A tree-view item's drop controller can now return a message for the user
explaining why dropping isn't possible with the dropped data. This is then
displayed in red text next to the cursor.
This isn't actually used yet, the follow up commit will do that.
No functional changes.
This commit adds 3 callbacks for `wmDropBox` which allow custom drawing
without affecting the internal dropbox API.
Differential Revision: https://developer.blender.org/D12948
Introduces a dropping-controller API for the tree-view items,
`AbstractTreeViewItemDropController`. This reduces responsibilities of the main
tree-view item classes, which are already getting quite big. As I expect even
more functionality to be needed for it (e.g. drag support), it's better to
start introducing such controller types already.
This change simplifies the parameter list for these functions
and reduces the chance of typos mixing up array indices.
Reviewed By: campbellbarton
Ref D12950
Use arrays for wmEvent coordinates, this quiets warnings with GCC11.
- `x, y` -> `xy`.
- `prevx, prevy` -> `prev_xy`.
- `prevclickx, prevclicky` -> `prev_click_xy`.
There is still some cleanup such as using `copy_v2_v2_int()`,
this can be done separately.
Reviewed By: campbellbarton, Severin
Ref D12901
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
