From 0b40e8a8642b84591be2021f2316dbcf71919081 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 11 Jan 2013 12:39:20 +0530
Subject: [PATCH] Conversion: When subsetting fonts, handle multiple @font-face
 rules referring to the same physical font

---
 src/calibre/ebooks/oeb/transforms/subset.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/calibre/ebooks/oeb/transforms/subset.py b/src/calibre/ebooks/oeb/transforms/subset.py
index f85f786547..0cca73fcce 100644
--- a/src/calibre/ebooks/oeb/transforms/subset.py
+++ b/src/calibre/ebooks/oeb/transforms/subset.py
@@ -36,7 +36,15 @@ class SubsetFonts(object):
             self.oeb.manifest.remove(font['item'])
             font['rule'].parentStyleSheet.deleteRule(font['rule'])
 
+        fonts = {}
         for font in self.embedded_fonts:
+            item, chars = font['item'], font['chars']
+            if item.href in fonts:
+                fonts[item.href]['chars'] |= chars
+            else:
+                fonts[item.href] = font
+
+        for font in fonts.itervalues():
             if not font['chars']:
                 self.log('The font %s is unused. Removing it.'%font['src'])
                 remove(font)