UI: better support for dynamically sized regions in topbar.

Dynamically sized regions in the topbar were flickering due to only updating
their size after redraws. Now there is an optional layout() callback for
all regions in an area to do UI layout first, then refresh the region layout,
and then do the actual drawing for each region.

Task T54753

1 files changed, 4 insertions, 12 deletions

diff --git a/source/blender/editors/space_topbar/space_topbar.c b/source/blender/editors/space_topbar/space_topbar.c
index f2824b3bf70..fc76fd9c638 100644
--- a/source/blender/editors/space_topbar/space_topbar.c
+++ b/source/blender/editors/space_topbar/space_topbar.c
@@ -132,11 +132,6 @@ static void topbar_main_region_init(wmWindowManager *wm, ARegion *region)
 	WM_event_add_keymap_handler(&region->handlers, keymap);
 }
 
-static void topbar_main_region_draw(const bContext *C, ARegion *region)
-{
-	ED_region_header(C, region);
-}
-
 static void topbar_operatortypes(void)
 {
 
@@ -156,11 +151,6 @@ static void topbar_header_region_init(wmWindowManager *UNUSED(wm), ARegion *ar)
 	ED_region_header_init(ar);
 }
 
-static void topbar_header_region_draw(const bContext *C, ARegion *ar)
-{
-	ED_region_header(C, ar);
-}
-
 static void topbar_main_region_listener(bScreen *UNUSED(sc), ScrArea *UNUSED(sa), ARegion *ar,
                                         wmNotifier *wmn, const Scene *UNUSED(scene))
 {
@@ -263,7 +253,8 @@ void ED_spacetype_topbar(void)
 	art = MEM_callocN(sizeof(ARegionType), "spacetype topbar main region");
 	art->regionid = RGN_TYPE_WINDOW;
 	art->init = topbar_main_region_init;
-	art->draw = topbar_main_region_draw;
+	art->layout = ED_region_header_layout;
+	art->draw = ED_region_header_draw;
 	art->listener = topbar_main_region_listener;
 	art->prefsizex = UI_UNIT_X * 5; /* Mainly to avoid glitches */
 	art->keymapflag = ED_KEYMAP_UI | ED_KEYMAP_VIEW2D | ED_KEYMAP_HEADER;
@@ -279,7 +270,8 @@ void ED_spacetype_topbar(void)
 	art->listener = topbar_header_listener;
 	art->message_subscribe = topbar_header_region_message_subscribe;
 	art->init = topbar_header_region_init;
-	art->draw = topbar_header_region_draw;
+	art->layout = ED_region_header_layout;
+	art->draw = ED_region_header_draw;
 
 	BLI_addhead(&st->regiontypes, art);