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 adaf4f56e1.
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
This follows three main targets:
* Make creation of new tree UIs easy.
* Groundwork to generalize tree UIs (so e.g. Outliner, animation
channels, asset catalogs and spreadsheet data-sets don't have to
re-implement basic tree UI code) or even other data-view UIs.
* Better separate data and UI state. E.g. with this, tree-item selection
or the open/collapsed state can be stored on the UI level, rather than
in data. (Asset Catalogs need this, storing UI state info in them is
not an option.)
In addition, the design should be well testable and could even be
exposed to Python.
Note that things will likely change in master still. E.g. the actually
resulting UI isn't very nice visually yet.
The design is documented here:
https://wiki.blender.org/wiki/Source/Interface/Views
Differential Revision: https://developer.blender.org/D12573
