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, 14 insertions, 3 deletions

diff --git a/source/blender/editors/util/ed_util.c b/source/blender/editors/util/ed_util.c
index 57ff8b6db01..03d0b4a8d48 100644
--- a/source/blender/editors/util/ed_util.c
+++ b/source/blender/editors/util/ed_util.c
@@ -58,6 +58,7 @@
 #include "BKE_packedFile.h"
 #include "BKE_paint.h"
 #include "BKE_screen.h"
+#include "BKE_undo_system.h"
 
 #include "ED_armature.h"
 #include "ED_buttons.h"
@@ -89,6 +90,10 @@ void ED_editors_init(bContext *C)
 	Object *ob, *obact = (sce && sce->basact) ? sce->basact->object : NULL;
 	ID *data;
 
+	if (wm->undo_stack == NULL) {
+		wm->undo_stack = BKE_undosys_stack_create();
+	}
+
 	/* This is called during initialization, so we don't want to store any reports */
 	ReportList *reports = CTX_wm_reports(C);
 	int reports_flag_prev = reports->flag & ~RPT_STORE;
@@ -128,9 +133,15 @@ void ED_editors_exit(bContext *C)
 		return;
 	
 	/* frees all editmode undos */
-	undo_editmode_clear();
-	ED_undo_paint_free();
-	
+	if (G.main->wm.first) {
+		wmWindowManager *wm = G.main->wm.first;
+		/* normally we don't check for NULL undo stack, do here since it may run in different context. */
+		if (wm->undo_stack) {
+			BKE_undosys_stack_destroy(wm->undo_stack);
+			wm->undo_stack = NULL;
+		}
+	}
+
 	for (sce = bmain->scene.first; sce; sce = sce->id.next) {
 		if (sce->obedit) {
 			Object *ob = sce->obedit;