VSE: Add new_meta RNA API function

This function can be used to create empty meta strip, which is not
straightforward when using operators. Very useful for import/export
scripts.

Reviewed By: ISS

Differential Revision: https://developer.blender.org/D10661

3 files changed, 84 insertions, 1 deletions

diff --git a/source/blender/makesrna/intern/rna_sequencer_api.c b/source/blender/makesrna/intern/rna_sequencer_api.c
index 04ca3cfdb32..a6a0e9d3dcd 100644
--- a/source/blender/makesrna/intern/rna_sequencer_api.c
+++ b/source/blender/makesrna/intern/rna_sequencer_api.c
@@ -382,6 +382,32 @@ static Sequence *rna_Sequences_meta_new_sound(ID *id,
       id, &seq->seqbase, bmain, reports, name, file, channel, frame_start);
 }
 
+/* Meta sequence
+ * Possibility to create an empty meta to avoid plenty of meta toggling
+ * Created meta have a length equal to 1, must be set through the API. */
+static Sequence *rna_Sequences_new_meta(
+    ID *id, ListBase *seqbase, const char *name, int channel, int frame_start)
+{
+  Scene *scene = (Scene *)id;
+  SeqLoadData load_data;
+  SEQ_add_load_data_init(&load_data, name, NULL, frame_start, channel);
+  Sequence *seqm = SEQ_add_meta_strip(scene, seqbase, &load_data);
+
+  return seqm;
+}
+
+static Sequence *rna_Sequences_editing_new_meta(
+    ID *id, Editing *ed, const char *name, int channel, int frame_start)
+{
+  return rna_Sequences_new_meta(id, &ed->seqbase, name, channel, frame_start);
+}
+
+static Sequence *rna_Sequences_meta_new_meta(
+    ID *id, Sequence *seq, const char *name, int channel, int frame_start)
+{
+  return rna_Sequences_new_meta(id, &seq->seqbase, name, channel, frame_start);
+}
+
 static Sequence *rna_Sequences_new_effect(ID *id,
                                           ListBase *seqbase,
                                           ReportList *reports,
@@ -626,7 +652,11 @@ void RNA_api_sequence_strip(StructRNA *srna)
 
   func = RNA_def_function(srna, "move_to_meta", "rna_Sequences_move_strip_to_meta");
   RNA_def_function_flag(func, FUNC_USE_SELF_ID | FUNC_USE_MAIN);
-  parm = RNA_def_pointer(func, "meta_sequence", "Sequence", "Destination Meta Sequence", "Meta to move the strip into");
+  parm = RNA_def_pointer(func,
+                         "meta_sequence",
+                         "Sequence",
+                         "Destination Meta Sequence",
+                         "Meta to move the strip into");
   RNA_def_parameter_flags(parm, PROP_NEVER_NULL, PARM_REQUIRED);
 
   func = RNA_def_function(srna, "invalidate_cache", "rna_Sequence_invalidate_cache_rnafunc");
@@ -699,6 +729,7 @@ void RNA_api_sequences(BlenderRNA *brna, PropertyRNA *cprop, const bool metastri
   const char *new_image_func_name = "rna_Sequences_editing_new_image";
   const char *new_movie_func_name = "rna_Sequences_editing_new_movie";
   const char *new_sound_func_name = "rna_Sequences_editing_new_sound";
+  const char *new_meta_func_name = "rna_Sequences_editing_new_meta";
   const char *new_effect_func_name = "rna_Sequences_editing_new_effect";
   const char *remove_func_name = "rna_Sequences_editing_remove";
 
@@ -713,6 +744,7 @@ void RNA_api_sequences(BlenderRNA *brna, PropertyRNA *cprop, const bool metastri
     new_image_func_name = "rna_Sequences_meta_new_image";
     new_movie_func_name = "rna_Sequences_meta_new_movie";
     new_sound_func_name = "rna_Sequences_meta_new_sound";
+    new_meta_func_name = "rna_Sequences_meta_new_meta";
     new_effect_func_name = "rna_Sequences_meta_new_effect";
     remove_func_name = "rna_Sequences_meta_remove";
   }
@@ -868,6 +900,28 @@ void RNA_api_sequences(BlenderRNA *brna, PropertyRNA *cprop, const bool metastri
   parm = RNA_def_pointer(func, "sequence", "Sequence", "", "New Sequence");
   RNA_def_function_return(func, parm);
 
+  func = RNA_def_function(srna, "new_meta", new_meta_func_name);
+  RNA_def_function_flag(func, FUNC_USE_SELF_ID);
+  RNA_def_function_ui_description(func, "Add a new meta sequence");
+  parm = RNA_def_string(func, "name", "Name", 0, "", "Name for the new sequence");
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  parm = RNA_def_int(
+      func, "channel", 0, 1, MAXSEQ, "Channel", "The channel for the new sequence", 1, MAXSEQ);
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  parm = RNA_def_int(func,
+                     "frame_start",
+                     0,
+                     -MAXFRAME,
+                     MAXFRAME,
+                     "",
+                     "The start frame for the new sequence",
+                     -MAXFRAME,
+                     MAXFRAME);
+  RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
+  /* return type */
+  parm = RNA_def_pointer(func, "sequence", "Sequence", "", "New Sequence");
+  RNA_def_function_return(func, parm);
+
   func = RNA_def_function(srna, "new_effect", new_effect_func_name);
   RNA_def_function_flag(func, FUNC_USE_REPORTS | FUNC_USE_SELF_ID);
   RNA_def_function_ui_description(func, "Add a new effect sequence");
diff --git a/source/blender/sequencer/SEQ_add.h b/source/blender/sequencer/SEQ_add.h
index 7d728b25a30..983f5ab1391 100644
--- a/source/blender/sequencer/SEQ_add.h
+++ b/source/blender/sequencer/SEQ_add.h
@@ -79,6 +79,9 @@ struct Sequence *SEQ_add_sound_strip(struct Main *bmain,
                                      struct Scene *scene,
                                      struct ListBase *seqbase,
                                      struct SeqLoadData *load_data);
+struct Sequence *SEQ_add_meta_strip(struct Scene *scene,
+                                     struct ListBase *seqbase,
+                                     struct SeqLoadData *load_data);
 struct Sequence *SEQ_add_movie_strip(struct Main *bmain,
                                      struct Scene *scene,
                                      struct ListBase *seqbase,
diff --git a/source/blender/sequencer/intern/strip_add.c b/source/blender/sequencer/intern/strip_add.c
index 54e71ff0698..aab522da659 100644
--- a/source/blender/sequencer/intern/strip_add.c
+++ b/source/blender/sequencer/intern/strip_add.c
@@ -413,6 +413,32 @@ Sequence *SEQ_add_sound_strip(Main *UNUSED(bmain),
 #endif  // WITH_AUDASPACE
 
 /**
+ * Add meta strip.
+ *
+ * \param scene: Scene where strips will be added
+ * \param seqbase: ListBase where strips will be added
+ * \param load_data: SeqLoadData with information necessary to create strip
+ * \return created strip
+ */
+
+Sequence *SEQ_add_meta_strip(Scene *scene, ListBase *seqbase, SeqLoadData *load_data)
+{
+  /* Allocate sequence. */
+  Sequence *seqm = SEQ_sequence_alloc(
+      seqbase, load_data->start_frame, load_data->channel, SEQ_TYPE_META);
+
+  /* Set name. */
+  seq_add_set_name(seqm, load_data);
+
+  /* Set frames start and length. */
+  seqm->start = load_data->start_frame;
+  seqm->len = 1;
+  SEQ_time_update_sequence(scene, seqm);
+
+  return seqm;
+}
+
+/**
  * Add movie strip.
  *
  * \param main: Main reference