UI Drag Drop: allow customizable drawing

No functional changes.

This commit adds 3 callbacks for `wmDropBox` which allow custom drawing
without affecting the internal dropbox API.

Differential Revision: https://developer.blender.org/D12948

1 files changed, 18 insertions, 3 deletions

diff --git a/source/blender/windowmanager/WM_types.h b/source/blender/windowmanager/WM_types.h
index f4595869baf..bbfc9d53e44 100644
--- a/source/blender/windowmanager/WM_types.h
+++ b/source/blender/windowmanager/WM_types.h
@@ -1020,7 +1020,7 @@ typedef struct wmDragAssetListItem {
 
 typedef char *(*WMDropboxTooltipFunc)(struct bContext *,
                                       struct wmDrag *,
-                                      const struct wmEvent *event,
+                                      const int xy[2],
                                       struct wmDropBox *drop);
 
 typedef struct wmDrag {
@@ -1038,8 +1038,11 @@ typedef struct wmDrag {
   float scale;
   int sx, sy;
 
-  /** If filled, draws operator tooltip/operator name. */
-  char tooltip[200];
+  /** Informs which dropbox is activated with the drag item.
+   * When this value changes, the #draw_activate and #draw_deactivate dropbox callbacks are
+   * triggered.
+   */
+  struct wmDropBox *active_dropbox;
   unsigned int flags;
 
   /** List of wmDragIDs, all are guaranteed to have the same ID type. */
@@ -1067,6 +1070,18 @@ typedef struct wmDropBox {
    */
   void (*cancel)(struct Main *, struct wmDrag *, struct wmDropBox *);
 
+  /** Override the default drawing function. */
+  void (*draw)(struct bContext *, struct wmWindow *, struct wmDrag *, const int *);
+
+  /** Called when pool returns true the first time. */
+  void (*draw_activate)(struct wmDropBox *, struct wmDrag *drag);
+
+  /** Called when pool returns false the first time or when the drag event ends. */
+  void (*draw_deactivate)(struct wmDropBox *, struct wmDrag *drag);
+
+  /** Custom data for drawing. */
+  void *draw_data;
+
   /** Custom tooltip shown during dragging. */
   WMDropboxTooltipFunc tooltip;