- Use a single undo history for all operations.
- UndoType's are registered and poll the context to check if they
should be used when performing an undo push.
- Mode switching is used to ensure the state is correct before
undo data is restored.
- Some undo types accumulate changes (image & text editing)
others store the state multiple times (with de-duplication).
This is supported by checking UndoStack.mode `ACCUMULATE` / `STORE`.
- Each undo step stores ID datablocks they use with utilities to help
manage restoring correct ID's.
Needed since global undo is now mixed with other modes undo.
- Currently performs each undo step when going up/down history
Previously this wasn't done, making history fail in some cases.
This can be optimized to skip some combinations of undo steps.
grease-pencil is an exception which has not been updated
since it integrates undo into the draw-session.
See D3113
This option makes an operator to not push a task to the undo stack if the previous stored elemen is the same operator or part of the same undo group.
The main usage is for animation, so you can change frames to inspect the
poses, and revert the previous pose without having to roll back tons of
"change frame" operator, or even see the undo stack full.
This complements rB13ee9b8e
Design with help by Sergey Sharybin.
Reviewers: sergey, mont29
Reviewed By: mont29, sergey
Subscribers: pyc0d3r, hjalti, Severin, lowercase, brecht, monio, aligorith, hadrien, jbakker
Differential Revision: https://developer.blender.org/D2330
