Asset Browser: Support dragging catalogs to move them in the hierarchy

Uses the additions to the UI tree-view API from the previous commit to
enable drag & drop of asset catalogs. The catalogs will be moved in the
tree including children.
A remaining issue is that a catalog with children will always be
collapsed when dropping. I need to find a way to fix that in the
tree-view API.

There are a few improvements I can think of for the tree-item drag &
drop support, but time for these is too short. These can be done as
normal cleanups at some point.

1 files changed, 10 insertions, 0 deletions

diff --git a/source/blender/windowmanager/intern/wm_dragdrop.c b/source/blender/windowmanager/intern/wm_dragdrop.c
index 50ac046ed54..df6d3d5e9e7 100644
--- a/source/blender/windowmanager/intern/wm_dragdrop.c
+++ b/source/blender/windowmanager/intern/wm_dragdrop.c
@@ -181,6 +181,7 @@ wmDrag *WM_event_start_drag(
       }
       break;
     case WM_DRAG_ASSET:
+    case WM_DRAG_ASSET_CATALOG:
       /* Move ownership of poin to wmDrag. */
       drag->poin = poin;
       drag->flags |= WM_DRAG_FREE_DATA;
@@ -649,6 +650,15 @@ void WM_drag_free_imported_drag_ID(struct Main *bmain, wmDrag *drag, wmDropBox *
   }
 }
 
+wmDragAssetCatalog *WM_drag_get_asset_catalog_data(const wmDrag *drag)
+{
+  if (drag->type != WM_DRAG_ASSET_CATALOG) {
+    return NULL;
+  }
+
+  return drag->poin;
+}
+
 /**
  * \note: Does not store \a asset in any way, so it's fine to pass a temporary.
  */