From e6438cc29c441ed6d0aad17dc6bdd85b69ced61b Mon Sep 17 00:00:00 2001
From: Grigori Goronzy <greg@blackbox>
Date: Mon, 16 May 2011 02:04:38 +0200
Subject: Match first occurence of \fade, \fad, \an and \a tags

Track if we already parsed a fade or a alignment tag and ignore all
further tags.
---
 libass/ass_parse.c  | 27 ++++++++++++++++++---------
 libass/ass_render.c |  1 +
 libass/ass_render.h |  4 ++++
 3 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/libass/ass_parse.c b/libass/ass_parse.c
index 40aaf04..55e8fd1 100644
--- a/libass/ass_parse.c
+++ b/libass/ass_parse.c
@@ -503,16 +503,22 @@ static char *parse_tag(ASS_Renderer *render_priv, char *p, double pwr)
             val = ((val - 1) % 3) + 1;  // horizontal alignment
             val += v * 4;
             ass_msg(render_priv->library, MSGL_DBG2, "align %d", val);
-            render_priv->state.alignment = val;
+            if ((render_priv->state.parsed_tags & PARSED_A) == 0) {
+                render_priv->state.alignment = val;
+                render_priv->state.parsed_tags |= PARSED_A;
+            }
         } else
             render_priv->state.alignment =
                 render_priv->state.style->Alignment;
     } else if (mystrcmp(&p, "a")) {
         int val;
-        if (mystrtoi(&p, &val) && val)
-            // take care of a vsfilter quirk: handle illegal \a8 like \a5
-            render_priv->state.alignment = (val == 8) ? 5 : val;
-        else
+        if (mystrtoi(&p, &val) && val) {
+            if ((render_priv->state.parsed_tags & PARSED_A) == 0) {
+                // take care of a vsfilter quirk: handle illegal \a8 like \a5
+                render_priv->state.alignment = (val == 8) ? 5 : val;
+                render_priv->state.parsed_tags |= PARSED_A;
+            }
+        } else
             render_priv->state.alignment =
                 render_priv->state.style->Alignment;
     } else if (mystrcmp(&p, "pos")) {
@@ -566,10 +572,13 @@ static char *parse_tag(ASS_Renderer *render_priv, char *p, double pwr)
             mystrtoll(&p, &t4);
         }
         skip(')');
-        render_priv->state.fade =
-            interpolate_alpha(render_priv->time -
-                              render_priv->state.event->Start, t1, t2,
-                              t3, t4, a1, a2, a3);
+        if ((render_priv->state.parsed_tags & PARSED_FADE) == 0) {
+            render_priv->state.fade =
+                interpolate_alpha(render_priv->time -
+                        render_priv->state.event->Start, t1, t2,
+                        t3, t4, a1, a2, a3);
+            render_priv->state.parsed_tags |= PARSED_FADE;
+        }
     } else if (mystrcmp(&p, "org")) {
         int v1, v2;
         skip('(');
diff --git a/libass/ass_render.c b/libass/ass_render.c
index 2f3405e..0db6303 100644
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -887,6 +887,7 @@ init_render_context(ASS_Renderer *render_priv, ASS_Event *event)
 {
     render_priv->state.event = event;
     render_priv->state.style = render_priv->track->styles + event->Style;
+    render_priv->state.parsed_tags = 0;
 
     reset_render_context(render_priv);
 
diff --git a/libass/ass_render.h b/libass/ass_render.h
index 89bffb0..78c7339 100644
--- a/libass/ass_render.h
+++ b/libass/ass_render.h
@@ -39,6 +39,9 @@
 #define GLYPH_CACHE_MAX 1000
 #define BITMAP_CACHE_MAX_SIZE 30 * 1048576
 
+#define PARSED_FADE (1<<0)
+#define PARSED_A    (1<<1)
+
 typedef struct {
     double xMin;
     double xMax;
@@ -141,6 +144,7 @@ typedef struct {
 typedef struct {
     ASS_Event *event;
     ASS_Style *style;
+    int parsed_tags;
 
     ASS_Font *font;
     char *font_path;
-- 
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