Undo: unified undo system w/ linear history

- 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

1 files changed, 8 insertions, 9 deletions

diff --git a/source/blender/editors/include/ED_util.h b/source/blender/editors/include/ED_util.h
index 60c4b3593aa..5a373cebac1 100644
--- a/source/blender/editors/include/ED_util.h
+++ b/source/blender/editors/include/ED_util.h
@@ -35,6 +35,9 @@ struct bContext;
 struct SpaceLink;
 struct wmOperator;
 struct wmOperatorType;
+struct UndoStack;
+struct ScrArea;
+struct PackedFile;
 
 /* ed_util.c */
 
@@ -70,16 +73,12 @@ void    ED_undo_operator_repeat_cb_evt(struct bContext *C, void *arg_op, int arg
 
 bool    ED_undo_is_valid(const struct bContext *C, const char *undoname);
 
-/* undo_editmode.c */
-void undo_editmode_push(struct bContext *C, const char *name, 
-                        void * (*getdata)(struct bContext *C),
-                        void (*freedata)(void *),
-                        void (*to_editmode)(void *, void *, void *),
-                        void *(*from_editmode)(void *, void *),
-                        int (*validate_undo)(void *, void *));
+/* undo_system_types.c */
+void ED_undosys_type_init(void);
+void ED_undosys_type_free(void);
 
-
-void    undo_editmode_clear(void);
+/* memfile_undo.c */
+struct MemFile *ED_undosys_stack_memfile_get_active(struct UndoStack *ustack);
 
 /* ************** XXX OLD CRUFT WARNING ************* */