Asset Browser: Initial Asset Catalog UI

The Asset Browser now displays a tree with asset catalogs in the left
sidebar.
This replaces the asset categories. It uses the new UI tree-view API
(https://wiki.blender.org/wiki/Source/Interface/Views#Tree-View).
Buttons are displayed for adding and removing of catalogs. Parent items
can be collapsed, but the collapsed/uncollapsed state is not stored in
files yet.
Note that edits to catalogs (e.g. new or removed catalogs) are only
written to the asset library's catalog definition files when saving a
.blend.

In the "Current File" asset library, we try to show asset catalogs from
a parent asset library, or if that fails, from the directory the file is
stored in. See adaf4f56e1ed.

There are plenty of TODOs and smaller glitches to be fixed still. Plus a
UI polishing pass should be done.

Important missing UI features:
* Dragging assets into catalogs (WIP, close to being ready).
* Renaming catalogs
* Proper handling of catalogs in the "Current File" asset library
  (currently not working well).

The "Current File" asset library is especially limited still. Since this
is the only place where you can assign assets to a catalog, this makes
the catalogs very cumbersome in general. To assign an asset to a
catalog, one has to manually copy the Catalog ID (a random hash like
number) to the asset metadata through a temporary UI in the Asset
Browser Sidebar. These limitations should be addressed over the next few
days, they are high priority.

Differential Revision: https://developer.blender.org/D12670

3 files changed, 9 insertions, 1 deletions

diff --git a/source/blender/editors/include/ED_fileselect.h b/source/blender/editors/include/ED_fileselect.h
index 82057c726a5..423d619f41a 100644
--- a/source/blender/editors/include/ED_fileselect.h
+++ b/source/blender/editors/include/ED_fileselect.h
@@ -142,6 +142,7 @@ void ED_fileselect_exit(struct wmWindowManager *wm, struct SpaceFile *sfile);
 
 bool ED_fileselect_is_file_browser(const struct SpaceFile *sfile);
 bool ED_fileselect_is_asset_browser(const struct SpaceFile *sfile);
+struct AssetLibrary *ED_fileselect_active_asset_library_get(const struct SpaceFile *sfile);
 struct ID *ED_fileselect_active_asset_get(const struct SpaceFile *sfile);
 
 /* Activate the file that corresponds to the given ID.
diff --git a/source/blender/editors/include/UI_interface.h b/source/blender/editors/include/UI_interface.h
index f7842270746..106f6166760 100644
--- a/source/blender/editors/include/UI_interface.h
+++ b/source/blender/editors/include/UI_interface.h
@@ -2761,7 +2761,8 @@ void UI_interface_tag_script_reload(void);
 /* Support click-drag motion which presses the button and closes a popover (like a menu). */
 #define USE_UI_POPOVER_ONCE
 
-bool UI_tree_view_item_is_active(uiTreeViewItemHandle *item_);
+bool UI_tree_view_item_is_active(const uiTreeViewItemHandle *item);
+bool UI_tree_view_item_matches(const uiTreeViewItemHandle *a, const uiTreeViewItemHandle *b);
 
 #ifdef __cplusplus
 }
diff --git a/source/blender/editors/include/UI_tree_view.hh b/source/blender/editors/include/UI_tree_view.hh
index fac880a0a67..81a614cd195 100644
--- a/source/blender/editors/include/UI_tree_view.hh
+++ b/source/blender/editors/include/UI_tree_view.hh
@@ -190,6 +190,12 @@ class AbstractTreeViewItem : public TreeViewItemContainer {
    * last redraw to this item. If sub-classes introduce more advanced state they should override
    * this and make it update their state accordingly. */
   virtual void update_from_old(const AbstractTreeViewItem &old);
+  /** Compare this item to \a other to check if they represent the same data. This is critical for
+   * being able to recognize an item from a previous redraw, to be able to keep its state (e.g.
+   * open/closed, active, etc.). Items are only matched if their parents also match.
+   * By default this just matches the items names/labels (if their parents match!). If that isn't
+   * good enough for a sub-class, that can override it. */
+  virtual bool matches(const AbstractTreeViewItem &other) const;
 
   const AbstractTreeView &get_tree_view() const;
   int count_parents() const;