Animation: enforce that the active keyframe is always selected

Check selection state in `BKE_fcurve_active_keyframe_index()`, and only
return the active keyframe index when that keyframe is actually selected.
This is now also asserted in the `BKE_fcurve_active_keyframe_set()` function,
which is now also used when inserting a keyframe.

1 files changed, 9 insertions, 1 deletions

diff --git a/source/blender/blenkernel/intern/fcurve.c b/source/blender/blenkernel/intern/fcurve.c
index d2a9064a373..d57ef45107c 100644
--- a/source/blender/blenkernel/intern/fcurve.c
+++ b/source/blender/blenkernel/intern/fcurve.c
@@ -839,6 +839,8 @@ bool BKE_fcurve_calc_range(
  */
 void BKE_fcurve_active_keyframe_set(FCurve *fcu, const BezTriple *active_bezt)
 {
+  /* The active keyframe should always be selected. */
+  BLI_assert(active_bezt->f2 & SELECT);
   fcu->active_keyframe_index = (active_bezt == NULL) ? FCURVE_ACTIVE_KEYFRAME_NONE :
                                                        active_bezt - fcu->bezt;
 }
@@ -850,12 +852,18 @@ int BKE_fcurve_active_keyframe_index(const FCurve *fcu)
 {
   const int active_keyframe_index = fcu->active_keyframe_index;
 
-  /* Sanity checks. */
+  /* Array access boundary checks. */
   if ((fcu->bezt == NULL) || (active_keyframe_index >= fcu->totvert) ||
       (active_keyframe_index < 0)) {
     return FCURVE_ACTIVE_KEYFRAME_NONE;
   }
 
+  const BezTriple *active_bezt = &fcu->bezt[active_keyframe_index];
+  if ((active_bezt->f2 & SELECT) == 0) {
+    /* The active keyframe should always be selected. If it's not selected, it can't be active. */
+    return FCURVE_ACTIVE_KEYFRAME_NONE;
+  }
+
   return active_keyframe_index;
 }