Move `eUndoStepDir` to `BKE_undo_system.h` and use its values
everywhere.
Note that this also introduce the `STEP_INVALID` value in that enum.
Finally, kept the matching struct members in some lower-level readfile
code as an `int` to avoid having to include `BKE_undo_system.h` in a lot
of unrelated files.
Note that this is fairly fragile still, especially in cases like paint
cureve undo, which actually does not use context in most cases (and can
be called with a NULL context), but do need it in one case. This will
need a proper rework at some point.
Rename it to mark it is only for `encode` callbacks, fix `encode`
callback of text undo to early fail in case it gets a NULL context, add
an assert to `BKE_undosys_step_push_with_type` that context is not NULL
when undotype requires a valid one.
Note that in practice this should not change anything, currently it
seems that we always get a valid context in
`BKE_undosys_step_push_with_type`?
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This is often invalid, outdated or misleading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.
- 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
