[type42] Fix glyph access.

This is a severe bug: We've missed one level of indirection, as
described in the Type 42 specification.  As a result, ftview
sometimes showed incorrect glyphs for given glyph names, and even
displayed `error 0x0006' (invalid argument!) in case the number of
glyph indices differed between the Type 42 font and the embedded
TTF.

Apparently, noone ever noticed it; this shows how much Type 42 fonts
are in use...

* src/type42/t42objs.c (T42_GlyphSlot_Load): Map Type 42 glyph index
to embedded TTF's glyph index.

ChangeLog

@@ -1,3 +1,20 @@
+2015-08-08  Werner Lemberg  <wl@gnu.org>
+
+	[type42] Fix glyph access.
+
+	This is a severe bug: We've missed one level of indirection, as
+	described in the Type 42 specification.  As a result, ftview
+	sometimes showed incorrect glyphs for given glyph names, and even
+	displayed `error 0x0006' (invalid argument!) in case the number of
+	glyph indices differed between the Type 42 font and the embedded
+	TTF.
+
+	Apparently, noone ever noticed it; this shows how much Type 42 fonts
+	are in use...
+
+	* src/type42/t42objs.c (T42_GlyphSlot_Load): Map Type 42 glyph index
+	to embedded TTF's glyph index.
+
 2015-08-08  Werner Lemberg  <wl@gnu.org>
 
 	[type42] Minor clean-up.

docs/CHANGES

@@ -8,6 +8,10 @@ CHANGES BETWEEN 2.6 and 2.6.1
       you are  using CFFs; otherwise  you get cropped glyphs  with GUI
       interfaces like GTK or Qt.
 
+    - Accessing Type 42 fonts returned  incorrect results if the glyph
+      order of the embedded TrueType font differs from the glyph order
+      of the Type 42 charstrings table.
+
 
   II. IMPORTANT CHANGES
 
@@ -30,6 +34,15 @@ CHANGES BETWEEN 2.6 and 2.6.1
       don't need any change to the source code.
 
 
+  III. MISCELLANEOUS
+
+    - The auto-hinter's Arabic script support has been enhanced.
+
+    - The TrueType bytecode interpreter now runs slightly faster.
+
+    - Improved support for builds with cmake.
+
+
 ======================================================================
 
 CHANGES BETWEEN 2.5.5 and 2.6

src/type42/t42objs.c

@@ -652,11 +652,16 @@
     FT_Error         error;
     T42_GlyphSlot    t42slot = (T42_GlyphSlot)glyph;
     T42_Size         t42size = (T42_Size)size;
+    T42_Face         t42face = (T42_Face)size->face;
     FT_Driver_Class  ttclazz = ((T42_Driver)glyph->face->driver)->ttclazz;
 
 
     FT_TRACE1(( "T42_GlyphSlot_Load: glyph index %d\n", glyph_index ));
 
+    /* map T42 glyph index to embedded TTF's glyph index */
+    glyph_index = (FT_UInt)ft_atol(
+                    (const char *)t42face->type1.charstrings[glyph_index] );
+
     t42_glyphslot_clear( t42slot->ttslot );
     error = ttclazz->load_glyph( t42slot->ttslot,
                                  t42size->ttsize,