ebook-polish: Initial subsetting code

src/calibre/ebooks/oeb/polish/subset.py

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+#!/usr/bin/env python
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:fdm=marker:ai
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+__license__   = 'GPL v3'
+__copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+import os
+
+from calibre.ebooks.oeb.base import OEB_STYLES, OEB_DOCS, XPath
+from calibre.ebooks.oeb.polish import OEB_FONTS
+from calibre.utils.fonts.sfnt.subset import subset
+
+def remove_font_face_rules(container, sheet, remove_names):
+    changed = False
+    for rule in tuple(sheet.cssRules):
+        if rule.type != rule.FONT_FACE_RULE:
+            continue
+        try:
+            uri = rule.style.getProperty('src').propertyValue[0].uri
+        except (IndexError, KeyError, AttributeError, TypeError, ValueError):
+            continue
+        name = container.href_to_name(uri)
+        if name in remove_names:
+            sheet.deleteRule(rule)
+            changed = True
+    return changed
+
+def subset_all_fonts(container, font_stats, report):
+    remove = set()
+    total_old = total_new = 0
+    for name, mt in container.mime_map.iteritems():
+        if mt in OEB_FONTS or name.rpartition('.')[-1].lower() in {'otf', 'ttf'}:
+            chars = font_stats.get(name, set())
+            path = container.name_path_map[name]
+            total_old += os.path.getsize(path)
+            if not chars:
+                remove.add(name)
+                report('Removed unused font: %s'%name)
+                continue
+            with open(path, 'r+b') as f:
+                raw = f.read()
+                warnings = []
+                container.log('Subsetting font: %s'%name)
+                nraw, old_sizes, new_sizes = subset(raw, chars,
+                                                   warnings=warnings)
+                for w in warnings:
+                    container.log.warn(w)
+                olen = sum(old_sizes.itervalues())
+                nlen = sum(new_sizes.itervalues())
+                total_new += len(nraw)
+                report('Decreased the font %s to %.1f%% of its original size'%
+                       (name, nlen/olen * 100))
+                f.seek(0), f.truncate(), f.write(nraw)
+
+    for name in remove:
+        container.remove_item(name)
+
+    if remove:
+        for name, mt in container.mime_map.iteritems():
+            if mt in OEB_STYLES:
+                sheet = container.parsed(name)
+                if remove_font_face_rules(container, sheet, remove):
+                    container.dirty(name)
+            elif mt in OEB_DOCS:
+                for style in XPath('//h:style')(container.parsed(name)):
+                    if style.get('type', 'text/css') == 'text/css' and style.text:
+                        sheet = container.parse_css(style.text, name)
+                        if remove_font_face_rules(container, sheet, remove):
+                            style.text = sheet.cssText
+                            container.dirty(name)
+