Python API: add methods for reordering constraints.

Order matters for constraints, but there was no way to change it.
The API follows other collections like idprops and node sockets.

2 files changed, 22 insertions, 0 deletions

diff --git a/source/blender/blenlib/BLI_listbase.h b/source/blender/blenlib/BLI_listbase.h
index b8b62dd3451..b027acb88da 100644
--- a/source/blender/blenlib/BLI_listbase.h
+++ b/source/blender/blenlib/BLI_listbase.h
@@ -93,6 +93,7 @@ void BLI_listbase_sort_r(ListBase *listbase,
                          int (*cmp)(void *, const void *, const void *),
                          void *thunk) ATTR_NONNULL(1, 2);
 bool BLI_listbase_link_move(ListBase *listbase, void *vlink, int step) ATTR_NONNULL();
+bool BLI_listbase_move_index(ListBase *listbase, int from, int to) ATTR_NONNULL();
 void BLI_freelist(struct ListBase *listbase) ATTR_NONNULL(1);
 int BLI_listbase_count_at_most(const struct ListBase *listbase,
                                const int count_max) ATTR_WARN_UNUSED_RESULT ATTR_NONNULL(1);
diff --git a/source/blender/blenlib/intern/listbase.c b/source/blender/blenlib/intern/listbase.c
index 31d372945c6..631978f60fe 100644
--- a/source/blender/blenlib/intern/listbase.c
+++ b/source/blender/blenlib/intern/listbase.c
@@ -504,6 +504,27 @@ bool BLI_listbase_link_move(ListBase *listbase, void *vlink, int step)
 }
 
 /**
+ * Move the link at the index \a from to the position at index \a to.
+ *
+ * @return If the move was successful.
+ */
+bool BLI_listbase_move_index(ListBase *listbase, int from, int to)
+{
+  if (from == to) {
+    return false;
+  }
+
+  /* Find the link to move. */
+  void *link = BLI_findlink(listbase, from);
+
+  if (!link) {
+    return false;
+  }
+
+  return BLI_listbase_link_move(listbase, link, to - from);
+}
+
+/**
  * Removes and disposes of the entire contents of listbase using direct free(3).
  */
 void BLI_freelist(ListBase *listbase)