[truetype] Actually scale varied CVT values.

Up to now, only the unscaled CVT values were varied; in other words,
the `CVAR' data was never used for bytecode hinting.

* src/truetype/ttgxvar.c (tt_cvt_ready_iterator): New auxiliary
function.
(tt_face_vary_cvt): Use it to trigger rescaling of CVT values.

ChangeLog

@@ -1,3 +1,14 @@
+2019-05-16  Werner Lemberg  <wl@gnu.org>
+
+	[truetype] Actually scale varied CVT values.
+
+	Up to now, only the unscaled CVT values were varied; in other words,
+	the `CVAR' data was never used for bytecode hinting.
+
+	* src/truetype/ttgxvar.c (tt_cvt_ready_iterator): New auxiliary
+	function.
+	(tt_face_vary_cvt): Use it to trigger rescaling of CVT values.
+
 2019-05-16  Werner Lemberg  <wl@gnu.org>
 
 	[truetype] Use 26.6 format for storing unscaled CVT values.

docs/CHANGES

@@ -3,6 +3,9 @@ CHANGES BETWEEN 2.10.0 and 2.10.1
 
   I. IMPORTANT BUG FIXES
 
+  - The bytecode hinting of OpenType variation fonts was flawed, since
+    the data in the `CVAR' table wasn't correctly applied.
+
 
   II. MISCELLANEOUS
 
@@ -19,6 +22,9 @@ CHANGES BETWEEN 2.10.0 and 2.10.1
     twice in a row, the function  returned an incorrect error code the
     second time.
 
+  - Increased  precision  while  computing  OpenType  font   variation
+    instances.
+
 
 ======================================================================
 

src/truetype/ttgxvar.c

@@ -3113,6 +3113,21 @@
   /*************************************************************************/
 
 
+  static FT_Error
+  tt_cvt_ready_iterator( FT_ListNode  node,
+                         void*        user )
+  {
+    TT_Size  size = (TT_Size)node->data;
+
+    FT_UNUSED( user );
+
+
+    size->cvt_ready = -1;
+
+    return FT_Err_Ok;
+  }
+
+
   /**************************************************************************
    *
    * @Function:
@@ -3143,6 +3158,8 @@
     FT_Error   error;
     FT_Memory  memory = stream->memory;
 
+    FT_Face  root = &face->root;
+
     FT_ULong  table_start;
     FT_ULong  table_len;
 
@@ -3451,6 +3468,12 @@
     FT_FREE( im_end_coords );
     FT_FREE( cvt_deltas );
 
+    /* iterate over all FT_Size objects and set `cvt_ready' to -1 */
+    /* to trigger rescaling of all CVT values                     */
+    FT_List_Iterate( &root->sizes_list,
+                     tt_cvt_ready_iterator,
+                     NULL );
+
     return error;
   }