From a854a325a2586ee1d947493036b188acadbaaef2 Mon Sep 17 00:00:00 2001
From: Grigori Goronzy <greg@blackbox>
Date: Tue, 1 Sep 2009 13:31:04 +0200
Subject: Fix underrun in slant pen correction

---
 libass/ass_render.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libass/ass_render.c b/libass/ass_render.c
index fe5114a..de7f045 100644
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -2745,7 +2745,8 @@ ass_render_event(ASS_Renderer *render_priv, ASS_Event *event,
             !render_priv->state.italic) {
             int back = text_info->length - 1;
             GlyphInfo *og = &text_info->glyphs[back];
-            while (og->bbox.xMax - og->bbox.xMin == 0 && og->hash_key.italic)
+            while (back && og->bbox.xMax - og->bbox.xMin == 0
+                   && og->hash_key.italic)
                 og = &text_info->glyphs[--back];
             if (og->bbox.xMax > og->advance.x) {
                 // The FreeType oblique slants by 6/16
-- 
cgit v1.2.3