From ecdb0e35c323ece12a0882444891cfa80552af74 Mon Sep 17 00:00:00 2001
From: Werner Lemberg <wl@gnu.org>
Date: Fri, 3 Jan 2014 20:49:31 +0100
Subject: [PATCH] [autofit] Thinko.

* src/autofit/hbshim.c (af_get_char_index): Similar to
`af_get_coverage', reject glyphs which are not substituted.
---
 ChangeLog             |  7 +++++++
 src/autofit/aflatin.c |  3 +++
 src/autofit/hbshim.c  | 22 +++++++++++++++++++---
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 148e8d9f7..4a6829ab0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2014-01-03  Werner Lemberg  <wl@gnu.org>
+
+	[autofit] Thinko.
+
+	* src/autofit/hbshim.c (af_get_char_index): Similar to
+	`af_get_coverage', reject glyphs which are not substituted.
+
 2014-01-03  Werner Lemberg  <wl@gnu.org>
 
 	[autofit] Fix handling of default coverages.
diff --git a/src/autofit/aflatin.c b/src/autofit/aflatin.c
index 8841d9482..4362bb7fe 100644
--- a/src/autofit/aflatin.c
+++ b/src/autofit/aflatin.c
@@ -89,6 +89,9 @@
                                        [style_class->script];
 
 
+      /* XXX: Extend this with a list of possible standard characters: */
+      /*      Especially in non-default coverages, a singe standard    */
+      /*      character may not be available.                          */
       af_get_char_index( &metrics->root,
                          script_class->standard_char,
                          &glyph_index,
diff --git a/src/autofit/hbshim.c b/src/autofit/hbshim.c
index 844c6bb2e..88c9e48e5 100644
--- a/src/autofit/hbshim.c
+++ b/src/autofit/hbshim.c
@@ -410,10 +410,14 @@
 
     const hb_feature_t*  feature;
 
+    FT_ULong  in_idx, out_idx;
+
 
     if ( !metrics )
       return FT_THROW( Invalid_Argument );
 
+    in_idx = FT_Get_Char_Index( metrics->globals->face, charcode );
+
     style_class = metrics->style_class;
 
     feature = features[style_class->coverage];
@@ -448,8 +452,20 @@
       ginfo = hb_buffer_get_glyph_infos( buf, &gcount );
       gpos  = hb_buffer_get_glyph_positions( buf, &gcount );
 
-      *codepoint = ginfo[0].codepoint;
-      *y_offset  = gpos[0].y_offset;
+      out_idx = ginfo[0].codepoint;
+
+      /* getting the same index indicates no substitution,         */
+      /* which means that the glyph isn't available in the feature */
+      if ( in_idx == out_idx )
+      {
+        *codepoint = 0;
+        *y_offset  = 0;
+      }
+      else
+      {
+        *codepoint = out_idx;
+        *y_offset  = gpos[0].y_offset;
+      }
 
       hb_buffer_destroy( buf );
 
@@ -461,7 +477,7 @@
     }
     else
     {
-      *codepoint = FT_Get_Char_Index( metrics->globals->face, charcode );
+      *codepoint = in_idx;
       *y_offset  = 0;
     }