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PDF Output: Implement font subsetting

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This commit is contained in:
Kovid Goyal 2012-12-20 21:11:01 +05:30
parent 5504db04a9
commit 8436bab0b6
4 changed files with 24 additions and 5 deletions
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2
src/calibre/ebooks/conversion/plumber.py
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@ -1125,7 +1125,7 @@ OptionRecommendation(name='search_replace',
RemoveFakeMargins()(self.oeb, self.log, self.opts)
RemoveAdobeMargins()(self.oeb, self.log, self.opts)
if self.opts.subset_embedded_fonts:
if self.opts.subset_embedded_fonts and self.output_plugin.file_type != 'pdf':
from calibre.ebooks.oeb.transforms.subset import SubsetFonts
SubsetFonts()(self.oeb, self.log, self.opts)

8
src/calibre/ebooks/pdf/render/fonts.py
View File

@ -15,6 +15,7 @@ from future_builtins import map
from calibre.ebooks.pdf.render.common import (Array, String, Stream,
Dictionary, Name)
from calibre.utils.fonts.sfnt.subset import pdf_subset
STANDARD_FONTS = {
'Times-Roman', 'Helvetica', 'Courier', 'Symbol', 'Times-Bold',
@ -152,12 +153,13 @@ class Font(object):
# TODO: Subsetting and OpenType
self.font_descriptor['FontFile2'] = objects.add(self.font_stream)
self.write_widths(objects)
self.write_to_unicode(objects)
glyph_map = self.metrics.sfnt['cmap'].get_char_codes(self.used_glyphs)
self.write_to_unicode(objects, glyph_map)
pdf_subset(self.metrics.sfnt, set(glyph_map))
self.metrics.os2.zero_fstype()
self.metrics.sfnt(self.font_stream)
def write_to_unicode(self, objects):
glyph_map = self.metrics.sfnt['cmap'].get_char_codes(self.used_glyphs)
def write_to_unicode(self, objects, glyph_map):
glyph_map = {k:unicodedata.normalize('NFKC', unichr(v)) for k, v in
glyph_map.iteritems()}
cmap = CMap(self.metrics.postscript_name, glyph_map, compress=self.compress)

2
src/calibre/utils/fonts/sfnt/cff/table.py
View File

@ -194,7 +194,7 @@ class CFFTable(UnknownTable):
glyph_id in character_map.iteritems()}
charset = set(charset_map.itervalues())
charset.discard(None)
if not charset:
if not charset and character_map:
raise NoGlyphs('This font has no glyphs for the specified characters')
charset |= {
self.cff.charset.safe_lookup(glyph_id) for glyph_id in extra_glyphs}

17
src/calibre/utils/fonts/sfnt/subset.py
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@ -81,6 +81,23 @@ def do_warn(warnings, *args):
else:
warnings.append('')
def pdf_subset(sfnt, glyphs):
for tag in tuple(sfnt.tables):
if tag not in {b'hhea', b'head', b'hmtx', b'maxp', b'name',
b'OS/2', b'post', b'cvt', b'fpgm', b'glyf', b'loca',
b'prep', b'CFF ', b'VORG'}:
# Remove non core tables since they are unused in PDF rendering
del sfnt[tag]
if b'loca' in sfnt and b'glyf' in sfnt:
# TrueType Outlines
subset_truetype(sfnt, {}, glyphs)
elif b'CFF ' in sfnt:
# PostScript Outlines
subset_postscript(sfnt, {}, glyphs)
else:
raise UnsupportedFont('This font does not contain TrueType '
'or PostScript outlines')
def subset(raw, individual_chars, ranges=(), warnings=None):
warn = partial(do_warn, warnings)