VSE: Transform overwrite mode

Add mode to overwrite strips on overlap instead of resolving overlap.

When overlap is created, 3 things can happen:
 - On partial overlap, handles of overlapped strip are moved
 - On complete overlap with smaller strip, overlapped strip is split
 - On complete overlap with larger strip, overlapped strip is removed

This mode can be enabled in header.

Reviewed By: fsiddi, mano-wii

Differential Revision: https://developer.blender.org/D11805

14 files changed, 286 insertions, 78 deletions

diff --git a/release/scripts/startup/bl_ui/space_sequencer.py b/release/scripts/startup/bl_ui/space_sequencer.py
index 20fb39e8c1f..79c1cb973ca 100644
--- a/release/scripts/startup/bl_ui/space_sequencer.py
+++ b/release/scripts/startup/bl_ui/space_sequencer.py
@@ -150,6 +150,9 @@ class SEQUENCER_HT_header(Header):
 
         if st.view_type in {'SEQUENCER', 'SEQUENCER_PREVIEW'}:
             tool_settings = context.tool_settings
+            sequencer_tool_settings = tool_settings.sequencer_tool_settings
+            row = layout.row(align=True)
+            row.prop(sequencer_tool_settings, "overlap_mode", text="")
             row = layout.row(align=True)
             row.prop(tool_settings, "use_snap_sequencer", text="")
             sub = row.row(align=True)
diff --git a/source/blender/blenkernel/BKE_blender_version.h b/source/blender/blenkernel/BKE_blender_version.h
index 4ed4225c836..315a77499e5 100644
--- a/source/blender/blenkernel/BKE_blender_version.h
+++ b/source/blender/blenkernel/BKE_blender_version.h
@@ -39,7 +39,7 @@ extern "C" {
 
 /* Blender file format version. */
 #define BLENDER_FILE_VERSION BLENDER_VERSION
-#define BLENDER_FILE_SUBVERSION 18
+#define BLENDER_FILE_SUBVERSION 19
 
 /* Minimum Blender version that supports reading file written with the current
  * version. Older Blender versions will test this and show a warning if the file
diff --git a/source/blender/blenloader/intern/versioning_300.c b/source/blender/blenloader/intern/versioning_300.c
index 72572b05ef6..aee6d798799 100644
--- a/source/blender/blenloader/intern/versioning_300.c
+++ b/source/blender/blenloader/intern/versioning_300.c
@@ -776,18 +776,7 @@ void blo_do_versions_300(FileData *fd, Library *UNUSED(lib), Main *bmain)
     }
   }
 
-  /**
-   * Versioning code until next subversion bump goes here.
-   *
-   * \note Be sure to check when bumping the version:
-   * - "versioning_userdef.c", #blo_do_versions_userdef
-   * - "versioning_userdef.c", #do_versions_theme
-   *
-   * \note Keep this message at the bottom of the function.
-   */
-  {
-    /* Keep this block, even when empty. */
-
+  if (!MAIN_VERSION_ATLEAST(bmain, 300, 19)) {
     /* Add node storage for subdivision surface node. */
     FOREACH_NODETREE_BEGIN (bmain, ntree, id) {
       if (ntree->type == NTREE_GEOMETRY) {
@@ -818,5 +807,23 @@ void blo_do_versions_300(FileData *fd, Library *UNUSED(lib), Main *bmain)
         }
       }
     }
+
+    LISTBASE_FOREACH (Scene *, scene, &bmain->scenes) {
+      SequencerToolSettings *sequencer_tool_settings = SEQ_tool_settings_ensure(scene);
+      sequencer_tool_settings->overlap_mode = SEQ_OVERLAP_SHUFFLE;
+    }
+  }
+
+  /**
+   * Versioning code until next subversion bump goes here.
+   *
+   * \note Be sure to check when bumping the version:
+   * - "versioning_userdef.c", #blo_do_versions_userdef
+   * - "versioning_userdef.c", #do_versions_theme
+   *
+   * \note Keep this message at the bottom of the function.
+   */
+  {
+    /* Keep this block, even when empty. */
   }
 }
diff --git a/source/blender/editors/space_sequencer/sequencer_draw.c b/source/blender/editors/space_sequencer/sequencer_draw.c
index b3c39e2fa6f..fe3ff469e50 100644
--- a/source/blender/editors/space_sequencer/sequencer_draw.c
+++ b/source/blender/editors/space_sequencer/sequencer_draw.c
@@ -737,7 +737,8 @@ static void draw_seq_handle(View2D *v2d,
   }
 }
 
-static void draw_seq_outline(Sequence *seq,
+static void draw_seq_outline(Scene *scene,
+                             Sequence *seq,
                              uint pos,
                              float x1,
                              float x2,
@@ -765,7 +766,9 @@ static void draw_seq_outline(Sequence *seq,
    *  - Slightly lighter.
    *  - Red when overlapping with other strips.
    */
-  if ((G.moving & G_TRANSFORM_SEQ) && (seq->flag & SELECT)) {
+  const eSeqOverlapMode overlap_mode = SEQ_tool_settings_overlap_mode_get(scene);
+  if ((G.moving & G_TRANSFORM_SEQ) && (seq->flag & SELECT) &&
+      overlap_mode != SEQ_OVERLAP_OVERWRITE) {
     if (seq->flag & SEQ_OVERLAP) {
       col[0] = 255;
       col[1] = col[2] = 33;
@@ -1383,7 +1386,7 @@ static void draw_seq_strip(const bContext *C,
         v2d, seq, handsize_clamped, SEQ_RIGHTHANDLE, pos, seq_active, pixelx, y_threshold);
   }
 
-  draw_seq_outline(seq, pos, x1, x2, y1, y2, pixelx, pixely, seq_active);
+  draw_seq_outline(scene, seq, pos, x1, x2, y1, y2, pixelx, pixely, seq_active);
 
   immUnbindProgram();
 
diff --git a/source/blender/editors/transform/transform_convert_sequencer.c b/source/blender/editors/transform/transform_convert_sequencer.c
index 45ed0f3b664..9548498f0b8 100644
--- a/source/blender/editors/transform/transform_convert_sequencer.c
+++ b/source/blender/editors/transform/transform_convert_sequencer.c
@@ -29,10 +29,13 @@
 #include "BLI_math.h"
 
 #include "BKE_context.h"
+#include "BKE_main.h"
 #include "BKE_report.h"
 
 #include "ED_markers.h"
 
+#include "SEQ_edit.h"
+#include "SEQ_effects.h"
 #include "SEQ_iterator.h"
 #include "SEQ_relations.h"
 #include "SEQ_sequencer.h"
@@ -341,12 +344,17 @@ static bool seq_transform_check_strip_effects(SeqCollection *transformed_strips)
   return false;
 }
 
+static ListBase *seqbase_active_get(const TransInfo *t)
+{
+  Editing *ed = SEQ_editing_get(t->scene, false);
+  return SEQ_active_seqbase_get(ed);
+}
+
 /* Offset all strips positioned after left edge of transformed strips boundbox by amount equal
  * to overlap of transformed strips. */
 static void seq_transform_handle_expand_to_fit(TransInfo *t, SeqCollection *transformed_strips)
 {
-  Editing *ed = SEQ_editing_get(t->scene, false);
-  ListBase *seqbasep = SEQ_active_seqbase_get(ed);
+  ListBase *seqbasep = seqbase_active_get(t);
   ListBase *markers = &t->scene->markers;
   const bool use_sync_markers = (((SpaceSeq *)t->area->spacedata.first)->flag &
                                  SEQ_MARKER_TRANS) != 0;
@@ -378,23 +386,178 @@ static void seq_transform_handle_expand_to_fit(TransInfo *t, SeqCollection *tran
   SEQ_collection_free(right_side_strips);
 }
 
-static void seq_transform_handle_overlap(TransInfo *t, SeqCollection *transformed_strips)
+static SeqCollection *query_overwrite_targets(const TransInfo *t,
+                                              SeqCollection *transformed_strips)
 {
-  Editing *ed = SEQ_editing_get(t->scene, false);
-  ListBase *seqbasep = SEQ_active_seqbase_get(ed);
+  SeqCollection *collection = SEQ_query_unselected_strips(seqbase_active_get(t));
+
+  Sequence *seq, *seq_transformed;
+  SEQ_ITERATOR_FOREACH (seq, collection) {
+    bool does_overlap = false;
 
-  if (t->flag & T_ALT_TRANSFORM) {
-    seq_transform_handle_expand_to_fit(t, transformed_strips);
+    SEQ_ITERATOR_FOREACH (seq_transformed, transformed_strips) {
+      /* Effects of transformed strips can be unselected. These must not be included. */
+      if (seq == seq_transformed) {
+        SEQ_collection_remove_strip(seq, collection);
+      }
+      if (SEQ_transform_test_overlap_seq_seq(seq, seq_transformed)) {
+        does_overlap = true;
+      }
+    }
+
+    if (!does_overlap) {
+      SEQ_collection_remove_strip(seq, collection);
+    }
   }
-  else {
-    ListBase *markers = &t->scene->markers;
-    const bool use_sync_markers = (((SpaceSeq *)t->area->spacedata.first)->flag &
-                                   SEQ_MARKER_TRANS) != 0;
-    /* Shuffle non strips with no effects attached. */
-    SeqCollection *standalone_strips = extract_standalone_strips(transformed_strips);
-    SEQ_transform_seqbase_shuffle_time(
-        standalone_strips, seqbasep, t->scene, markers, use_sync_markers);
-    SEQ_collection_free(standalone_strips);
+
+  return collection;
+}
+
+typedef enum eOvelapDescrition {
+  /* No overlap. */
+  STRIP_OVERLAP_NONE,
+  /* Overlapping strip covers overlapped completely. */
+  STRIP_OVERLAP_IS_FULL,
+  /* Overlapping strip is inside overlapped. */
+  STRIP_OVERLAP_IS_INSIDE,
+  /* Partial overlap between 2 strips. */
+  STRIP_OVERLAP_LEFT_SIDE,
+  STRIP_OVERLAP_RIGHT_SIDE,
+} eOvelapDescrition;
+
+static eOvelapDescrition overlap_description_get(const Sequence *transformed,
+                                                 const Sequence *target)
+{
+  if (transformed->startdisp <= target->startdisp && transformed->enddisp >= target->enddisp) {
+    return STRIP_OVERLAP_IS_FULL;
+  }
+  if (transformed->startdisp > target->startdisp && transformed->enddisp < target->enddisp) {
+    return STRIP_OVERLAP_IS_INSIDE;
+  }
+  if (transformed->startdisp <= target->startdisp && target->startdisp <= transformed->enddisp) {
+    return STRIP_OVERLAP_LEFT_SIDE;
+  }
+  if (transformed->startdisp <= target->enddisp && target->enddisp <= transformed->enddisp) {
+    return STRIP_OVERLAP_RIGHT_SIDE;
+  }
+  return STRIP_OVERLAP_NONE;
+}
+
+/* Split strip in 3 parts, remove middle part and fit transformed inside. */
+static void seq_transform_handle_overwrite_split(const TransInfo *t,
+                                                 const Sequence *transformed,
+                                                 Sequence *target)
+{
+  Main *bmain = CTX_data_main(t->context);
+  Scene *scene = t->scene;
+  ListBase *seqbase = seqbase_active_get(t);
+
+  Sequence *split_strip = SEQ_edit_strip_split(
+      bmain, scene, seqbase, target, transformed->startdisp, SEQ_SPLIT_SOFT, NULL);
+  SEQ_edit_strip_split(
+      bmain, scene, seqbase, split_strip, transformed->enddisp, SEQ_SPLIT_SOFT, NULL);
+  SEQ_edit_flag_for_removal(scene, seqbase_active_get(t), split_strip);
+}
+
+/* Trim strips by adjusting handle position.
+ * This is bit more complicated in case overlap happens on effect. */
+static void seq_transform_handle_overwrite_trim(const TransInfo *t,
+                                                const Sequence *transformed,
+                                                Sequence *target,
+                                                const eOvelapDescrition overlap)
+{
+  SeqCollection *targets = SEQ_query_by_reference(
+      target, seqbase_active_get(t), SEQ_query_strip_effect_chain);
+
+  /* Expand collection by adding all target's children, effects and their children. */
+  if ((target->type & SEQ_TYPE_EFFECT) != 0) {
+    SEQ_collection_expand(seqbase_active_get(t), targets, SEQ_query_strip_effect_chain);
+  }
+
+  /* Trim all non effects, that have influence on effect length which is overlapping. */
+  Sequence *seq;
+  SEQ_ITERATOR_FOREACH (seq, targets) {
+    if ((seq->type & SEQ_TYPE_EFFECT) != 0 && SEQ_effect_get_num_inputs(seq->type) > 0) {
+      continue;
+    }
+    if (overlap == STRIP_OVERLAP_LEFT_SIDE) {
+      SEQ_transform_set_left_handle_frame(seq, transformed->enddisp);
+    }
+    else {
+      BLI_assert(overlap == STRIP_OVERLAP_RIGHT_SIDE);
+      SEQ_transform_set_right_handle_frame(seq, transformed->startdisp);
+    }
+    SEQ_time_update_sequence(t->scene, seq);
+  }
+  SEQ_collection_free(targets);
+}
+
+static void seq_transform_handle_overwrite(const TransInfo *t, SeqCollection *transformed_strips)
+{
+  SeqCollection *targets = query_overwrite_targets(t, transformed_strips);
+
+  bool strips_delete = false;
+  Sequence *target;
+  Sequence *transformed;
+  SEQ_ITERATOR_FOREACH (target, targets) {
+    SEQ_ITERATOR_FOREACH (transformed, transformed_strips) {
+      if (transformed->machine != target->machine) {
+        continue;
+      }
+
+      const eOvelapDescrition overlap = overlap_description_get(transformed, target);
+
+      if (overlap == STRIP_OVERLAP_IS_FULL) {
+        /* Remove covered strip. */
+        SEQ_edit_flag_for_removal(t->scene, seqbase_active_get(t), target);
+        strips_delete = true;
+      }
+      else if (overlap == STRIP_OVERLAP_IS_INSIDE) {
+        seq_transform_handle_overwrite_split(t, transformed, target);
+        strips_delete = true;
+      }
+      else if (ELEM(overlap, STRIP_OVERLAP_LEFT_SIDE, STRIP_OVERLAP_RIGHT_SIDE)) {
+        seq_transform_handle_overwrite_trim(t, transformed, target, overlap);
+      }
+    }
+  }
+
+  SEQ_collection_free(targets);
+
+  if (strips_delete) {
+    SEQ_edit_remove_flagged_sequences(t->scene, seqbase_active_get(t));
+  }
+}
+
+static void seq_transform_handle_overlap_shuffle(const TransInfo *t,
+                                                 SeqCollection *transformed_strips)
+{
+  ListBase *seqbase = seqbase_active_get(t);
+  ListBase *markers = &t->scene->markers;
+  const bool use_sync_markers = (((SpaceSeq *)t->area->spacedata.first)->flag &
+                                 SEQ_MARKER_TRANS) != 0;
+  /* Shuffle non strips with no effects attached. */
+  SeqCollection *standalone_strips = extract_standalone_strips(transformed_strips);
+  SEQ_transform_seqbase_shuffle_time(
+      standalone_strips, seqbase, t->scene, markers, use_sync_markers);
+  SEQ_collection_free(standalone_strips);
+}
+
+static void seq_transform_handle_overlap(TransInfo *t, SeqCollection *transformed_strips)
+{
+  ListBase *seqbasep = seqbase_active_get(t);
+  const eSeqOverlapMode overlap_mode = SEQ_tool_settings_overlap_mode_get(t->scene);
+
+  switch (overlap_mode) {
+    case SEQ_OVERLAP_EXPAND:
+      seq_transform_handle_expand_to_fit(t, transformed_strips);
+      break;
+    case SEQ_OVERLAP_OVERWRITE:
+      seq_transform_handle_overwrite(t, transformed_strips);
+      break;
+    case SEQ_OVERLAP_SHUFFLE:
+      seq_transform_handle_overlap_shuffle(t, transformed_strips);
+      break;
   }
 
   if (seq_transform_check_strip_effects(transformed_strips)) {
@@ -409,6 +572,7 @@ static void seq_transform_handle_overlap(TransInfo *t, SeqCollection *transforme
     if (SEQ_transform_test_overlap(seqbasep, seq)) {
       SEQ_transform_seqbase_shuffle(seqbasep, seq, t->scene);
     }
+    seq->flag &= ~SEQ_OVERLAP;
   }
 }
 
@@ -432,6 +596,7 @@ static void freeSeqData(TransInfo *t, TransDataContainer *tc, TransCustomData *c
   }
 
   SeqCollection *transformed_strips = seq_transform_collection_from_transdata(tc);
+  SEQ_collection_expand(seqbase_active_get(t), transformed_strips, SEQ_query_strip_effect_chain);
 
   if (t->state == TRANS_CANCEL) {
     seq_transform_cancel(t, transformed_strips);
@@ -549,7 +714,7 @@ BLI_INLINE void trans_update_seq(Scene *sce, Sequence *seq, int old_start, int s
 static void flushTransSeq(TransInfo *t)
 {
   /* Editing null check already done */
-  ListBase *seqbasep = SEQ_editing_get(t->scene, false)->seqbasep;
+  ListBase *seqbasep = seqbase_active_get(t);
 
   int a, new_frame;
   TransData *td = NULL;
@@ -601,22 +766,17 @@ static void flushTransSeq(TransInfo *t)
 
   /* need to do the overlap check in a new loop otherwise adjacent strips
    * will not be updated and we'll get false positives */
-  Sequence *seq_prev = NULL;
-  seq_prev = NULL;
-  for (a = 0, td = tc->data, td2d = tc->data_2d; a < tc->data_len; a++, td++, td2d++) {
-
-    tdsq = (TransDataSeq *)td->extra;
-    seq = tdsq->seq;
+  SeqCollection *transformed_strips = seq_transform_collection_from_transdata(tc);
+  SEQ_collection_expand(seqbase_active_get(t), transformed_strips, SEQ_query_strip_effect_chain);
 
-    if (seq != seq_prev) {
-      /* test overlap, displays red outline */
-      seq->flag &= ~SEQ_OVERLAP;
-      if (SEQ_transform_test_overlap(seqbasep, seq)) {
-        seq->flag |= SEQ_OVERLAP;
-      }
+  SEQ_ITERATOR_FOREACH (seq, transformed_strips) {
+    /* test overlap, displays red outline */
+    seq->flag &= ~SEQ_OVERLAP;
+    if (SEQ_transform_test_overlap(seqbasep, seq)) {
+      seq->flag |= SEQ_OVERLAP;
     }
-    seq_prev = seq;
   }
+  SEQ_collection_free(transformed_strips);
 }
 
 /* helper for recalcData() - for sequencer transforms */
diff --git a/source/blender/editors/transform/transform_mode_edge_seq_slide.c b/source/blender/editors/transform/transform_mode_edge_seq_slide.c
index a8f7fc43b5e..fb70d04a530 100644
--- a/source/blender/editors/transform/transform_mode_edge_seq_slide.c
+++ b/source/blender/editors/transform/transform_mode_edge_seq_slide.c
@@ -54,18 +54,6 @@
 /** \name Transform (Sequencer Slide)
  * \{ */
 
-static eRedrawFlag seq_slide_handleEvent(struct TransInfo *t, const wmEvent *event)
-{
-  BLI_assert(t->mode == TFM_SEQ_SLIDE);
-  const wmKeyMapItem *kmi = t->custom.mode.data;
-  if (kmi && event->type == kmi->type && event->val == kmi->val) {
-    /* Allows the "Expand to Fit" effect to be enabled as a toggle. */
-    t->flag ^= T_ALT_TRANSFORM;
-    return TREDRAW_HARD;
-  }
-  return TREDRAW_NOTHING;
-}
-
 static void headerSeqSlide(TransInfo *t, const float val[2], char str[UI_MAX_DRAW_STR])
 {
   char tvec[NUM_STR_REP_LEN * 3];
@@ -79,17 +67,7 @@ static void headerSeqSlide(TransInfo *t, const float val[2], char str[UI_MAX_DRA
   }
 
   ofs += BLI_snprintf_rlen(
-      str + ofs, UI_MAX_DRAW_STR - ofs, TIP_("Sequence Slide: %s%s, ("), &tvec[0], t->con.text);
-
-  const wmKeyMapItem *kmi = t->custom.mode.data;
-  if (kmi) {
-    ofs += WM_keymap_item_to_string(kmi, false, str + ofs, UI_MAX_DRAW_STR - ofs);
-  }
-
-  ofs += BLI_snprintf_rlen(str + ofs,
-                           UI_MAX_DRAW_STR - ofs,
-                           TIP_(" or Alt) Expand to fit %s"),
-                           WM_bool_as_string((t->flag & T_ALT_TRANSFORM) != 0));
+      str + ofs, UI_MAX_DRAW_STR - ofs, TIP_("Sequence Slide: %s%s"), &tvec[0], t->con.text);
 }
 
 static void applySeqSlideValue(TransInfo *t, const float val[2])
@@ -148,7 +126,6 @@ static void applySeqSlide(TransInfo *t, const int UNUSED(mval[2]))
 void initSeqSlide(TransInfo *t)
 {
   t->transform = applySeqSlide;
-  t->handleEvent = seq_slide_handleEvent;
   t->tsnap.applySnap = transform_snap_sequencer_apply_translate;
 
   initMouseInputMode(t, &t->mouse, INPUT_VECTOR);
diff --git a/source/blender/makesdna/DNA_scene_types.h b/source/blender/makesdna/DNA_scene_types.h
index 3cd5a068e86..7800e7f9efe 100644
--- a/source/blender/makesdna/DNA_scene_types.h
+++ b/source/blender/makesdna/DNA_scene_types.h
@@ -1339,12 +1339,19 @@ typedef struct SequencerToolSettings {
   int fit_method;
   short snap_mode;
   short snap_flag;
-  int _pad0;
+  /* eSeqOverlapMode */
+  int overlap_mode;
   /** When there are many snap points, 0-1 range corresponds to resolution from boundbox to all
    * possible snap points. */
   int snap_distance;
 } SequencerToolSettings;
 
+typedef enum eSeqOverlapMode {
+  SEQ_OVERLAP_EXPAND,
+  SEQ_OVERLAP_OVERWRITE,
+  SEQ_OVERLAP_SHUFFLE,
+} eSeqOverlapMode;
+
 typedef enum eSeqImageFitMethod {
   SEQ_SCALE_TO_FIT,
   SEQ_SCALE_TO_FILL,
diff --git a/source/blender/makesrna/intern/rna_scene.c b/source/blender/makesrna/intern/rna_scene.c
index 9d158761a21..0583cdeb1bb 100644
--- a/source/blender/makesrna/intern/rna_scene.c
+++ b/source/blender/makesrna/intern/rna_scene.c
@@ -3510,6 +3510,21 @@ static void rna_def_sequencer_tool_settings(BlenderRNA *brna)
       {0, NULL, 0, NULL, NULL},
   };
 
+  static const EnumPropertyItem scale_overlap_modes[] = {
+      {SEQ_OVERLAP_EXPAND, "EXPAND", 0, "Expand", "Move strips so transformed strips fits"},
+      {SEQ_OVERLAP_OVERWRITE,
+       "OVERWRITE",
+       0,
+       "Overwrite",
+       "Trim or split strips to resolve overlap"},
+      {SEQ_OVERLAP_SHUFFLE,
+       "SHUFFLE",
+       0,
+       "Shuffle",
+       "Move transformed strips to nearest free space to resolve overlap"},
+      {0, NULL, 0, NULL, NULL},
+  };
+
   srna = RNA_def_struct(brna, "SequencerToolSettings", NULL);
   RNA_def_struct_path_func(srna, "rna_SequencerToolSettings_path");
   RNA_def_struct_ui_text(srna, "Sequencer Tool Settings", "");
@@ -3548,6 +3563,11 @@ static void rna_def_sequencer_tool_settings(BlenderRNA *brna)
   RNA_def_property_int_default(prop, 15);
   RNA_def_property_ui_range(prop, 0, 50, 1, 1);
   RNA_def_property_ui_text(prop, "Snapping Distance", "Maximum distance for snapping in pixels");
+
+  /* Transform overlap handling. */
+  prop = RNA_def_property(srna, "overlap_mode", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, scale_overlap_modes);
+  RNA_def_property_ui_text(prop, "Overlap Mode", "How to resolve overlap after transformation");
 }
 
 static void rna_def_unified_paint_settings(BlenderRNA *brna)
diff --git a/source/blender/sequencer/SEQ_iterator.h b/source/blender/sequencer/SEQ_iterator.h
index 055db07f646..9fca25653e1 100644
--- a/source/blender/sequencer/SEQ_iterator.h
+++ b/source/blender/sequencer/SEQ_iterator.h
@@ -34,10 +34,12 @@ struct GSet;
 struct GSetIterator;
 struct Sequence;
 
-#define SEQ_ITERATOR_FOREACH(var, collection) \
-  for (SeqIterator iter = {{{NULL}}}; \
-       SEQ_iterator_ensure(collection, &iter, &var) && var != NULL; \
-       var = SEQ_iterator_yield(&iter))
+#define SEQ_ITERATOR_FOREACH_IMPL(var, collection, suffix) \
+  for (SeqIterator iter##suffix = {{{NULL}}}; \
+       SEQ_iterator_ensure(collection, &iter##suffix, &var) && var != NULL; \
+       var = SEQ_iterator_yield(&iter##suffix))
+
+#define SEQ_ITERATOR_FOREACH(var, collection) SEQ_ITERATOR_FOREACH_IMPL(var, collection, __LINE__)
 
 typedef struct SeqCollection {
   struct GSet *set;
@@ -79,6 +81,7 @@ SeqCollection *SEQ_query_by_reference(struct Sequence *seq_reference,
                                                           struct ListBase *seqbase,
                                                           SeqCollection *collection));
 SeqCollection *SEQ_query_selected_strips(struct ListBase *seqbase);
+SeqCollection *SEQ_query_unselected_strips(struct ListBase *seqbase);
 SeqCollection *SEQ_query_all_strips(struct ListBase *seqbase);
 SeqCollection *SEQ_query_all_strips_recursive(struct ListBase *seqbase);
 void SEQ_query_strip_effect_chain(struct Sequence *seq_reference,
diff --git a/source/blender/sequencer/SEQ_sequencer.h b/source/blender/sequencer/SEQ_sequencer.h
index 54ef37b9049..15fe0be3571 100644
--- a/source/blender/sequencer/SEQ_sequencer.h
+++ b/source/blender/sequencer/SEQ_sequencer.h
@@ -63,6 +63,7 @@ void SEQ_tool_settings_fit_method_set(struct Scene *scene, eSeqImageFitMethod fi
 short SEQ_tool_settings_snap_flag_get(struct Scene *scene);
 short SEQ_tool_settings_snap_mode_get(struct Scene *scene);
 int SEQ_tool_settings_snap_distance_get(struct Scene *scene);
+eSeqOverlapMode SEQ_tool_settings_overlap_mode_get(struct Scene *scene);
 struct SequencerToolSettings *SEQ_tool_settings_copy(struct SequencerToolSettings *tool_settings);
 struct Editing *SEQ_editing_get(struct Scene *scene, bool alloc);
 struct Editing *SEQ_editing_ensure(struct Scene *scene);
diff --git a/source/blender/sequencer/SEQ_transform.h b/source/blender/sequencer/SEQ_transform.h
index 9ff827333be..1977835f627 100644
--- a/source/blender/sequencer/SEQ_transform.h
+++ b/source/blender/sequencer/SEQ_transform.h
@@ -41,6 +41,7 @@ bool SEQ_transform_sequence_can_be_translated(struct Sequence *seq);
 bool SEQ_transform_single_image_check(struct Sequence *seq);
 void SEQ_transform_fix_single_image_seq_offsets(struct Sequence *seq);
 bool SEQ_transform_test_overlap(struct ListBase *seqbasep, struct Sequence *test);
+bool SEQ_transform_test_overlap_seq_seq(struct Sequence *seq1, struct Sequence *seq2);
 void SEQ_transform_translate_sequence(struct Scene *scene, struct Sequence *seq, int delta);
 bool SEQ_transform_seqbase_shuffle_ex(struct ListBase *seqbasep,
                                       struct Sequence *test,
diff --git a/source/blender/sequencer/intern/iterator.c b/source/blender/sequencer/intern/iterator.c
index a9cbf4879f1..58f68205f51 100644
--- a/source/blender/sequencer/intern/iterator.c
+++ b/source/blender/sequencer/intern/iterator.c
@@ -341,6 +341,24 @@ SeqCollection *SEQ_query_selected_strips(ListBase *seqbase)
 }
 
 /**
+ * Query all unselected strips in seqbase.
+ *
+ * \param seqbase: ListBase in which strips are queried
+ * \return strip collection
+ */
+SeqCollection *SEQ_query_unselected_strips(ListBase *seqbase)
+{
+  SeqCollection *collection = SEQ_collection_create(__func__);
+  LISTBASE_FOREACH (Sequence *, seq, seqbase) {
+    if ((seq->flag & SELECT) != 0) {
+      continue;
+    }
+    SEQ_collection_append_strip(seq, collection);
+  }
+  return collection;
+}
+
+/**
  * Query all effect strips that are directly or indirectly connected to seq_reference.
  * This includes all effects of seq_reference, strips used by another inputs and their effects, so
  * that whole chain is fully independent of other strips.
diff --git a/source/blender/sequencer/intern/sequencer.c b/source/blender/sequencer/intern/sequencer.c
index 2863af8fb2e..a62b76cd832 100644
--- a/source/blender/sequencer/intern/sequencer.c
+++ b/source/blender/sequencer/intern/sequencer.c
@@ -323,6 +323,8 @@ SequencerToolSettings *SEQ_tool_settings_init(void)
   tool_settings->snap_mode = SEQ_SNAP_TO_STRIPS | SEQ_SNAP_TO_CURRENT_FRAME |
                              SEQ_SNAP_TO_STRIP_HOLD;
   tool_settings->snap_distance = 15;
+  tool_settings->overlap_mode = SEQ_OVERLAP_SHUFFLE;
+
   return tool_settings;
 }
 
@@ -372,6 +374,12 @@ void SEQ_tool_settings_fit_method_set(Scene *scene, eSeqImageFitMethod fit_metho
   tool_settings->fit_method = fit_method;
 }
 
+eSeqOverlapMode SEQ_tool_settings_overlap_mode_get(Scene *scene)
+{
+  const SequencerToolSettings *tool_settings = SEQ_tool_settings_ensure(scene);
+  return tool_settings->overlap_mode;
+}
+
 /**
  * Get seqbase that is being viewed currently. This can be main seqbase or meta strip seqbase
  *
diff --git a/source/blender/sequencer/intern/strip_transform.c b/source/blender/sequencer/intern/strip_transform.c
index 9f69f434ca0..3a5f93a72b0 100644
--- a/source/blender/sequencer/intern/strip_transform.c
+++ b/source/blender/sequencer/intern/strip_transform.c
@@ -208,7 +208,7 @@ bool SEQ_transform_sequence_can_be_translated(Sequence *seq)
   return !(seq->type & SEQ_TYPE_EFFECT) || (SEQ_effect_get_num_inputs(seq->type) == 0);
 }
 
-static bool seq_overlap(Sequence *seq1, Sequence *seq2)
+bool SEQ_transform_test_overlap_seq_seq(Sequence *seq1, Sequence *seq2)
 {
   return (seq1 != seq2 && seq1->machine == seq2->machine &&
           ((seq1->enddisp <= seq2->startdisp) || (seq1->startdisp >= seq2->enddisp)) == 0);
@@ -220,7 +220,7 @@ bool SEQ_transform_test_overlap(ListBase *seqbasep, Sequence *test)
 
   seq = seqbasep->first;
   while (seq) {
-    if (seq_overlap(test, seq)) {
+    if (SEQ_transform_test_overlap_seq_seq(test, seq)) {
       return true;
     }
 
@@ -316,7 +316,7 @@ static int shuffle_seq_time_offset_test(SeqCollection *strips_to_shuffle,
 
   SEQ_ITERATOR_FOREACH (seq, strips_to_shuffle) {
     LISTBASE_FOREACH (Sequence *, seq_other, seqbasep) {
-      if (!seq_overlap(seq, seq_other)) {
+      if (!SEQ_transform_test_overlap_seq_seq(seq, seq_other)) {
         continue;
       }
       if (UNLIKELY(SEQ_collection_has_strip(seq_other, strips_to_shuffle))) {