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, 10 insertions, 1 deletions

diff --git a/source/blender/editors/space_sequencer/sequencer_draw.c b/source/blender/editors/space_sequencer/sequencer_draw.c
index 070ae72d789..fc51438d121 100644
--- a/source/blender/editors/space_sequencer/sequencer_draw.c
+++ b/source/blender/editors/space_sequencer/sequencer_draw.c
@@ -2345,7 +2345,6 @@ void draw_timeline_seq(const bContext *C, ARegion *region)
   ED_region_draw_cb_draw(C, region, REGION_DRAW_POST_VIEW);
   UI_view2d_view_restore(C);
   ED_time_scrub_draw(region, scene, !(sseq->flag & SEQ_DRAWFRAMES), true);
-  UI_view2d_scrollers_draw(v2d, NULL);
 
   /* Draw channel numbers. */
   {
@@ -2355,3 +2354,13 @@ void draw_timeline_seq(const bContext *C, ARegion *region)
     UI_view2d_draw_scale_y__block(region, v2d, &rect, TH_SCROLL_TEXT);
   }
 }
+
+void draw_timeline_seq_display(const bContext *C, ARegion *region)
+{
+  const Scene *scene = CTX_data_scene(C);
+  const SpaceSeq *sseq = CTX_wm_space_seq(C);
+  View2D *v2d = &region->v2d;
+
+  ED_time_scrub_draw_current_frame(region, scene, !(sseq->flag & SEQ_DRAWFRAMES), true);
+  UI_view2d_scrollers_draw(v2d, NULL);
+}