VSE: Move remove gaps operator logic to module code

Logic was broken into finding gaps and ofsetting strips.
Functions were modified so they work on explicitly defined seqbase,
so they can be used as python API functions.

Functional changes:
 - Improve performance by calculating gap length and offseting strips
   at once. Previously strips were offset by one frame.
 - Calculate gap from start frame. Previously gap was considered only
   inbetween strips.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D9730

1 files changed, 84 insertions, 0 deletions

diff --git a/source/blender/sequencer/intern/strip_time.c b/source/blender/sequencer/intern/strip_time.c
index a0ae6d6f16d..015d81cc217 100644
--- a/source/blender/sequencer/intern/strip_time.c
+++ b/source/blender/sequencer/intern/strip_time.c
@@ -351,3 +351,87 @@ float BKE_sequence_get_fps(Scene *scene, Sequence *seq)
   }
   return 0.0f;
 }
+
+/**
+ * Define boundary rectangle of sequencer timeline and fill in rect data
+ *
+ * \param scene: Scene in which strips are located
+ * \param seqbase: ListBase in which strips are located
+ * \param rect: data structure describing rectangle, that will be filled in by this function
+ */
+void SEQ_timeline_boundbox(const Scene *scene, const ListBase *seqbase, rctf *rect)
+{
+  float min[2], max[2];
+  min[0] = scene->r.sfra;
+  max[0] = scene->r.efra + 1;
+  min[1] = 0.0;
+  max[1] = 8.0;
+
+  LISTBASE_FOREACH (Sequence *, seq, seqbase) {
+    if (min[0] > seq->startdisp - 1) {
+      min[0] = seq->startdisp - 1;
+    }
+    if (max[0] < seq->enddisp + 1) {
+      max[0] = seq->enddisp + 1;
+    }
+    if (max[1] < seq->machine + 2) {
+      max[1] = seq->machine + 2;
+    }
+  }
+
+  rect->xmin = min[0];
+  rect->xmax = max[0];
+  rect->ymin = min[1];
+  rect->ymax = max[1];
+}
+
+/**
+ * Find first gap between strips after initial_frame and describe it by filling data of r_gap_info
+ *
+ * \param scene: Scene in which strips are located
+ * \param seqbase: ListBase in which strips are located
+ * \param initial_frame: frame on timeline from where gaps are searched for
+ * \param r_gap_info: data structure describing gap, that will be filled in by this function
+ */
+void seq_time_gap_info_get(const Scene *scene,
+                           ListBase *seqbase,
+                           const int initial_frame,
+                           GapInfo *r_gap_info)
+{
+  rctf rectf;
+  /* Get first and last frame. */
+  SEQ_timeline_boundbox(scene, seqbase, &rectf);
+  const int sfra = (int)rectf.xmin;
+  const int efra = (int)rectf.xmax;
+  int timeline_frame = initial_frame;
+  r_gap_info->gap_exists = false;
+
+  if (SEQ_render_evaluate_frame(seqbase, initial_frame) == 0) {
+    /* Search backward for gap_start_frame. */
+    for (; timeline_frame >= sfra; timeline_frame--) {
+      if (SEQ_render_evaluate_frame(seqbase, timeline_frame) != 0) {
+        break;
+      }
+    }
+    r_gap_info->gap_start_frame = timeline_frame + 1;
+    timeline_frame = initial_frame;
+  }
+  else {
+    /* Search forward for gap_start_frame. */
+    for (; timeline_frame <= efra; timeline_frame++) {
+      if (SEQ_render_evaluate_frame(seqbase, timeline_frame) == 0) {
+        r_gap_info->gap_start_frame = timeline_frame;
+        break;
+      }
+    }
+  }
+  /* Search forward for gap_end_frame. */
+  for (; timeline_frame <= efra; timeline_frame++) {
+    if (SEQ_render_evaluate_frame(seqbase, timeline_frame) != 0) {
+      const int gap_end_frame = timeline_frame;
+      r_gap_info->gap_length = gap_end_frame - r_gap_info->gap_start_frame;
+      r_gap_info->gap_exists = true;
+      break;
+    }
+  }
+}