UI: Internal support for custom UI list item drag & activate operators

For pose libraries, we need to be able to apply a pose whenever
activating (clicking) an item in the Pose Library asset view and blend
it by dragging (press & move). And since we want to allow Python scripts
to define what happens at least when activating an asset (so they can
define for example a custom "Apply" operator for preset assets), it
makes sense to just let them pass an operator name to the asset view
template. The template will be introduced in a following commit.

1 files changed, 11 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_screen_types.h b/source/blender/makesdna/DNA_screen_types.h
index 79eca09b80a..7032bc23b2c 100644
--- a/source/blender/makesdna/DNA_screen_types.h
+++ b/source/blender/makesdna/DNA_screen_types.h
@@ -287,6 +287,11 @@ typedef struct uiListDyn {
   int *items_filter_flags;
   /** Org_idx -> new_idx, items_len length. */
   int *items_filter_neworder;
+
+  struct wmOperatorType *custom_drag_optype;
+  struct PointerRNA *custom_drag_opptr;
+  struct wmOperatorType *custom_activate_optype;
+  struct PointerRNA *custom_activate_opptr;
 } uiListDyn;
 
 typedef struct uiList { /* some list UI data need to be saved in file */
@@ -313,6 +318,12 @@ typedef struct uiList { /* some list UI data need to be saved in file */
   int filter_flag;
   int filter_sort_flag;
 
+  /** Operator executed when activating an item. */
+  const char *custom_activate_opname;
+  /** Operator executed when dragging an item (item gets activated too, without running
+   * custom_activate_opname above). */
+  const char *custom_drag_opname;
+
   /* Custom sub-classes properties. */
   IDProperty *properties;