From 6b35d9e6fbef49d4ce61604c27393425c16cd7a6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?F=C3=A9lix?= <Miadim>
Date: Mon, 27 Jun 2022 19:29:41 +0200
Subject: VSE: Add API function to select displayed meta strip

Use function `sequence_editor.display_stack(meta_strip)` to set
displayed timeline content.

To view top-level timeline, that does not belong to any meta strip, pass
`None` as argument.

Differential Revision: https://developer.blender.org/D12048
---
 source/blender/sequencer/intern/sequencer.c | 55 +++++++++++++++++++++++------
 1 file changed, 45 insertions(+), 10 deletions(-)

(limited to 'source/blender/sequencer/intern/sequencer.c')

diff --git a/source/blender/sequencer/intern/sequencer.c b/source/blender/sequencer/intern/sequencer.c
index ad57412034a..71f4aef6916 100644
--- a/source/blender/sequencer/intern/sequencer.c
+++ b/source/blender/sequencer/intern/sequencer.c
@@ -397,23 +397,23 @@ void SEQ_seqbase_active_set(Editing *ed, ListBase *seqbase)
   ed->seqbasep = seqbase;
 }
 
-MetaStack *SEQ_meta_stack_alloc(Editing *ed, Sequence *seq_meta)
+static MetaStack *seq_meta_stack_alloc(const Scene *scene, Sequence *seq_meta)
 {
+  Editing *ed = SEQ_editing_get(scene);
+
   MetaStack *ms = MEM_mallocN(sizeof(MetaStack), "metastack");
-  BLI_addtail(&ed->metastack, ms);
+  BLI_addhead(&ed->metastack, ms);
   ms->parseq = seq_meta;
-  ms->oldbasep = ed->seqbasep;
-  ms->old_channels = ed->displayed_channels;
+
+  /* Reference to previously displayed timeline data. */
+  Sequence *higher_level_meta = seq_sequence_lookup_meta_by_seq(scene, seq_meta);
+  ms->oldbasep = higher_level_meta ? &higher_level_meta->seqbase : &ed->seqbase;
+  ms->old_channels = higher_level_meta ? &higher_level_meta->channels : &ed->channels;
+
   copy_v2_v2_int(ms->disp_range, &ms->parseq->startdisp);
   return ms;
 }
 
-void SEQ_meta_stack_free(Editing *ed, MetaStack *ms)
-{
-  BLI_remlink(&ed->metastack, ms);
-  MEM_freeN(ms);
-}
-
 MetaStack *SEQ_meta_stack_active_get(const Editing *ed)
 {
   if (ed == NULL) {
@@ -423,6 +423,41 @@ MetaStack *SEQ_meta_stack_active_get(const Editing *ed)
   return ed->metastack.last;
 }
 
+void SEQ_meta_stack_set(const Scene *scene, Sequence *seqm)
+{
+  Editing *ed = SEQ_editing_get(scene);
+  /* Clear metastack */
+  BLI_freelistN(&ed->metastack);
+
+  if (seqm != NULL) {
+    /* Allocate meta stack in a way, that represents meta hierarchy in timeline. */
+    seq_meta_stack_alloc(scene, seqm);
+    Sequence *meta_parent = seqm;
+    while (meta_parent = seq_sequence_lookup_meta_by_seq(scene, meta_parent)) {
+      seq_meta_stack_alloc(scene, meta_parent);
+    }
+
+    SEQ_seqbase_active_set(ed, &seqm->seqbase);
+    SEQ_channels_displayed_set(ed, &seqm->channels);
+  }
+  else {
+    /* Go to top level, exiting meta strip. */
+    SEQ_seqbase_active_set(ed, &ed->seqbase);
+    SEQ_channels_displayed_set(ed, &ed->channels);
+  }
+}
+
+Sequence *SEQ_meta_stack_pop(Editing *ed)
+{
+  MetaStack *ms = SEQ_meta_stack_active_get(ed);
+  Sequence *meta_parent = ms->parseq;
+  SEQ_seqbase_active_set(ed, ms->oldbasep);
+  SEQ_channels_displayed_set(ed, ms->old_channels);
+  BLI_remlink(&ed->metastack, ms);
+  MEM_freeN(ms);
+  return meta_parent;
+}
+
 /** \} */
 
 /* -------------------------------------------------------------------- */
-- 
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