Fix T73014: Marker sync does not work correctly if moving strip so it overlaps another strip

Need to also offset markers in BKE_sequence_base_shuffle_time().
Also clarify/correct related comments.

Maniphest Tasks: T73014

Differential Revision: https://developer.blender.org/D6555

source/blender/blenkernel/BKE_sequencer.h

@@ -413,7 +413,10 @@ bool BKE_sequence_base_shuffle_ex(struct ListBase *seqbasep,
 bool BKE_sequence_base_shuffle(struct ListBase *seqbasep,
                                struct Sequence *test,
                                struct Scene *evil_scene);
-bool BKE_sequence_base_shuffle_time(ListBase *seqbasep, struct Scene *evil_scene);
+bool BKE_sequence_base_shuffle_time(ListBase *seqbasep,
+                                    struct Scene *evil_scene,
+                                    ListBase *markers,
+                                    const bool use_sync_markers);
 bool BKE_sequence_base_isolated_sel_check(struct ListBase *seqbase);
 void BKE_sequencer_free_imbuf(struct Scene *scene, struct ListBase *seqbasep, bool for_render);
 struct Sequence *BKE_sequence_dupli_recursive(const struct Scene *scene_src,

source/blender/blenkernel/intern/sequencer.c

@@ -4919,7 +4919,10 @@ static int shuffle_seq_time_offset(Scene *scene, ListBase *seqbasep, char dir)
   return tot_ofs;
 }
 
-bool BKE_sequence_base_shuffle_time(ListBase *seqbasep, Scene *evil_scene)
+bool BKE_sequence_base_shuffle_time(ListBase *seqbasep,
+                                    Scene *evil_scene,
+                                    ListBase *markers,
+                                    const bool use_sync_markers)
 {
   /* note: seq->tmp is used to tag strips to move */
 
@@ -4936,6 +4939,16 @@ bool BKE_sequence_base_shuffle_time(ListBase *seqbasep, Scene *evil_scene)
         seq->flag &= ~SEQ_OVERLAP;
       }
     }
+
+    if (use_sync_markers && !(evil_scene->toolsettings->lock_markers) && (markers != NULL)) {
+      TimeMarker *marker;
+      /* affect selected markers - it's unlikely that we will want to affect all in this way? */
+      for (marker = markers->first; marker; marker = marker->next) {
+        if (marker->flag & SELECT) {
+          marker->frame += offset;
+        }
+      }
+    }
   }
 
   return offset ? false : true;

source/blender/editors/transform/transform.c

@@ -2561,7 +2561,7 @@ int transformEnd(bContext *C, TransInfo *t)
     /* aftertrans does insert keyframes, and clears base flags; doesn't read transdata */
     special_aftertrans_update(C, t);
 
-    /* free data */
+    /* Free data, also handles overlap [in freeTransCustomData()]. */
     postTrans(C, t);
 
     /* send events out for redraws */

source/blender/editors/transform/transform_convert.c

@@ -1892,8 +1892,8 @@ void special_aftertrans_update(bContext *C, TransInfo *t)
 
     SpaceSeq *sseq = (SpaceSeq *)t->sa->spacedata.first;
 
-    /* marker transform, not especially nice but we may want to move markers
-     * at the same time as keyframes in the dope sheet. */
+    /* Marker transform, not especially nice but we may want to move markers
+     * at the same time as strips in the Video Sequencer. */
     if ((sseq->flag & SEQ_MARKER_TRANS) && (canceled == 0)) {
       /* cant use TFM_TIME_EXTEND
        * for some reason EXTEND is changed into TRANSLATE, so use frame_side instead */

source/blender/editors/transform/transform_convert_sequencer.c

@@ -381,6 +381,10 @@ static void freeSeqData(TransInfo *t, TransDataContainer *tc, TransCustomData *c
         }
 
         if (overlap) {
+          const bool use_sync_markers = (((SpaceSeq *)t->sa->spacedata.first)->flag &
+                                         SEQ_MARKER_TRANS) != 0;
+          ListBase *markers = &t->scene->markers;
+
           bool has_effect_root = false, has_effect_any = false;
           for (seq = seqbasep->first; seq; seq = seq->next) {
             seq->tmp = NULL;
@@ -425,7 +429,7 @@ static void freeSeqData(TransInfo *t, TransDataContainer *tc, TransCustomData *c
               }
             }
 
-            BKE_sequence_base_shuffle_time(seqbasep, t->scene);
+            BKE_sequence_base_shuffle_time(seqbasep, t->scene, markers, use_sync_markers);
 
             for (seq = seqbasep->first; seq; seq = seq->next) {
               if (seq->machine >= MAXSEQ * 2) {
@@ -437,10 +441,10 @@ static void freeSeqData(TransInfo *t, TransDataContainer *tc, TransCustomData *c
               }
             }
 
-            BKE_sequence_base_shuffle_time(seqbasep, t->scene);
+            BKE_sequence_base_shuffle_time(seqbasep, t->scene, markers, use_sync_markers);
           }
           else {
-            BKE_sequence_base_shuffle_time(seqbasep, t->scene);
+            BKE_sequence_base_shuffle_time(seqbasep, t->scene, markers, use_sync_markers);
           }
 
           if (has_effect_any) {