0]);
-  if (!user_library) {
-    params->asset_library.type = ASSET_LIBRARY_LOCAL;
-    params->asset_library.custom_library_index = -1;
-  }
-  else if (user_library && is_valid) {
-    params->asset_library.custom_library_index = value - ASSET_LIBRARY_CUSTOM;
-    params->asset_library.type = ASSET_LIBRARY_CUSTOM;
-  }
-}
-
-static const EnumPropertyItem *rna_FileAssetSelectParams_asset_library_itemf(
-    bContext *UNUSED(C), PointerRNA *UNUSED(ptr), PropertyRNA *UNUSED(prop), bool *r_free)
-{
-  const EnumPropertyItem predefined_items[] = {
-      /* For the future. */
-      // {ASSET_REPO_BUNDLED, "BUNDLED", 0, "Bundled", "Show the default user assets"},
-      {ASSET_LIBRARY_LOCAL,
-       "LOCAL",
-       ICON_BLENDER,
-       "Current File",
-       "Show the assets currently available in this Blender session"},
-      {0, NULL, 0, NULL, NULL},
-  };
-
-  EnumPropertyItem *item = NULL;
-  int totitem = 0;
-
-  /* Add separator if needed. */
-  if (!BLI_listbase_is_empty(&U.asset_libraries)) {
-    const EnumPropertyItem sepr = {0, "", 0, "Custom", NULL};
-    RNA_enum_item_add(&item, &totitem, &sepr);
-  }
-
-  int i = 0;
-  for (bUserAssetLibrary *user_library = U.asset_libraries.first; user_library;
-       user_library = user_library->next, i++) {
-    /* Note that the path itself isn't checked for validity here. If an invalid library path is
-     * used, the Asset Browser can give a nice hint on what's wrong. */
-    const bool is_valid = (user_library->name[0] && user_library->path[0]);
-    if (!is_valid) {
-      continue;
-    }
-
-    /* Use library path as description, it's a nice hint for users. */
-    EnumPropertyItem tmp = {ASSET_LIBRARY_CUSTOM + i,
-                            user_library->name,
-                            ICON_NONE,
-                            user_library->name,
-                            user_library->path};
-    RNA_enum_item_add(&item, &totitem, &tmp);
-  }
-
-  if (totitem) {
-    const EnumPropertyItem sepr = {0, "", 0, "Built-in", NULL};
-    RNA_enum_item_add(&item, &totitem, &sepr);
-  }
-
-  /* Add predefined items. */
-  RNA_enum_items_add(&item, &totitem, predefined_items);
-
-  RNA_enum_item_end(&item, &totitem);
-  *r_free = true;
-  return item;
+  params->asset_library = ED_asset_library_reference_from_enum_value(value);
 }
 
 static void rna_FileAssetSelectParams_asset_category_set(PointerRNA *ptr, uint64_t value)
@@ -6559,12 +6467,9 @@ static void rna_def_fileselect_asset_params(BlenderRNA *brna)
   RNA_def_struct_ui_text(
       srna, "Asset Select Parameters", "Settings for the file selection in Asset Browser mode");
 
-  prop = RNA_def_property(srna, "asset_library", PROP_ENUM, PROP_NONE);
-  RNA_def_property_enum_items(prop, DummyRNA_NULL_items);
-  RNA_def_property_enum_funcs(prop,
-                              "rna_FileAssetSelectParams_asset_library_get",
-                              "rna_FileAssetSelectParams_asset_library_set",
-                              "rna_FileAssetSelectParams_asset_library_itemf");
+  prop = rna_def_asset_library_reference_common(srna,
+                                                "rna_FileAssetSelectParams_asset_library_get",
+                                                "rna_FileAssetSelectParams_asset_library_set");
   RNA_def_property_ui_text(prop, "Asset Library", "");
   RNA_def_property_update(prop, NC_SPACE | ND_SPACE_FILE_PARAMS, NULL);
 
diff --git a/source/blender/makesrna/intern/rna_workspace.c b/source/blender/makesrna/intern/rna_workspace.c
index f23ce1dd12f..95f62d7de16 100644
--- a/source/blender/makesrna/intern/rna_workspace.c
+++ b/source/blender/makesrna/intern/rna_workspace.c
@@ -45,6 +45,8 @@
 #  include "DNA_screen_types.h"
 #  include "DNA_space_types.h"
 
+#  include "ED_asset.h"
+
 #  include "RNA_access.h"
 
 #  include "WM_toolsystem.h"
@@ -110,13 +112,13 @@ static void rna_WorkSpace_owner_ids_clear(WorkSpace *workspace)
 static int rna_WorkSpace_asset_library_get(PointerRNA *ptr)
 {
   const WorkSpace *workspace = ptr->data;
-  return rna_asset_library_reference_get(&workspace->asset_library);
+  return ED_asset_library_reference_to_enum_value(&workspace->asset_library);
 }
 
 static void rna_WorkSpace_asset_library_set(PointerRNA *ptr, int value)
 {
   WorkSpace *workspace = ptr->data;
-  rna_asset_library_reference_set(&workspace->asset_library, value);
+  workspace->asset_library = ED_asset_library_reference_from_enum_value(value);
 }
 
 static bToolRef *rna_WorkSpace_tools_from_tkey(WorkSpace *workspace,