From 9aa99f226279f6fae80565d346ba9f81d396bd02 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dominik=20R=C3=B6ttsches?= <drott@chromium.org>
Date: Fri, 20 May 2022 17:20:08 +0300
Subject: [PATCH] [truetype] Handle 0xFFFF special value inside delta retrieval
 function

* truetype/ttgxvar.c (tt_hvadvance_adjust, tt_apply_mvar,
tt_var_get_item_delta): Remove special 0xFFFF handling in favor of less
redundant handling inside the tt_var_get_item_delta function, as it is
equivalent to returning a 0 delta. Avoids code-duplication checking for
special value 0xFFFF.
---
 src/truetype/ttgxvar.c | 31 ++++++++++---------------------
 1 file changed, 10 insertions(+), 21 deletions(-)

diff --git a/src/truetype/ttgxvar.c b/src/truetype/ttgxvar.c
index 390e47c83..d6a34e3c5 100644
--- a/src/truetype/ttgxvar.c
+++ b/src/truetype/ttgxvar.c
@@ -972,6 +972,10 @@
     FT_Fixed  scaledDelta;
     FT_Fixed  delta;
 
+    /* OpenType 1.8.4+: No variation data for this item
+     *  as indices have special value 0xFFFF. */
+    if (outerIndex == 0xFFFF && innerIndex == 0xFFFF)
+      return 0;
 
     /* See pseudo code from `Font Variations Overview' */
     /* in the OpenType specification.                  */
@@ -1148,20 +1152,12 @@
       }
     }
 
-    /* new test introduced in OpenType 1.8.4 */
-    if ( outerIndex == 0xFFFFU && innerIndex == 0xFFFFU )
-    {
-      FT_TRACE5(( "no adjustment to %s value %d\n",
-                  vertical ? "vertical height" : "horizontal width",
-                  *avalue ));
-    }
-    else
-    {
-      delta = tt_var_get_item_delta( face,
-                                     &table->itemStore,
-                                     outerIndex,
-                                     innerIndex );
+    delta = tt_var_get_item_delta( face,
+                                   &table->itemStore,
+                                   outerIndex,
+                                   innerIndex );
 
+    if ( delta ) {
       FT_TRACE5(( "%s value %d adjusted by %d unit%s (%s)\n",
                   vertical ? "vertical height" : "horizontal width",
                   *avalue,
@@ -1459,19 +1455,12 @@
       FT_Int     delta;
 
 
-      /* new test introduced in OpenType 1.8.4 */
-      if ( value->outerIndex == 0xFFFFU && value->innerIndex == 0xFFFFU )
-      {
-        /* no variation data for this item */
-        continue;
-      }
-
       delta = tt_var_get_item_delta( face,
                                      &blend->mvar_table->itemStore,
                                      value->outerIndex,
                                      value->innerIndex );
 
-      if ( p )
+      if ( p && delta )
       {
         FT_TRACE5(( "value %c%c%c%c (%d unit%s) adjusted by %d unit%s (MVAR)\n",
                     (FT_Char)( value->tag >> 24 ),