osd: refactor how mp_ass_render_frame() is called

Instead of passing an explicit cache to the function, the res parameter
is used. Also, instead of replacing its contents, sub bitmaps are now
appended to it (all assuming the format doesn't actually change).

This is preparation for the following commits.

1 files changed, 7 insertions, 4 deletions

diff --git a/sub/osd_libass.c b/sub/osd_libass.c
index cd28396746..36fe6ca7d6 100644
--- a/sub/osd_libass.c
+++ b/sub/osd_libass.c
@@ -77,6 +77,7 @@ void osd_destroy_backend(struct osd_state *osd)
         if (obj->osd_ass_library)
             ass_library_done(obj->osd_ass_library);
         obj->osd_ass_library = NULL;
+        talloc_free(obj->parts_cache.parts);
     }
 }
 
@@ -467,13 +468,15 @@ void osd_object_get_bitmaps(struct osd_state *osd, struct osd_object *obj,
     if (obj->force_redraw)
         update_object(osd, obj);
 
-    *out_imgs = (struct sub_bitmaps) {0};
     if (!obj->osd_track)
         return;
 
+    obj->parts_cache.change_id = 0;
+    obj->parts_cache.num_parts = 0;
+
     ass_set_frame_size(obj->osd_render, obj->vo_res.w, obj->vo_res.h);
     ass_set_aspect_ratio(obj->osd_render, obj->vo_res.display_par, 1.0);
-    mp_ass_render_frame(obj->osd_render, obj->osd_track, 0,
-                        &obj->parts_cache, out_imgs);
-    talloc_steal(obj, obj->parts_cache);
+    mp_ass_render_frame(obj->osd_render, obj->osd_track, 0, &obj->parts_cache);
+
+    *out_imgs = obj->parts_cache;
 }