VSE strip thumbnails

Draw thumbnails as strip overlay. This works for movie and image strips.
To draw thumbnails, this overlay has to be enabled and strips must be
tall enough.

The thumbnails are loaded from source file using separate thread and
stored in cache.

Drawing code uses only images stored in cache, and if any is missing,
background rendering job is started. If job can not render thumbnail,
to prevent endless loop of creating job for missing image it sets
`SEQ_FLAG_SKIP_THUMBNAILS` bit of `Sequence` flag.

To prevent visual glitches during timeline panning and zooming, `View2D`
flag `V2D_IS_NAVIGATING` is implemented. If bit is set, drawing code
will look for set of evenly distributed thumbnails that should be
guaranteed to exist and also set of previously displayed thumbnails.
Due to volatile nature of cache these thumbnails can be missing anyway,
in which case no new thumbnails will be drawn for particular strip.

Cache capacity is limited to 5000 thumbnails and performs cleanup of
non visible images when limit is reached.

ref T89143

Reviewed By: ISS

Differential Revision: https://developer.blender.org/D12266

1 files changed, 16 insertions, 2 deletions

diff --git a/source/blender/editors/interface/view2d_ops.c b/source/blender/editors/interface/view2d_ops.c
index 1fd1b6c984d..8fab34d486c 100644
--- a/source/blender/editors/interface/view2d_ops.c
+++ b/source/blender/editors/interface/view2d_ops.c
@@ -147,6 +147,8 @@ static void view_pan_init(bContext *C, wmOperator *op)
   const float winy = (float)(BLI_rcti_size_y(&vpd->region->winrct) + 1);
   vpd->facx = (BLI_rctf_size_x(&vpd->v2d->cur)) / winx;
   vpd->facy = (BLI_rctf_size_y(&vpd->v2d->cur)) / winy;
+
+  vpd->v2d->flag |= V2D_IS_NAVIGATING;
 }
 
 /* apply transform to view (i.e. adjust 'cur' rect) */
@@ -190,6 +192,8 @@ static void view_pan_apply(bContext *C, wmOperator *op)
 /* Cleanup temp custom-data. */
 static void view_pan_exit(wmOperator *op)
 {
+  v2dViewPanData *vpd = op->customdata;
+  vpd->v2d->flag &= ~V2D_IS_NAVIGATING;
   MEM_SAFE_FREE(op->customdata);
 }
 
@@ -305,7 +309,7 @@ static int view_pan_modal(bContext *C, wmOperator *op, const wmEvent *event)
   return OPERATOR_RUNNING_MODAL;
 }
 
-static void view_pan_cancel(bContext *UNUSED(C), wmOperator *op)
+static void view_pan_cancel(bContext *C, wmOperator *op)
 {
   view_pan_exit(op);
 }
@@ -358,6 +362,7 @@ static int view_edge_pan_modal(bContext *C, wmOperator *op, const wmEvent *event
   View2DEdgePanData *vpd = op->customdata;
 
   if (event->val == KM_RELEASE || event->type == EVT_ESCKEY) {
+    vpd->v2d->flag &= ~V2D_IS_NAVIGATING;
     MEM_SAFE_FREE(op->customdata);
     return (OPERATOR_FINISHED | OPERATOR_PASS_THROUGH);
   }
@@ -371,6 +376,8 @@ static int view_edge_pan_modal(bContext *C, wmOperator *op, const wmEvent *event
 
 static void view_edge_pan_cancel(bContext *UNUSED(C), wmOperator *op)
 {
+  v2dViewPanData *vpd = op->customdata;
+  vpd->v2d->flag &= ~V2D_IS_NAVIGATING;
   MEM_SAFE_FREE(op->customdata);
 }
 
@@ -680,6 +687,8 @@ static void view_zoomdrag_init(bContext *C, wmOperator *op)
   vzd->v2d = &vzd->region->v2d;
   /* False by default. Interactive callbacks (ie invoke()) can set it to true. */
   vzd->zoom_to_mouse_pos = false;
+
+  vzd->v2d->flag |= V2D_IS_NAVIGATING;
 }
 
 /* apply transform to view (i.e. adjust 'cur' rect) */
@@ -809,7 +818,8 @@ static void view_zoomstep_apply(bContext *C, wmOperator *op)
 static void view_zoomstep_exit(wmOperator *op)
 {
   UI_view2d_zoom_cache_reset();
-
+  v2dViewZoomData *vzd = op->customdata;
+  vzd->v2d->flag &= ~V2D_IS_NAVIGATING;
   MEM_SAFE_FREE(op->customdata);
 }
 
@@ -1041,6 +1051,7 @@ static void view_zoomdrag_exit(bContext *C, wmOperator *op)
 
   if (op->customdata) {
     v2dViewZoomData *vzd = op->customdata;
+    vzd->v2d->flag &= ~V2D_IS_NAVIGATING;
 
     if (vzd->timer) {
       WM_event_remove_timer(CTX_wm_manager(C), CTX_wm_window(C), vzd->timer);
@@ -1911,6 +1922,8 @@ static void scroller_activate_init(bContext *C,
     vsm->scrollbar_orig = ((scrollers.vert_max + scrollers.vert_min) / 2) + region->winrct.ymin;
   }
 
+  vsm->v2d->flag |= V2D_IS_NAVIGATING;
+
   ED_region_tag_redraw_no_rebuild(region);
 }
 
@@ -1921,6 +1934,7 @@ static void scroller_activate_exit(bContext *C, wmOperator *op)
     v2dScrollerMove *vsm = op->customdata;
 
     vsm->v2d->scroll_ui &= ~(V2D_SCROLL_H_ACTIVE | V2D_SCROLL_V_ACTIVE);
+    vsm->v2d->flag &= ~V2D_IS_NAVIGATING;
 
     MEM_freeN(op->customdata);
     op->customdata = NULL;