Makes things look more appealing visually. Plus it's a way to visually
group the tree rows together, which can be important if there are more
widgets surrounding the tree.
Issue was that the `on_activate()` callback of tree-items were
continuously called, because the active-state was queried before we
fully reconstructed the tree and its state from the previous redraw.
Such issues could happen in more places, so I've refactored the API a
bit to reflect the requirements for state queries, and include some
sanity checks.
The actual fix for the issue is to delay the state change until the tree
is fully reconstructed, by letting the tree-items pass a callback to
check if they should be active.
The `ui::BasicTreeViewItem` took a function-like object to execute on
item activation via the constructor. This was mainly intended to be used
with lambdas. However, it's confusing to just have this lambda there,
with no indication of what it's for (activation).
Instead, assign the function-like object via an explicit `on_activate()`
function.
Makes sure that the active item of a tree never has collapsed parent
items, which can be confusing if it happens. E.g. for the asset catalogs
UI, the active catalog decides which assets are visible. Having it
hidden while being the main factor deciding which assets are visible is
quite confusing.
I think it makes sense to have this at the UI Tree-View level, rather
than doing it manually in the asset catalog code for example. Seems like
something you'd commonly want. We can make it optional in the API if
needed.
Renamed the `set_active()` function to make clear that it is more than a
mere setter.
Adds an easy way to add drop support for tree-view rows.
Most of the work is handled by the tree-view UI code. The tree items can
simply override a few functions (`can_drop()`, `on_drop()`,
`drop_tooltip()`) to implement their custom drop behavior.
While dragging over a tree-view item that can be dropped into/onto, the
item can show a custom and dynamic tooltip explaining what's gonna
happen on drop.
This isn't used yet, but will soon be for asset catalogs.
See documentation here:
https://wiki.blender.org/wiki/Source/Interface/Views#Further_Customizations
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
