Asset System: New Asset Browser editor

This introduces the User Interface part of the Asset Browser, based on the
design in T54642.

Additions:
* New Asset Browser (internally a sub-editor of the File Browser).
* Navigation region showing asset categories.
* Main region showing the assets of the selected asset library with previews.
  The assets may be stored over multiple .blends in the directory that's
  "mounted" as asset library in the Preferences. They will all be shown in this
  list.
* Header with an asset library dropdown, allowing to choose the active asset
  library to show. Options are the "Current File" as asset library and all
  custom libraries.
* Display popover, filter popover and search box (partially dummies, see
  T82680).
* Sidebar showing the metadata of the currently active file (name, preview,
  description and tags), which can be edited for assets in the "Current File"
  asset library. (For others it will reset on reload.)
* The sidebar includes a button to load a custom preview image from a file.
* Make asset files draggable (with preview image).
* If a library with invalid path is selected, a message is drawn in the main
  region to help the user understand what's wrong.
* Operators to add and remove asset tags. Exposed in the sidebar.
* "Only Assets" option for Link/Append.
* Internal utilities for asset UI scripts.

For screenshots or demo videos, please see D9725. Or the 2.92 release notes.

Note that there are many things to be tweaked and polished in the Asset Browser
UI still. For example, the filter and display popovers are mostly dummies. See
T82680.

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/D9725

Reviewed by: Brecht Van Lommel, Hans Goudey

3 files changed, 67 insertions, 2 deletions

diff --git a/source/blender/makesrna/intern/rna_screen.c b/source/blender/makesrna/intern/rna_screen.c
index e300fb1b31b..784172b3ac9 100644
--- a/source/blender/makesrna/intern/rna_screen.c
+++ b/source/blender/makesrna/intern/rna_screen.c
@@ -270,6 +270,8 @@ static void rna_Area_ui_type_update(bContext *C, PointerRNA *ptr)
     st->space_subtype_set(area, area->butspacetype_subtype);
   }
   area->butspacetype_subtype = 0;
+
+  ED_area_tag_refresh(area);
 }
 
 static void rna_View2D_region_to_view(struct View2D *v2d, float x, float y, float result[2])
diff --git a/source/blender/makesrna/intern/rna_space.c b/source/blender/makesrna/intern/rna_space.c
index 4b39858026c..59012ce4528 100644
--- a/source/blender/makesrna/intern/rna_space.c
+++ b/source/blender/makesrna/intern/rna_space.c
@@ -2574,6 +2574,18 @@ static const EnumPropertyItem *rna_FileAssetSelectParams_asset_library_itemf(
   return item;
 }
 
+static void rna_FileAssetSelectParams_asset_category_set(PointerRNA *ptr, uint64_t value)
+{
+  FileSelectParams *params = ptr->data;
+  params->filter_id = value;
+}
+
+static uint64_t rna_FileAssetSelectParams_asset_category_get(PointerRNA *ptr)
+{
+  FileSelectParams *params = ptr->data;
+  return params->filter_id;
+}
+
 static void rna_FileBrowser_FileSelectEntry_name_get(PointerRNA *ptr, char *value)
 {
   const FileDirEntry *entry = ptr->data;
@@ -6207,6 +6219,47 @@ static void rna_def_fileselect_asset_params(BlenderRNA *brna)
   StructRNA *srna;
   PropertyRNA *prop;
 
+  /* XXX copied from rna_def_fileselect_idfilter. */
+  static const EnumPropertyItem asset_category_items[] = {
+      {FILTER_ID_SCE, "SCENES", ICON_SCENE_DATA, "Scenes", "Show scenes"},
+      {FILTER_ID_AC, "ANIMATIONS", ICON_ANIM_DATA, "Animations", "Show animation data"},
+      {FILTER_ID_OB | FILTER_ID_GR,
+       "OBJECTS_AND_COLLECTIONS",
+       ICON_GROUP,
+       "Objects & Collections",
+       "Show objects and collections"},
+      {FILTER_ID_AR | FILTER_ID_CU | FILTER_ID_LT | FILTER_ID_MB | FILTER_ID_ME
+       /* XXX avoid warning */
+       // | FILTER_ID_HA | FILTER_ID_PT | FILTER_ID_VO
+       ,
+       "GEOMETRY",
+       ICON_MESH_DATA,
+       "Geometry",
+       "Show meshes, curves, lattice, armatures and metaballs data"},
+      {FILTER_ID_LS | FILTER_ID_MA | FILTER_ID_NT | FILTER_ID_TE,
+       "SHADING",
+       ICON_MATERIAL_DATA,
+       "Shading",
+       "Show materials, nodetrees, textures and Freestyle's linestyles"},
+      {FILTER_ID_IM | FILTER_ID_MC | FILTER_ID_MSK | FILTER_ID_SO,
+       "IMAGES_AND_SOUNDS",
+       ICON_IMAGE_DATA,
+       "Images & Sounds",
+       "Show images, movie clips, sounds and masks"},
+      {FILTER_ID_CA | FILTER_ID_LA | FILTER_ID_LP | FILTER_ID_SPK | FILTER_ID_WO | FILTER_ID_WS,
+       "ENVIRONMENTS",
+       ICON_WORLD_DATA,
+       "Environment",
+       "Show worlds, lights, cameras and speakers"},
+      {FILTER_ID_BR | FILTER_ID_GD | FILTER_ID_PA | FILTER_ID_PAL | FILTER_ID_PC | FILTER_ID_TXT |
+           FILTER_ID_VF | FILTER_ID_CF,
+       "MISC",
+       ICON_GREASEPENCIL,
+       "Miscellaneous",
+       "Show other data types"},
+      {0, NULL, 0, NULL, NULL},
+  };
+
   srna = RNA_def_struct(brna, "FileAssetSelectParams", "FileSelectParams");
   RNA_def_struct_ui_text(
       srna, "Asset Select Parameters", "Settings for the file selection in Asset Browser mode");
@@ -6219,6 +6272,15 @@ static void rna_def_fileselect_asset_params(BlenderRNA *brna)
                               "rna_FileAssetSelectParams_asset_library_itemf");
   RNA_def_property_ui_text(prop, "Asset Library", "");
   RNA_def_property_update(prop, NC_SPACE | ND_SPACE_FILE_PARAMS, NULL);
+
+  prop = RNA_def_property(srna, "asset_category", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, asset_category_items);
+  RNA_def_property_enum_funcs(prop,
+                              "rna_FileAssetSelectParams_asset_category_get",
+                              "rna_FileAssetSelectParams_asset_category_set",
+                              NULL);
+  RNA_def_property_ui_text(prop, "Asset Category", "Determine which kind of assets to display");
+  RNA_def_property_update(prop, NC_SPACE | ND_SPACE_FILE_LIST, NULL);
 }
 
 static void rna_def_filemenu_entry(BlenderRNA *brna)
diff --git a/source/blender/makesrna/intern/rna_userdef.c b/source/blender/makesrna/intern/rna_userdef.c
index 2175cddcd7f..7a285df235a 100644
--- a/source/blender/makesrna/intern/rna_userdef.c
+++ b/source/blender/makesrna/intern/rna_userdef.c
@@ -5993,8 +5993,9 @@ static void rna_def_userdef_filepaths_asset_library(BlenderRNA *brna)
   RNA_def_struct_name_property(srna, prop);
   RNA_def_property_update(prop, 0, "rna_userdef_update");
 
-  prop = RNA_def_property(srna, "path", PROP_STRING, PROP_FILEPATH);
-  RNA_def_property_ui_text(prop, "Path", "Path to a .blend file to use as an asset library");
+  prop = RNA_def_property(srna, "path", PROP_STRING, PROP_DIRPATH);
+  RNA_def_property_ui_text(
+      prop, "Path", "Path to a directory with .blend files to use as an asset library");
   RNA_def_property_update(prop, 0, "rna_userdef_update");
 }