VSE: prefetching

When enabled prefetching(preview panel>view settings), a pernament running job
is created, that will render frames in the background until the cache is full.
If the cache is not filled fast enough, prefetch job suspends itself
at the last moment and will wait until it has chance to "catch up".
Effectively this will decouple rendering to separate thread, so rendering
itself is a bit faster.
Cache recycling behavior will be changed to "free furthest frame to the left
of playhead if possible, otherwise rightmost frame".

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D5386

1 files changed, 12 insertions, 0 deletions

diff --git a/source/blender/editors/space_sequencer/sequencer_draw.c b/source/blender/editors/space_sequencer/sequencer_draw.c
index b15acb12d00..bf555e8fe09 100644
--- a/source/blender/editors/space_sequencer/sequencer_draw.c
+++ b/source/blender/editors/space_sequencer/sequencer_draw.c
@@ -72,6 +72,7 @@
 #include "UI_view2d.h"
 
 #include "WM_api.h"
+#include "WM_types.h"
 
 #include "MEM_guardedalloc.h"
 
@@ -1223,6 +1224,14 @@ void sequencer_draw_maskedit(const bContext *C, Scene *scene, ARegion *ar, Space
 }
 #endif
 
+/* Force redraw, when prefetching and using cache view. */
+static void seq_prefetch_wm_notify(const bContext *C, Scene *scene)
+{
+  if (BKE_sequencer_prefetch_need_redraw(CTX_data_main(C), scene)) {
+    WM_event_add_notifier(C, NC_SCENE | ND_SEQUENCER, NULL);
+  }
+}
+
 static void *sequencer_OCIO_transform_ibuf(
     const bContext *C, ImBuf *ibuf, bool *glsl_used, int *format, int *type)
 {
@@ -1612,6 +1621,7 @@ void sequencer_draw_preview(const bContext *C,
   }
 
   UI_view2d_view_restore(C);
+  seq_prefetch_wm_notify(C, scene);
 }
 
 #if 0
@@ -2004,6 +2014,8 @@ void draw_timeline_seq(const bContext *C, ARegion *ar)
   short cfra_flag = 0;
   float col[3];
 
+  seq_prefetch_wm_notify(C, scene);
+
   /* clear and setup matrix */
   UI_GetThemeColor3fv(TH_BACK, col);
   if (ed && ed->metastack.first) {