From eb304c88348fd048b4c057cabb0309dbce808038 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Thu, 8 Nov 2012 19:18:57 +0530
Subject: [PATCH] ...

---
 src/calibre/utils/fonts/sfnt/cff/table.py  |  2 +-
 src/calibre/utils/fonts/sfnt/cff/writer.py | 61 ++++++++++++++++++++--
 2 files changed, 59 insertions(+), 4 deletions(-)

diff --git a/src/calibre/utils/fonts/sfnt/cff/table.py b/src/calibre/utils/fonts/sfnt/cff/table.py
index accb5f91f3..dc1c737461 100644
--- a/src/calibre/utils/fonts/sfnt/cff/table.py
+++ b/src/calibre/utils/fonts/sfnt/cff/table.py
@@ -297,7 +297,7 @@ class CFFTable(UnknownTable):
 
         # Rebuild character_map with the glyph ids from the subset font
         character_map.clear()
-        for code, charname in charset_map:
+        for code, charname in charset_map.iteritems():
             glyph_id = s.charname_map.get(charname, None)
             if glyph_id:
                 character_map[code] = glyph_id
diff --git a/src/calibre/utils/fonts/sfnt/cff/writer.py b/src/calibre/utils/fonts/sfnt/cff/writer.py
index cab5707fa0..c89a0206af 100644
--- a/src/calibre/utils/fonts/sfnt/cff/writer.py
+++ b/src/calibre/utils/fonts/sfnt/cff/writer.py
@@ -7,10 +7,65 @@ __license__   = 'GPL v3'
 __copyright__ = '2012, Kovid Goyal <kovid at kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
+from struct import pack
+from collections import OrderedDict
+
+class Index(list):
+
+    def __init__(self):
+        list.__init__(self)
+        self.raw = None
+
+    def calcsize(self, largest_offset):
+        if largest_offset < 0x100:
+            return 1
+        elif largest_offset < 0x10000:
+            return 2
+        elif largest_offset < 0x1000000:
+            return 3
+        return 4
+
+    def compile(self):
+        if len(self) == 0:
+            self.raw = pack(b'>H', 0)
+        else:
+            offsets = [1]
+            for i, obj in enumerate(self):
+                offsets.append(offsets[-1] + len(obj))
+            offsize = self.calcsize(offsets[-1])
+            obj_data = b''.join(self)
+            prefix = pack(b'>HB', len(self), offsize)
+
+            if offsize == 3:
+                offsets = b''.join(pack(b'>L', x)[1:] for x in offsets)
+            else:
+                fmt = {1:'B', 2:'H', 4:'L'}[offsize]
+                offsets = pack( ('>%d%s'%(len(self), fmt)).encode('ascii'),
+                        *offsets)
+
+            self.raw = prefix + offsets + obj_data
+        return self.raw
+
+
 class Subset(object):
 
-    def __init__(self, cff, character_map):
+    def __init__(self, cff, keep_charnames):
         self.cff = cff
-        self.character_map = character_map
-        self.charname_map = {}
+        self.keep_charnames = keep_charnames
+
+        # Font names Index
+        font_names = Index()
+        font_names.extend(self.cff.font_names)
+
+        # CharStrings Index
+        char_strings = Index()
+        self.charname_map = OrderedDict()
+
+        for i in xrange(self.cff.num_glyphs):
+            cname = self.cff.charset.safe_lookup(i)
+            if cname in keep_charnames:
+                char_strings.append(self.cff.char_strings[i])
+                self.charname_map[cname] = i
+
+        char_strings.compile()