Fix T61234 Mirroring Grease Pencil keyframes in the Dopesheet fails

`ANIM_animdata_update()` did not sort grease pencil frames. A
pre-existing comment stated this wouldn't be necessary as
`posttrans_gpd_clean()` already does this. However, this is only
applicable when the change is performed via the transform system. The
mirror operator doesn't call `posttrans_gpd_clean()`, invalidating the
assumption in the comment.

I moved the sorting code into `BKE_gpencil_layer_frames_sort()`, which
is now called from both `ANIM_animdata_update()` and
`posttrans_gpd_clean()`.

1 files changed, 26 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/gpencil.c b/source/blender/blenkernel/intern/gpencil.c
index c587e433e7f..c0b40721ccc 100644
--- a/source/blender/blenkernel/intern/gpencil.c
+++ b/source/blender/blenkernel/intern/gpencil.c
@@ -1120,6 +1120,32 @@ void BKE_gpencil_layer_mask_sort_all(bGPdata *gpd)
   }
 }
 
+static int gpencil_cb_cmp_frame(void *thunk, const void *a, const void *b)
+{
+  const bGPDframe *frame_a = a;
+  const bGPDframe *frame_b = b;
+
+  if (frame_a->framenum < frame_b->framenum) {
+    return -1;
+  }
+  if (frame_a->framenum > frame_b->framenum) {
+    return 1;
+  }
+  if (thunk != NULL) {
+    *((bool *)thunk) = true;
+  }
+  /* Sort selected last. */
+  if ((frame_a->flag & GP_FRAME_SELECT) && ((frame_b->flag & GP_FRAME_SELECT) == 0)) {
+    return 1;
+  }
+  return 0;
+}
+
+void BKE_gpencil_layer_frames_sort(struct bGPDlayer *gpl, bool *r_has_duplicate_frames)
+{
+  BLI_listbase_sort_r(&gpl->frames, gpencil_cb_cmp_frame, r_has_duplicate_frames);
+}
+
 /* get the active gp-layer for editing */
 bGPDlayer *BKE_gpencil_layer_active_get(bGPdata *gpd)
 {