Fix display of Arabic diacriticals on Windows, per bug #11860.

 src/w32uniscribe.c (uniscribe_shape): Reverse the sign of
 offsets[j].dv, since the y axis of the screen coordinates points
 down, while the y axis of the font definition coordinates points
 up.  This fixes display of Arabic diacritics such as KASRA and
 KASRATAN.

2 files changed, 13 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index a8d6a4026a0..f905cc3b5a2 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2012-09-04  Eli Zaretskii  <eliz@gnu.org>
+
+        * w32uniscribe.c (uniscribe_shape): Reverse the sign of
+        offsets[j].dv, since the y axis of the screen coordinates points
+        down, while the y axis of the font definition coordinates points
+        up.  This fixes display of Arabic diacritics such as KASRA and
+        KASRATAN.  (Bug#11860)
+
 2012-09-04  Paul Eggert  <eggert@cs.ucla.edu>
 
         Be more systematic about _setjmp vs setjmp.
diff --git a/src/w32uniscribe.c b/src/w32uniscribe.c
index bc45e2c648c..cf99d14dc77 100644
--- a/src/w32uniscribe.c
+++ b/src/w32uniscribe.c
@@ -454,7 +454,11 @@ uniscribe_shape (Lisp_Object lgstring)
                         }
                       else
                         ASET (vec, 0, make_number (offsets[j].du + adj_offset));
-                      ASET (vec, 1, make_number (offsets[j].dv));
+                      /* In the font definition coordinate system, the
+                         Y coordinate points up, while in our screen
+                         coordinates Y grows downwards.  So we need to
+                         reverse the sign of Y-OFFSET here.  */
+                      ASET (vec, 1, make_number (-offsets[j].dv));
                       /* Based on what ftfont.c does... */
                       ASET (vec, 2, make_number (advances[j]));
                       LGLYPH_SET_ADJUSTMENT (lglyph, vec);