Blender Git Loki

UI: Flip driver editor debug lines

In driver editor, vertically flip the value debug lines to align
them with the timeline header values. This makes it easier to read
the values. Also set the line width explicitly, which was incorrect
in some cases.

Differential Revision: https://developer.blender.org/D8877

Asset Browser: Python mixin utility for category-specific panels

Using this mixin for a panel definition, it's possible to set in which
categories the panel should appear. This is used by the Pose Library
add-on.

Fix failing tests from vertex group name parameter copy

It turns out `BKE_mesh_copy_parameters` can be called while other
tools are running calculations, which meant that it was called at the
same time as `armature_deform_coords_impl`. Beause of that, we
shouldn't do any freeing (of the old vertex group names) there.

Since the materials are copied in the "for_eval" version anyway,
it seems to make sense to copy the vertex group name list there also.

Fixes T89877, and also the failing `deform_modifiers` test.

Differential Revision: https://developer.blender.org/D11936

Cleanup: Remove use of designated initializers in C++ code

Does not compile on Windows.

Fix T88281: Pose Library 'flip pose' sometimes flips wrong

Correct cases where the X-axis of the bone (in pose space) aligns with
the pose-space Y or Z-axis. In these cases the decomposition of the
matrix fails, and a negative scale of the X-axis turns into a 180�
rotation around the Y-axis. An extra -1 scale to the X and Z axes of the
resulting matrix seems to fix things.

Cleanup: unused variable capture

Cleanup: Clang tidy

UI: Auto-scroll to keep active text buttons in view

If a text button is activated that is not in view (i.e. scrolled away),
the scrolling will now be adjusted to have it in view (with some
small additional margin). While entering text, the view may also be
updated should the button move out of view, for whatever reason. For the
most part, this feature shouldn't be needed and won't kick in, except
when a clicked on text button is partially out of view or very close to
the region edge. It's however quite important for the previously
committed feature, that is, pressing Ctrl+F to start searching in a UI
list. The end of the list where the scroll button appears may not be in
view. Plus while filtering the number of visible items changes so the
scrolling has to be updated to keep the search button visible.

Note that I disabled the auto-scrolling for when the text button spawned
an additional popup, like for search-box buttons. That is because
current code assumes the button to have a fixed position while the popup
is open. There is no code to update the popup position together with the
button/scrolling.

I also think that the logic added here could be used in more places,
e.g. for the "ensure file in view" logic the File Browser does.

Assets: Show asset path in asset browser sidebar

It's useful to know where an asset is stored in, before this there was no way
to tell this. This could probably be displayed nicer in the UI but we're
currently unsure how. But at least the information is there now.

Assets: temporarily apply pose when generating preview image

When generating a preview image for a pose, temporarily apply it to the
armature. Contrary to the usual pose application, this ignores the
selected bones and always applies the entire pose.

UI: New button/widget type for Asset Browser like preview tiles

This button type shows a preview image above centered text, similar to
the File Browser files in Thumbnail Display Mode or the default Asset
Browser display. In fact we may want to port these over to use the new
button type at some point.

Will be used by the asset view UI template that will be added in a
following commit. That is basically a mini version of the Asset Browser
that can be displayed elsewhere in the UI.

Assets: Open Blend File operator

Add operator 'Open Blend File' to the Asset Browser. This operator:
- starts a new Blender process,
- opens the blend file containing the asset,
- monitors the new Blender process, and when it stops,
- reloads the assets to show any changes made.

UI: Support pressing Ctrl+F over UI lists to search

Adds an operator invoked by default with Ctrl+F that while hovering a UI
list, opens the search field of the list and enables text input for it.
With this commit the search button may actually be out of view after
Ctrl+F still. The following commit adds auto-scroll to solve that.

A downside is that in the Properties, there also is Ctrl+F to start
the editor-wide search. That's not unusual in Blender though (e.g.
scolling with the mouse over a UI list also scrolls the list, not the
region).

Animation: add function to blend Action into pose

Add function `BKE_pose_apply_action_blend()`, which blends a given
Action into current pose. The Action is evaluated at a specified frame,
and the result is applied to the armature's pose.

A blend factor can be given to blend between the current pose and the
one in the Action. Quaternions are interpolated with SLERP; it is
assumed that their FCurves are consecutively stored in the Action.

This function will be used in the upcoming new Pose Library.

UI: New UI list layout type for big preview tiles

This new layout type is meant for the upcoming asset view UI template.
With it it is possible to show big asset previews with their names in a
responsive grid layout.

Notes:
* The layout is only available for C defined UI lists. We could expose
it to Python, but I think there are still some scrolling issues to be
fixed first. (The asset view template doesn't use scrolling for the UI
list.)
* I'd consider this a more usable version of the existing `GRID` layout
type. We may remove that in favor of the new one in future.

UI: Support defining UI lists in C

So far all UI lists had to be defined in Python, this makes it possible
to define them in C as well. Note that there is a whole bunch of special
handling for the Python API that isn't there for C. I think most
importantly custom properties support, which currently can't be added
for C defined UI lists.

The upcoming asset view UI template will use this, which needs to be
defined in C.

Adds a new file `interface_template_list.cc`, which at this point is
mostly a dummy to have a place for the `ED_uilisttypes_ui()` definition.
I plan a separate cleanup to move the UI-list template to that file.

UI: Support UI list tooltips, defined via Python scripts

Makes it possible to create tooltips for UI list rows, which can be
filled in .py scripts, similar to how they can extend other menus. This
is used by the (to be committed) Pose Library add-on to display pose
operations (selecting bones of a pose, blending a pose, etc).

It's important that the Python scripts check if the UI list is the
correct one by checking the list ID.
For this to work, a new `bpy.context.ui_list` can be checked. For
example, the Pose Library add-on does the following check:
```
def is_pose_asset_view() -> bool:
# Important: Must check context first, or the menu is added for every kind of list.
list = getattr(context, "ui_list", None)
if not list or list.bl_idname != "UI_UL_asset_view" or list.list_id != "pose_assets":
return False
if not context.asset_handle:
return False
return True
```

Assets: Abstraction for temporary loading of asset data-blocks

This is an editor-level abstraction for the `BLO_library_temp_xxx()`
API for temporary loading of data-blocks from another Blend file. It
abstracts away the asset specific code, like asset file-path handling
and local asset data-block handling.

Main use-case for this is applying assets as presets that are based on
data-blocks, like poses. Such preset assets are an important part of the
asset system design, so such an abstraction will likely find more usage
in the future.

UI/Assets: Initial Asset View UI template

The asset view UI template is a mini-version of the Asset Browser that
can be placed in regular layouts, regions or popups. At this point it's
made specifically for placement in vertical layouts, it can be made more
flexible in the future.
Generally the way this is implemented will likely change a lot still as
the asset system evolves.

The Pose Library add-on will use the asset view to display pose
libraries in the 3D View sidebar.

References:
* https://developer.blender.org/T86139
* https://code.blender.org/2021/06/asset-browser-project-update/#what-are-we-building
* https://code.blender.org/2021/05/pose-library-v2-0/#use-from-3d-viewport

Notes:
* Important limitation: Due to the early & WIP implementation of the
asset list, all asset views showing the same library will show the
same assets. That is despite the ID type filter option the template
provides. The first asset view created will determine what's visible.
Of course this should be made to work eventually.
* The template supports passing an activate and a drag operator name.
The former is called when an asset is clicked on (e.g. to apply the
asset) the latter when dragging (e.g. to .blend a pose asset). If no
drag operator is set, regular asset drag & drop will be executed.
* The template returns the properties for both operators (see example
below).
* The argument list for using the template is quite long, but we can't
avoid that currently. The UI list design requires that we pass a
number of RNA or custom properties to work with, that for the Pose
Libraries should be registered at the Pose Library add-on level, not
in core Blender.
* Idea is that Python scripts or add-ons that want to use the asset view
can register custom properties, to hold data like the list of assets,
and the active asset index. Maybe that will change in future and we
can manage these internally.

As an example, the pose library add-on uses it like this:
```
activate_op_props, drag_op_props = layout.template_asset_view(
"pose_assets",
workspace,
"active_asset_library",
wm,
"pose_assets",
workspace,
"active_pose_asset_index",
filter_id_types={"filter_action"},
activate_operator="poselib.apply_pose_asset",
drag_operator="poselib.blend_pose_asset",
)
drag_op_props.release_confirm = True
drag_op_props.flipped = wm.poselib_flipped
activate_op_props.flipped = wm.poselib_flipped
```

Assets: AssetHandle type as temporary design to reference assets

With temporary I mean that this is not intended to be part of the
eventual asset system design. For that we are planning to have an
`AssetRepresentation` instead, see T87235. Once the `AssetList` is
implemented (see T88184), that would be the owner of the asset
representations.

However for the upcoming asset system, asset browser, asset view and
pose library commits we need some kind of asset handle to pass around.
That is what this commit introduces.
Idea is a handle to wrap the `FileDirEntry` representing the asset, and
an API to access its data (currently very small, will be extended in
further commits). So the fact that an asset is currently a file
internally is abstracted away. However: We have to expose it as file in
the Python API, because we can't return the asset-handle directly there,
for reasons explained in the code. So the active asset file is exposed
as `bpy.context.asset_file_handle`.