Context: add "active_nla_track" & "active_nla_strip" context members

Selection was already accessible but not active.

Add utility functions:

- ANIM_nla_context_track to access the active track,
  following the convention of ANIM_nla_context_strip.

- ANIM_nla_context_*_ptr versions of these functions,
  needed to for creating context members to access the ID pointer.

Part of fix for T90723.

doc/python_api/sphinx_doc_gen.py

@@ -1047,6 +1047,8 @@ context_type_map = {
     "active_pose_bone": ("PoseBone", False),
     "active_sequence_strip": ("Sequence", False),
     "active_editable_fcurve": ("FCurve", False),
+    "active_nla_strip": ("NlaStrip", False),
+    "active_nla_track": ("NlaTrack", False),
     "annotation_data": ("GreasePencil", False),
     "annotation_data_owner": ("ID", False),
     "armature": ("Armature", False),

source/blender/editors/include/ED_anim_api.h

@@ -678,6 +678,11 @@ void ANIM_draw_framerange(struct Scene *scene, struct View2D *v2d);
 
 /* ------------- UI Panel Drawing -------------- */
 
+
+bool ANIM_nla_context_track_ptr(const struct bContext *C, struct PointerRNA *r_ptr);
+bool ANIM_nla_context_strip_ptr(const struct bContext *C, struct PointerRNA *r_ptr);
+
+struct NlaTrack *ANIM_nla_context_track(const struct bContext *C);
 struct NlaStrip *ANIM_nla_context_strip(const struct bContext *C);
 struct FCurve *ANIM_graph_context_fcurve(const struct bContext *C);
 

source/blender/editors/screen/screen_context.c

@@ -96,7 +96,9 @@ const char *screen_context_dir[] = {
     "sequences",
     "selected_sequences",
     "selected_editable_sequences", /* sequencer */
-    "selected_nla_strips",         /* nla editor */
+    "active_nla_track",
+    "active_nla_strip",
+    "selected_nla_strips", /* nla editor */
     "gpencil_data",
     "gpencil_data_owner", /* grease pencil data */
     "annotation_data",
@@ -664,6 +666,24 @@ static eContextResult screen_ctx_selected_editable_sequences(const bContext *C,
   }
   return CTX_RESULT_NO_DATA;
 }
+static eContextResult screen_ctx_active_nla_track(const bContext *C, bContextDataResult *result)
+{
+  PointerRNA ptr;
+  if (ANIM_nla_context_track_ptr(C, &ptr)) {
+    CTX_data_pointer_set(result, ptr.owner_id, ptr.type, ptr.data);
+    return CTX_RESULT_OK;
+  }
+  return CTX_RESULT_NO_DATA;
+}
+static eContextResult screen_ctx_active_nla_strip(const bContext *C, bContextDataResult *result)
+{
+  PointerRNA ptr;
+  if (ANIM_nla_context_strip_ptr(C, &ptr)) {
+    CTX_data_pointer_set(result, ptr.owner_id, ptr.type, ptr.data);
+    return CTX_RESULT_OK;
+  }
+  return CTX_RESULT_NO_DATA;
+}
 static eContextResult screen_ctx_selected_nla_strips(const bContext *C, bContextDataResult *result)
 {
   bAnimContext ac;
@@ -1115,6 +1135,8 @@ static void ensure_ed_screen_context_functions(void)
   register_context_function("sequences", screen_ctx_sequences);
   register_context_function("selected_sequences", screen_ctx_selected_sequences);
   register_context_function("selected_editable_sequences", screen_ctx_selected_editable_sequences);
+  register_context_function("active_nla_track", screen_ctx_active_nla_track);
+  register_context_function("active_nla_strip", screen_ctx_active_nla_strip);
   register_context_function("selected_nla_strips", screen_ctx_selected_nla_strips);
   register_context_function("gpencil_data", screen_ctx_gpencil_data);
   register_context_function("gpencil_data_owner", screen_ctx_gpencil_data_owner);

source/blender/editors/space_nla/nla_buttons.c

@@ -185,10 +185,31 @@ bool nla_panel_context(const bContext *C,
   return (found != 0);
 }
 
+bool ANIM_nla_context_track_ptr(const bContext *C, PointerRNA *r_ptr)
+{
+  return nla_panel_context(C, NULL, r_ptr, NULL);
+}
+
+bool ANIM_nla_context_strip_ptr(const bContext *C, PointerRNA *r_ptr)
+{
+  return nla_panel_context(C, NULL, NULL, r_ptr);
+}
+
+NlaTrack *ANIM_nla_context_track(const bContext *C)
+{
+  PointerRNA track_ptr;
+  if (!ANIM_nla_context_track_ptr(C, &track_ptr)) {
+    return NULL;
+  }
+  NlaTrack *track = track_ptr.data;
+
+  return track;
+}
+
 NlaStrip *ANIM_nla_context_strip(const bContext *C)
 {
   PointerRNA strip_ptr;
-  if (!nla_panel_context(C, NULL, NULL, &strip_ptr)) {
+  if (!ANIM_nla_context_strip_ptr(C, &strip_ptr)) {
     return NULL;
   }
   NlaStrip *strip = strip_ptr.data;