VSE: Improved Snapping

Change snapping behavior to snap strip edges when they are close to snap point.
Default behavior is, that each transformed strip is snapped to any other strip.

Implement snapping controls in sequencer tool settings. These controls include:

 - Snapping on/off
 - Ability to snap to playhead and strip hold offset points
 - Filter snap points by excluding sound or muted strips
 - Control snapping distance

Snapping controls are placed in timeline header similar to 3D viewport

Reviewed By: mano-wii

Differential Revision: https://developer.blender.org/D11646

4 files changed, 32 insertions, 0 deletions

diff --git a/source/blender/sequencer/SEQ_iterator.h b/source/blender/sequencer/SEQ_iterator.h
index c7c2dc275ee..39d8a7241fb 100644
--- a/source/blender/sequencer/SEQ_iterator.h
+++ b/source/blender/sequencer/SEQ_iterator.h
@@ -71,6 +71,7 @@ bool SEQ_iterator_ensure(SeqCollection *collection,
 struct Sequence *SEQ_iterator_yield(SeqIterator *iterator);
 
 SeqCollection *SEQ_collection_create(void);
+uint SEQ_collection_count(SeqCollection *collection);
 bool SEQ_collection_append_strip(struct Sequence *seq, SeqCollection *data);
 bool SEQ_collection_remove_strip(struct Sequence *seq, SeqCollection *data);
 void SEQ_collection_free(SeqCollection *collection);
diff --git a/source/blender/sequencer/SEQ_sequencer.h b/source/blender/sequencer/SEQ_sequencer.h
index fd4181a5a54..706f4064bf3 100644
--- a/source/blender/sequencer/SEQ_sequencer.h
+++ b/source/blender/sequencer/SEQ_sequencer.h
@@ -55,6 +55,9 @@ struct SequencerToolSettings *SEQ_tool_settings_ensure(struct Scene *scene);
 void SEQ_tool_settings_free(struct SequencerToolSettings *tool_settings);
 eSeqImageFitMethod SEQ_tool_settings_fit_method_get(struct Scene *scene);
 void SEQ_tool_settings_fit_method_set(struct Scene *scene, eSeqImageFitMethod fit_method);
+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);
 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/intern/iterator.c b/source/blender/sequencer/intern/iterator.c
index 9bbc5362f18..4df92ce7df4 100644
--- a/source/blender/sequencer/intern/iterator.c
+++ b/source/blender/sequencer/intern/iterator.c
@@ -115,6 +115,14 @@ SeqCollection *SEQ_collection_create(void)
 }
 
 /**
+ * Return number of items in collection.
+ */
+uint SEQ_collection_count(SeqCollection *collection)
+{
+  return BLI_gset_len(collection->set);
+}
+
+/**
  * Query strips from seqbase. seq_reference is used by query function as filter condition.
  *
  * \param seq_reference: reference strip for query function
diff --git a/source/blender/sequencer/intern/sequencer.c b/source/blender/sequencer/intern/sequencer.c
index 8cd67195c30..f6b37bdb3ab 100644
--- a/source/blender/sequencer/intern/sequencer.c
+++ b/source/blender/sequencer/intern/sequencer.c
@@ -311,6 +311,8 @@ SequencerToolSettings *SEQ_tool_settings_init(void)
   SequencerToolSettings *tool_settings = MEM_callocN(sizeof(SequencerToolSettings),
                                                      "Sequencer tool settings");
   tool_settings->fit_method = SEQ_SCALE_TO_FIT;
+  tool_settings->snap_mode = SEQ_SNAP_TO_STRIPS | SEQ_SNAP_TO_PLAYHEAD | SEQ_SNAP_TO_STRIP_HOLD;
+  tool_settings->snap_distance = 15;
   return tool_settings;
 }
 
@@ -336,6 +338,24 @@ eSeqImageFitMethod SEQ_tool_settings_fit_method_get(Scene *scene)
   return tool_settings->fit_method;
 }
 
+short SEQ_tool_settings_snap_mode_get(Scene *scene)
+{
+  const SequencerToolSettings *tool_settings = SEQ_tool_settings_ensure(scene);
+  return tool_settings->snap_mode;
+}
+
+short SEQ_tool_settings_snap_flag_get(Scene *scene)
+{
+  const SequencerToolSettings *tool_settings = SEQ_tool_settings_ensure(scene);
+  return tool_settings->snap_flag;
+}
+
+int SEQ_tool_settings_snap_distance_get(Scene *scene)
+{
+  const SequencerToolSettings *tool_settings = SEQ_tool_settings_ensure(scene);
+  return tool_settings->snap_distance;
+}
+
 void SEQ_tool_settings_fit_method_set(Scene *scene, eSeqImageFitMethod fit_method)
 {
   SequencerToolSettings *tool_settings = SEQ_tool_settings_ensure(scene);