Cleanup/refactor: Undosys: Get rid of the magic values for undo direction.

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.

1 files changed, 3 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_blender_undo.h b/source/blender/blenkernel/BKE_blender_undo.h
index e5ce91df3fb..1febe75b6f2 100644
--- a/source/blender/blenkernel/BKE_blender_undo.h
+++ b/source/blender/blenkernel/BKE_blender_undo.h
@@ -27,12 +27,14 @@ struct Main;
 struct MemFileUndoData;
 struct bContext;
 
+enum eUndoStepDir;
+
 #define BKE_UNDO_STR_MAX 64
 
 struct MemFileUndoData *BKE_memfile_undo_encode(struct Main *bmain,
                                                 struct MemFileUndoData *mfu_prev);
 bool BKE_memfile_undo_decode(struct MemFileUndoData *mfu,
-                             const int undo_direction,
+                             const enum eUndoStepDir undo_direction,
                              const bool use_old_bmain_data,
                              struct bContext *C);
 void BKE_memfile_undo_free(struct MemFileUndoData *mfu);