Current File : //lib/calibre/calibre/ebooks/oeb/transforms/embed_fonts.py
#!/usr/bin/env python3
__license__ = 'GPL v3'
__copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
import logging
from collections import defaultdict
import css_parser
from lxml import etree
from calibre import guess_type
from calibre.ebooks.oeb.base import XPath, CSS_MIME, XHTML
from calibre.ebooks.oeb.transforms.subset import get_font_properties, find_font_face_rules, elem_style
from calibre.utils.filenames import ascii_filename
from calibre.utils.fonts.scanner import font_scanner, NoFonts
from calibre.ebooks.oeb.polish.embed import font_key
from polyglot.builtins import iteritems
def font_families_from_style(style):
return [str(f) for f in style.get('font-family', []) if str(f).lower() not in {
'serif', 'sansserif', 'sans-serif', 'fantasy', 'cursive', 'monospace'}]
def style_key(style):
style = style.copy()
style['font-family'] = font_families_from_style(style)[0]
return font_key(style)
def font_already_embedded(style, newly_embedded_fonts):
return style_key(style) in newly_embedded_fonts
def used_font(style, embedded_fonts):
ff = font_families_from_style(style)
if not ff:
return False, None
lnames = {str(x).lower() for x in ff}
matching_set = []
# Filter on font-family
for ef in embedded_fonts:
flnames = {x.lower() for x in ef.get('font-family', [])}
if not lnames.intersection(flnames):
continue
matching_set.append(ef)
if not matching_set:
return True, None
# Filter on font-stretch
widths = {x:i for i, x in enumerate(('ultra-condensed',
'extra-condensed', 'condensed', 'semi-condensed', 'normal',
'semi-expanded', 'expanded', 'extra-expanded', 'ultra-expanded'
))}
width = widths[style.get('font-stretch', 'normal')]
for f in matching_set:
f['width'] = widths[style.get('font-stretch', 'normal')]
min_dist = min(abs(width-f['width']) for f in matching_set)
if min_dist > 0:
return True, None
nearest = [f for f in matching_set if abs(width-f['width']) ==
min_dist]
if width <= 4:
lmatches = [f for f in nearest if f['width'] <= width]
else:
lmatches = [f for f in nearest if f['width'] >= width]
matching_set = (lmatches or nearest)
# Filter on font-style
fs = style.get('font-style', 'normal')
matching_set = [f for f in matching_set if f.get('font-style', 'normal') == fs]
# Filter on font weight
fw = int(style.get('font-weight', '400'))
matching_set = [f for f in matching_set if f.get('weight', 400) == fw]
if not matching_set:
return True, None
return True, matching_set[0]
class EmbedFonts:
'''
Embed all referenced fonts, if found on system. Must be called after CSS flattening.
'''
def __call__(self, oeb, log, opts):
self.oeb, self.log, self.opts = oeb, log, opts
self.sheet_cache = {}
self.find_style_rules()
self.find_embedded_fonts()
self.parser = css_parser.CSSParser(loglevel=logging.CRITICAL, log=logging.getLogger('calibre.css'))
self.warned = set()
self.warned2 = set()
self.newly_embedded_fonts = set()
for item in oeb.spine:
if not hasattr(item.data, 'xpath'):
continue
sheets = []
for href in XPath('//h:link[@href and @type="text/css"]/@href')(item.data):
sheet = self.oeb.manifest.hrefs.get(item.abshref(href), None)
if sheet is not None:
sheets.append(sheet)
if sheets:
self.process_item(item, sheets)
def find_embedded_fonts(self):
'''
Find all @font-face rules and extract the relevant info from them.
'''
self.embedded_fonts = []
for item in self.oeb.manifest:
if not hasattr(item.data, 'cssRules'):
continue
self.embedded_fonts.extend(find_font_face_rules(item, self.oeb))
def find_style_rules(self):
'''
Extract all font related style information from all stylesheets into a
dict mapping classes to font properties specified by that class. All
the heavy lifting has already been done by the CSS flattening code.
'''
rules = defaultdict(dict)
for item in self.oeb.manifest:
if not hasattr(item.data, 'cssRules'):
continue
for i, rule in enumerate(item.data.cssRules):
if rule.type != rule.STYLE_RULE:
continue
props = {k:v for k,v in
iteritems(get_font_properties(rule)) if v}
if not props:
continue
for sel in rule.selectorList:
sel = sel.selectorText
if sel and sel.startswith('.'):
# We dont care about pseudo-selectors as the worst that
# can happen is some extra characters will remain in
# the font
sel = sel.partition(':')[0]
rules[sel[1:]].update(props)
self.style_rules = dict(rules)
def get_page_sheet(self):
if self.page_sheet is None:
manifest = self.oeb.manifest
id_, href = manifest.generate('page_css', 'page_styles.css')
self.page_sheet = manifest.add(id_, href, CSS_MIME, data=self.parser.parseString('', validate=False))
head = self.current_item.data.xpath('//*[local-name()="head"][1]')
if head:
href = self.current_item.relhref(href)
l = etree.SubElement(head[0], XHTML('link'),
rel='stylesheet', type=CSS_MIME, href=href)
l.tail = '\n'
else:
self.log.warn('No <head> cannot embed font rules')
return self.page_sheet
def process_item(self, item, sheets):
ff_rules = []
self.current_item = item
self.page_sheet = None
for sheet in sheets:
if 'page_css' in sheet.id:
ff_rules.extend(find_font_face_rules(sheet, self.oeb))
self.page_sheet = sheet
base = {'font-family':['serif'], 'font-weight': '400',
'font-style':'normal', 'font-stretch':'normal'}
for body in item.data.xpath('//*[local-name()="body"]'):
self.find_usage_in(body, base, ff_rules)
def find_usage_in(self, elem, inherited_style, ff_rules):
style = elem_style(self.style_rules, elem.get('class', '') or '', inherited_style)
for child in elem:
self.find_usage_in(child, style, ff_rules)
has_font, existing = used_font(style, ff_rules)
if not has_font or font_already_embedded(style, self.newly_embedded_fonts):
return
if existing is None:
in_book = used_font(style, self.embedded_fonts)[1]
if in_book is None:
# Try to find the font in the system
added = self.embed_font(style)
if added is not None:
self.newly_embedded_fonts.add(style_key(style))
ff_rules.append(added)
self.embedded_fonts.append(added)
else:
# TODO: Create a page rule from the book rule (cannot use it
# directly as paths might be different)
item = in_book['item']
sheet = self.parser.parseString(in_book['rule'].cssText, validate=False)
rule = sheet.cssRules[0]
page_sheet = self.get_page_sheet()
href = page_sheet.abshref(item.href)
rule.style.setProperty('src', 'url(%s)' % href)
ff_rules.append(find_font_face_rules(sheet, self.oeb)[0])
page_sheet.data.insertRule(rule, len(page_sheet.data.cssRules))
def embed_font(self, style):
from calibre.ebooks.oeb.polish.embed import find_matching_font, weight_as_number
ff = font_families_from_style(style)
if not ff:
return
ff = ff[0]
if ff in self.warned or ff == 'inherit':
return
try:
fonts = font_scanner.fonts_for_family(ff)
except NoFonts:
self.log.warn('Failed to find fonts for family:', ff, 'not embedding')
self.warned.add(ff)
return
weight = weight_as_number(style.get('font-weight', '400'))
def do_embed(f):
data = font_scanner.get_font_data(f)
name = f['full_name']
ext = 'otf' if f['is_otf'] else 'ttf'
name = ascii_filename(name).replace(' ', '-').replace('(', '').replace(')', '')
fid, href = self.oeb.manifest.generate(id='font', href='fonts/%s.%s'%(name, ext))
item = self.oeb.manifest.add(fid, href, guess_type('dummy.'+ext)[0], data=data)
item.unload_data_from_memory()
page_sheet = self.get_page_sheet()
href = page_sheet.relhref(item.href)
css = '''@font-face {{ font-family: "{}"; font-weight: {}; font-style: {}; font-stretch: {}; src: url({}) }}'''.format(
f['font-family'], f['font-weight'], f['font-style'], f['font-stretch'], href)
sheet = self.parser.parseString(css, validate=False)
page_sheet.data.insertRule(sheet.cssRules[0], len(page_sheet.data.cssRules))
return find_font_face_rules(sheet, self.oeb)[0]
for f in fonts:
if f['weight'] == weight and f['font-style'] == style.get('font-style', 'normal') and f['font-stretch'] == style.get('font-stretch', 'normal'):
self.log('Embedding font {} from {}'.format(f['full_name'], f['path']))
return do_embed(f)
try:
f = find_matching_font(fonts, style.get('font-weight', 'normal'), style.get('font-style', 'normal'), style.get('font-stretch', 'normal'))
except Exception:
if ff not in self.warned2:
self.log.exception('Failed to find a matching font for family', ff, 'not embedding')
self.warned2.add(ff)
return
self.log('Embedding font {} from {}'.format(f['full_name'], f['path']))
return do_embed(f)
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