Asset System: Support custom asset library paths through Preferences

One of the core design aspects of the Asset Browser is that users can "mount"
custom asset libraries via the Preferences. Currently an asset library is just
a directory with one or more .blend files in it. We could easily support a
single .blend file as asset library as well (rather than a directory). It's
just disabled currently.

Note that in earlier designs, asset libraries were called repositories.

Idea is simple: In Preferences > File Paths, you can create custom libraries,
by setting a name and selecting a path. The name is ensured to be unique. If
the name or path are empty, the Asset Browser will not show it in the list of
available asset libraries.
The library path is not checked for validity, the Asset Browser will allow
selecting invalid libraries, but show a message instead of the file list, to
help the user understand what's going on.
Of course the actual Asset Browser UI is not part of this commit, it's in one
of the following ones.

{F9497950}

Part of the first Asset Browser milestone. Check the #asset_browser_milestone_1
project milestone on developer.blender.org.

Differential Revision: https://developer.blender.org/D9722

Reviewed by: Brecht Van Lommel, Hans Goudey

3 files changed, 123 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/blender.c b/source/blender/blenkernel/intern/blender.c
index f4f25c3a153..5b5bd416ef2 100644
--- a/source/blender/blenkernel/intern/blender.c
+++ b/source/blender/blenkernel/intern/blender.c
@@ -296,6 +296,7 @@ void BKE_blender_userdef_data_free(UserDef *userdef, bool clear_fonts)
   }
 
   BLI_freelistN(&userdef->autoexec_paths);
+  BLI_freelistN(&userdef->asset_libraries);
 
   BLI_freelistN(&userdef->uistyles);
   BLI_freelistN(&userdef->uifonts);
diff --git a/source/blender/blenkernel/intern/blendfile.c b/source/blender/blenkernel/intern/blendfile.c
index 567773507cf..0855db1a943 100644
--- a/source/blender/blenkernel/intern/blendfile.c
+++ b/source/blender/blenkernel/intern/blendfile.c
@@ -52,6 +52,7 @@
 #include "BKE_layer.h"
 #include "BKE_lib_id.h"
 #include "BKE_main.h"
+#include "BKE_preferences.h"
 #include "BKE_report.h"
 #include "BKE_scene.h"
 #include "BKE_screen.h"
@@ -645,6 +646,8 @@ UserDef *BKE_blendfile_userdef_from_defaults(void)
   /* Default studio light. */
   BKE_studiolight_default(userdef->light_param, userdef->light_ambient);
 
+  BKE_preferences_asset_library_default_add(userdef);
+
   return userdef;
 }
 
diff --git a/source/blender/blenkernel/intern/preferences.c b/source/blender/blenkernel/intern/preferences.c
new file mode 100644
index 00000000000..c263ff7100f
--- /dev/null
+++ b/source/blender/blenkernel/intern/preferences.c
@@ -0,0 +1,119 @@
+/*
+ * 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 bke
+ *
+ * User defined asset library API.
+ */
+
+#include <string.h>
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_listbase.h"
+#include "BLI_path_util.h"
+#include "BLI_string.h"
+#include "BLI_string_utf8.h"
+#include "BLI_string_utils.h"
+
+#include "BKE_appdir.h"
+#include "BKE_preferences.h"
+
+#include "BLT_translation.h"
+
+#include "DNA_userdef_types.h"
+
+#define U BLI_STATIC_ASSERT(false, "Global 'U' not allowed, only use arguments passed in!")
+
+/* -------------------------------------------------------------------- */
+/** \name Asset Libraries
+ * \{ */
+
+bUserAssetLibrary *BKE_preferences_asset_library_add(UserDef *userdef,
+                                                     const char *name,
+                                                     const char *path)
+{
+  bUserAssetLibrary *library = MEM_callocN(sizeof(*library), "bUserAssetLibrary");
+
+  BLI_addtail(&userdef->asset_libraries, library);
+
+  if (name) {
+    BKE_preferences_asset_library_name_set(userdef, library, name);
+  }
+  if (path) {
+    BLI_strncpy(library->path, path, sizeof(library->path));
+  }
+
+  return library;
+}
+
+void BKE_preferences_asset_library_name_set(UserDef *userdef,
+                                            bUserAssetLibrary *library,
+                                            const char *name)
+{
+  BLI_strncpy_utf8(library->name, name, sizeof(library->name));
+  BLI_uniquename(&userdef->asset_libraries,
+                 library,
+                 name,
+                 '.',
+                 offsetof(bUserAssetLibrary, name),
+                 sizeof(library->name));
+}
+
+/**
+ * Unlink and free a library preference member.
+ * \note Free's \a library itself.
+ */
+void BKE_preferences_asset_library_remove(UserDef *userdef, bUserAssetLibrary *library)
+{
+  BLI_freelinkN(&userdef->asset_libraries, library);
+}
+
+bUserAssetLibrary *BKE_preferences_asset_library_find_from_index(const UserDef *userdef, int index)
+{
+  return BLI_findlink(&userdef->asset_libraries, index);
+}
+
+bUserAssetLibrary *BKE_preferences_asset_library_find_from_name(const UserDef *userdef,
+                                                                const char *name)
+{
+  return BLI_findstring(&userdef->asset_libraries, name, offsetof(bUserAssetLibrary, name));
+}
+
+int BKE_preferences_asset_library_get_index(const UserDef *userdef,
+                                            const bUserAssetLibrary *library)
+{
+  return BLI_findindex(&userdef->asset_libraries, library);
+}
+
+void BKE_preferences_asset_library_default_add(UserDef *userdef)
+{
+  const char *asset_blend_name = "assets.blend";
+  const char *doc_path = BKE_appdir_folder_default();
+
+  /* No home or documents path found, not much we can do. */
+  if (!doc_path || !doc_path[0]) {
+    return;
+  }
+
+  /* Add new "Default" library under '[doc_path]/assets.blend'. */
+
+  bUserAssetLibrary *library = BKE_preferences_asset_library_add(userdef, DATA_("Default"), NULL);
+  BLI_join_dirfile(library->path, sizeof(library->path), doc_path, asset_blend_name);
+}
+
+/** \} */