ID-Remap - Step one: core work (cleanup and rework of generic ID datablock handling).

This commit changes a lot of how IDs are handled internally, especially the unlinking/freeing
processes. So far, this was very fuzy, to summarize cleanly deleting or replacing a datablock
was pretty much impossible, except for a few special cases.

Also, unlinking was handled by each datatype, in a rather messy and prone-to-errors way (quite
a few ID usages were missed or wrongly handled that way).

One of the main goal of id-remap branch was to cleanup this, and fatorize ID links handling
by using library_query utils to allow generic handling of those, which is now the case
(now, generic ID links handling is only "knwon" from readfile.c and library_query.c).

This commit also adds backends to allow live replacement and deletion of datablocks in Blender
(so-called 'remapping' process, where we replace all usages of a given ID pointer by a new one,
or NULL one in case of unlinking).

This will allow nice new features, like ability to easily reload or relocate libraries, real immediate
deletion of datablocks in blender, replacement of one datablock by another, etc.
Some of those are for next commits.

A word of warning: this commit is highly risky, because it affects potentially a lot in Blender core.
Though it was tested rather deeply, being totally impossible to check all possible ID usage cases,
it's likely there are some remaining issues and bugs in new code... Please report them! ;)

Review task: D2027 (https://developer.blender.org/D2027).
Reviewed by campbellbarton, thanks a bunch.

1 files changed, 10 insertions, 8 deletions

diff --git a/source/blender/blenkernel/intern/anim_sys.c b/source/blender/blenkernel/intern/anim_sys.c
index 99aae6239e8..91b33f3efd3 100644
--- a/source/blender/blenkernel/intern/anim_sys.c
+++ b/source/blender/blenkernel/intern/anim_sys.c
@@ -216,7 +216,7 @@ bool BKE_animdata_set_action(ReportList *reports, ID *id, bAction *act)
 /* Freeing -------------------------------------------- */
 
 /* Free AnimData used by the nominated ID-block, and clear ID-block's AnimData pointer */
-void BKE_animdata_free(ID *id)
+void BKE_animdata_free(ID *id, const bool do_id_user)
 {
 	/* Only some ID-blocks have this info for now, so we cast the 
 	 * types that do to be of type IdAdtTemplate
@@ -227,12 +227,14 @@ void BKE_animdata_free(ID *id)
 		
 		/* check if there's any AnimData to start with */
 		if (adt) {
-			/* unlink action (don't free, as it's in its own list) */
-			if (adt->action)
-				id_us_min(&adt->action->id);
-			/* same goes for the temporarily displaced action */
-			if (adt->tmpact)
-				id_us_min(&adt->tmpact->id);
+			if (do_id_user) {
+				/* unlink action (don't free, as it's in its own list) */
+				if (adt->action)
+					id_us_min(&adt->action->id);
+				/* same goes for the temporarily displaced action */
+				if (adt->tmpact)
+					id_us_min(&adt->tmpact->id);
+			}
 				
 			/* free nla data */
 			free_nladata(&adt->nla_tracks);
@@ -292,7 +294,7 @@ bool BKE_animdata_copy_id(ID *id_to, ID *id_from, const bool do_action)
 	if ((id_to && id_from) && (GS(id_to->name) != GS(id_from->name)))
 		return false;
 
-	BKE_animdata_free(id_to);
+	BKE_animdata_free(id_to, true);
 
 	adt = BKE_animdata_from_id(id_from);
 	if (adt) {