Fix T78959: Show current frame indicator when interface is locked

When the playhead drawing moved to an overlay, a check was added to keep
it from drawing with a locked interface. This is necessary for some overlays,
but not this one, so this removes the check, making it the responsibility of
the editor.

A context function is added to make that check easier in the future.

Differential Revision: https://developer.blender.org/D8313

4 files changed, 14 insertions, 7 deletions

diff --git a/source/blender/blenkernel/BKE_context.h b/source/blender/blenkernel/BKE_context.h
index 70ca29d5795..7544789d864 100644
--- a/source/blender/blenkernel/BKE_context.h
+++ b/source/blender/blenkernel/BKE_context.h
@@ -312,6 +312,8 @@ int CTX_data_visible_gpencil_layers(const bContext *C, ListBase *list);
 int CTX_data_editable_gpencil_layers(const bContext *C, ListBase *list);
 int CTX_data_editable_gpencil_strokes(const bContext *C, ListBase *list);
 
+bool CTX_wm_interface_locked(const bContext *C);
+
 /* Gets pointer to the dependency graph.
  * If it doesn't exist yet, it will be allocated.
  *
diff --git a/source/blender/blenkernel/BKE_screen.h b/source/blender/blenkernel/BKE_screen.h
index 91f241018ec..13716ddb5c6 100644
--- a/source/blender/blenkernel/BKE_screen.h
+++ b/source/blender/blenkernel/BKE_screen.h
@@ -142,7 +142,13 @@ typedef struct ARegionType {
   void (*exit)(struct wmWindowManager *wm, struct ARegion *region);
   /* draw entirely, view changes should be handled here */
   void (*draw)(const struct bContext *C, struct ARegion *region);
-  /* Handler to draw overlays. This handler is called every draw loop. */
+  /**
+   * Handler to draw overlays. This handler is called every draw loop.
+   *
+   * \note Some editors should return early if the interface is locked
+   * (check with #CTX_wm_interface_locked) to avoid accessing scene data
+   * that another thread may be modifying
+   */
   void (*draw_overlay)(const struct bContext *C, struct ARegion *region);
   /* optional, compute button layout before drawing for dynamic size */
   void (*layout)(const struct bContext *C, struct ARegion *region);
diff --git a/source/blender/blenkernel/intern/context.c b/source/blender/blenkernel/intern/context.c
index 8de12139306..30f021b0e81 100644
--- a/source/blender/blenkernel/intern/context.c
+++ b/source/blender/blenkernel/intern/context.c
@@ -694,6 +694,11 @@ wmWindowManager *CTX_wm_manager(const bContext *C)
   return C->wm.manager;
 }
 
+bool CTX_wm_interface_locked(const bContext *C)
+{
+  return (bool)C->wm.manager->is_interface_locked;
+}
+
 wmWindow *CTX_wm_window(const bContext *C)
 {
   return ctx_wm_python_context_get(C, "window", &RNA_Window, C->wm.window);
diff --git a/source/blender/windowmanager/intern/wm_draw.c b/source/blender/windowmanager/intern/wm_draw.c
index 4cc30d65fdb..75580824d9c 100644
--- a/source/blender/windowmanager/intern/wm_draw.c
+++ b/source/blender/windowmanager/intern/wm_draw.c
@@ -138,12 +138,6 @@ static void wm_region_draw_overlay(bContext *C, ScrArea *area, ARegion *region)
   wmWindowManager *wm = CTX_wm_manager(C);
   wmWindow *win = CTX_wm_window(C);
 
-  /* Don't draw overlay with locked interface. Drawing could access scene data that another thread
-   * may be modifying. */
-  if (wm->is_interface_locked) {
-    return;
-  }
-
   wmViewport(&region->winrct);
   UI_SetTheme(area->spacetype, region->regiontype);
   region->type->draw_overlay(C, region);