Fix change detection in presence of vector clips

Fixes this test case:

Dialogue: 0,0:00:00.00,0:00:02.00,,,0,0,0,,{\fs50\pos(250,250)\iclip(m 0 0 l 400 0 l 400 220 l0 220)}Hello
Dialogue: 0,0:00:02.00,0:10:00.00,,,0,0,0,,{\fs50\pos(250,250)\iclip(m 0 0 l 400 0 l 400 230 l0 230)}Hello

The problem here is that the rendered output bitmap list itself does
not change, only its contents (due to the different vector clip).
ass_render_frame() will not set *detect_change correctly, and an
application using this flag (like mplayer or mpv) will not update
the screen as needed.

Fix this with a very cheap hack: always report a full change if
there's a vector clip. This is basically an emergency fix until
we have a proper way to detect the change.

1 files changed, 1 insertions, 0 deletions

diff --git a/libass/ass_render.h b/libass/ass_render.h
index 7b3b6d7..f17ad5f 100644
--- a/libass/ass_render.h
+++ b/libass/ass_render.h
@@ -231,6 +231,7 @@ typedef struct {
     ASS_Event *event;
     ASS_Style *style;
     int parsed_tags;
+    int has_vector_clip;
 
     ASS_Font *font;
     double font_size;