Performance: Draw play head as an overlay

When playing back animations a playhead is updated in all the animation editors.
The drawing of the playhead is part of the drawing of the main region
`RGN_TYPE_WINDOW` that redraws the whole region.

This change will draw the play head and window scrollers when updating the
screen. This affects the Action editor, Timeline, Graph editor, NLA editor and
Sequence editor. There is noticeable speedup when using complex animation files.

Spring 02_020_A.anim.blend fps went from 11.8 to 12.5 when showing a timeline
and a action editor on a Ryzen 1700.

* When playing back animation the markers don't jump up/down when near the
  frame. This could be added back.

Reviewed By: Brecht van Lommel

Differential Revision: https://developer.blender.org/D8066

1 files changed, 12 insertions, 3 deletions

diff --git a/source/blender/editors/space_nla/space_nla.c b/source/blender/editors/space_nla/space_nla.c
index aeb5c30c809..b09536e0621 100644
--- a/source/blender/editors/space_nla/space_nla.c
+++ b/source/blender/editors/space_nla/space_nla.c
@@ -259,13 +259,10 @@ static void nla_main_region_draw(const bContext *C, ARegion *region)
     UI_view2d_text_cache_draw(region);
   }
 
-  UI_view2d_view_ortho(v2d);
-
   /* current frame */
   if (snla->flag & SNLA_DRAWTIME) {
     cfra_flag |= DRAWCFRA_UNIT_SECONDS;
   }
-  ANIM_draw_cfra(C, v2d, cfra_flag);
 
   /* markers */
   UI_view2d_view_orthoSpecial(region, v2d, 1);
@@ -286,6 +283,17 @@ static void nla_main_region_draw(const bContext *C, ARegion *region)
   UI_view2d_view_restore(C);
 
   ED_time_scrub_draw(region, scene, snla->flag & SNLA_DRAWTIME, true);
+}
+
+static void nla_main_region_draw_overlay(const bContext *C, ARegion *region)
+{
+  /* draw entirely, view changes should be handled here */
+  const SpaceNla *snla = CTX_wm_space_nla(C);
+  const Scene *scene = CTX_data_scene(C);
+  View2D *v2d = &region->v2d;
+
+  /* scrubbing region */
+  ED_time_scrub_draw_current_frame(region, scene, snla->flag & SNLA_DRAWTIME, true);
 
   /* scrollers */
   UI_view2d_scrollers_draw(v2d, NULL);
@@ -614,6 +622,7 @@ void ED_spacetype_nla(void)
   art->regionid = RGN_TYPE_WINDOW;
   art->init = nla_main_region_init;
   art->draw = nla_main_region_draw;
+  art->draw_overlay = nla_main_region_draw_overlay;
   art->listener = nla_main_region_listener;
   art->message_subscribe = nla_main_region_message_subscribe;
   art->keymapflag = ED_KEYMAP_VIEW2D | ED_KEYMAP_ANIMATION | ED_KEYMAP_FRAMES;