Fix T92930: Outliner "Show Active" bone fails in certain situations

Outliner would frame the armature object instead of the bone if the bone
was on a hidden armature layer.

Similar to issues reported in e.g. T58068 and T80464, this is due to the
fact that `BKE_pose_channel_active` always checks for the armature layer
(and returns NULL if a bone is not on a visible armature layer).

Now propose to make this layer check **optional** (and e.g. from the
Outliner be more permissive). This also introduces
`BKE_pose_channel_active_if_layer_visible` which just wraps
`BKE_pose_channel_active` with the check being ON.

Maniphest Tasks: T92930

Differential Revision: https://developer.blender.org/D13154

2 files changed, 35 insertions, 7 deletions

diff --git a/source/blender/blenkernel/BKE_action.h b/source/blender/blenkernel/BKE_action.h
index ea8ee3f93b1..5dd98dbb9a3 100644
--- a/source/blender/blenkernel/BKE_action.h
+++ b/source/blender/blenkernel/BKE_action.h
@@ -253,12 +253,28 @@ void BKE_pose_channel_session_uuid_generate(struct bPoseChannel *pchan);
  */
 struct bPoseChannel *BKE_pose_channel_find_name(const struct bPose *pose, const char *name);
 /**
+ * Checks if the bone is on a visible armature layer
+ *
+ * \return true if on a visible layer, false otherwise.
+ */
+bool BKE_pose_is_layer_visible(const struct bArmature *arm, const struct bPoseChannel *pchan);
+/**
  * Find the active pose-channel for an object
- * (we can't just use pose, as layer info is in armature)
  *
- * \note #Object, not #bPose is used here, as we need layer info from Armature.
+ * \param check_arm_layer: checks if the bone is on a visible armature layer (this might be skipped
+ * (e.g. for "Show Active" from the Outliner).
+ * \return #bPoseChannel if found or NULL.
+ * \note #Object, not #bPose is used here, as we need info (layer/active bone) from Armature.
+ */
+struct bPoseChannel *BKE_pose_channel_active(struct Object *ob, const bool check_arm_layer);
+/**
+ * Find the active pose-channel for an object if it is on a visible armature layer
+ * (calls #BKE_pose_channel_active with check_arm_layer set to true)
+ *
+ * \return #bPoseChannel if found or NULL.
+ * \note #Object, not #bPose is used here, as we need info (layer/active bone) from Armature.
  */
-struct bPoseChannel *BKE_pose_channel_active(struct Object *ob);
+struct bPoseChannel *BKE_pose_channel_active_if_layer_visible(struct Object *ob);
 /**
  * Use this when detecting the "other selected bone",
  * when we have multiple armatures in pose mode.
diff --git a/source/blender/blenkernel/intern/action.c b/source/blender/blenkernel/intern/action.c
index ddba726ba83..764c043f5ed 100644
--- a/source/blender/blenkernel/intern/action.c
+++ b/source/blender/blenkernel/intern/action.c
@@ -705,7 +705,12 @@ bool BKE_pose_channels_is_valid(const bPose *pose)
 
 #endif
 
-bPoseChannel *BKE_pose_channel_active(Object *ob)
+bool BKE_pose_is_layer_visible(const bArmature *arm, const bPoseChannel *pchan)
+{
+  return (pchan->bone->layer & arm->layer);
+}
+
+bPoseChannel *BKE_pose_channel_active(Object *ob, const bool check_arm_layer)
 {
   bArmature *arm = (ob) ? ob->data : NULL;
   bPoseChannel *pchan;
@@ -716,14 +721,21 @@ bPoseChannel *BKE_pose_channel_active(Object *ob)
 
   /* find active */
   for (pchan = ob->pose->chanbase.first; pchan; pchan = pchan->next) {
-    if ((pchan->bone) && (pchan->bone == arm->act_bone) && (pchan->bone->layer & arm->layer)) {
-      return pchan;
+    if ((pchan->bone) && (pchan->bone == arm->act_bone)) {
+      if (!check_arm_layer || BKE_pose_is_layer_visible(arm, pchan)) {
+        return pchan;
+      }
     }
   }
 
   return NULL;
 }
 
+bPoseChannel *BKE_pose_channel_active_if_layer_visible(struct Object *ob)
+{
+  return BKE_pose_channel_active(ob, true);
+}
+
 bPoseChannel *BKE_pose_channel_active_or_first_selected(struct Object *ob)
 {
   bArmature *arm = (ob) ? ob->data : NULL;
@@ -732,7 +744,7 @@ bPoseChannel *BKE_pose_channel_active_or_first_selected(struct Object *ob)
     return NULL;
   }
 
-  bPoseChannel *pchan = BKE_pose_channel_active(ob);
+  bPoseChannel *pchan = BKE_pose_channel_active_if_layer_visible(ob);
   if (pchan && (pchan->bone->flag & BONE_SELECTED) && PBONE_VISIBLE(arm, pchan->bone)) {
     return pchan;
   }