This complicated handling of undo steps in a generic way
especially switching between undo systems that stored data to ones
that accumulated changes.
Now each undo system must treat it's steps as check-point,
internally it can apply/rewind changes.
This commit also fixes projection paint where the object mode wasn't
following the undo steps.
BF-admins agree to remove header information that isn't useful,
to reduce noise.
- BEGIN/END license blocks
Developers should add non license comments as separate comment blocks.
No need for separator text.
- Contributors
This is often invalid, outdated or misleading
especially when splitting files.
It's more useful to git-blame to find out who has developed the code.
See P901 for script to perform these edits.
Add the ability for undo steps to request memfile undo step added after
them, useful for mode switching, where we need the data to exist for
undo to enter the mode.
Currently names are used for edit-mode undo-steps,
any changes to Main ID names cause lookup failure (crashing).
This commit ensures any undo steps that use ID lookups have the same
mem-file undo state loaded that was used to encode the steps.
Renaming also has an undo push added (last commit).
For grouped undo we should not skip the undo push, rather replace the
previous undo push. This way undo goes back to the state after the last
operation in the group.
- 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
