Current File : //lib/calibre/calibre/ebooks/oeb/transforms/subset.py
#!/usr/bin/env python3
__license__ = 'GPL v3'
__copyright__ = '2012, Kovid Goyal <kovid at kovidgoyal.net>'
__docformat__ = 'restructuredtext en'
from collections import defaultdict
from calibre.ebooks.oeb.base import urlnormalize, css_text
from calibre.utils.fonts.sfnt.subset import subset, NoGlyphs, UnsupportedFont
from polyglot.builtins import iteritems, itervalues
from tinycss.fonts3 import parse_font_family
def get_font_properties(rule, default=None):
'''
Given a CSS rule, extract normalized font properties from
it. Note that shorthand font property should already have been expanded
by the CSS flattening code.
'''
props = {}
s = rule.style
for q in ('font-family', 'src', 'font-weight', 'font-stretch',
'font-style'):
g = 'uri' if q == 'src' else 'value'
try:
val = s.getProperty(q).propertyValue[0]
val = getattr(val, g)
if q == 'font-family':
val = parse_font_family(css_text(s.getProperty(q).propertyValue))
if val and val[0] == 'inherit':
val = None
except (IndexError, KeyError, AttributeError, TypeError, ValueError):
val = None if q in {'src', 'font-family'} else default
if q in {'font-weight', 'font-stretch', 'font-style'}:
val = str(val).lower() if (val or val == 0) else val
if val == 'inherit':
val = default
if q == 'font-weight':
val = {'normal':'400', 'bold':'700'}.get(val, val)
if val not in {'100', '200', '300', '400', '500', '600', '700',
'800', '900', 'bolder', 'lighter'}:
val = default
if val == 'normal':
val = '400'
elif q == 'font-style':
if val not in {'normal', 'italic', 'oblique'}:
val = default
elif q == 'font-stretch':
if val not in {'normal', 'ultra-condensed', 'extra-condensed',
'condensed', 'semi-condensed', 'semi-expanded',
'expanded', 'extra-expanded', 'ultra-expanded'}:
val = default
props[q] = val
return props
def find_font_face_rules(sheet, oeb):
'''
Find all @font-face rules in the given sheet and extract the relevant info from them.
sheet can be either a ManifestItem or a CSSStyleSheet.
'''
ans = []
try:
rules = sheet.data.cssRules
except AttributeError:
rules = sheet.cssRules
for i, rule in enumerate(rules):
if rule.type != rule.FONT_FACE_RULE:
continue
props = get_font_properties(rule, default='normal')
if not props['font-family'] or not props['src']:
continue
try:
path = sheet.abshref(props['src'])
except AttributeError:
path = props['src']
ff = oeb.manifest.hrefs.get(urlnormalize(path), None)
if not ff:
continue
props['item'] = ff
if props['font-weight'] in {'bolder', 'lighter'}:
props['font-weight'] = '400'
props['weight'] = int(props['font-weight'])
props['rule'] = rule
props['chars'] = set()
ans.append(props)
return ans
def elem_style(style_rules, cls, inherited_style):
'''
Find the effective style for the given element.
'''
classes = cls.split()
style = inherited_style.copy()
for cls in classes:
style.update(style_rules.get(cls, {}))
wt = style.get('font-weight', None)
pwt = inherited_style.get('font-weight', '400')
if wt == 'bolder':
style['font-weight'] = {
'100':'400',
'200':'400',
'300':'400',
'400':'700',
'500':'700',
}.get(pwt, '900')
elif wt == 'lighter':
style['font-weight'] = {
'600':'400', '700':'400',
'800':'700', '900':'700'}.get(pwt, '100')
return style
class SubsetFonts:
'''
Subset all embedded fonts. Must be run after CSS flattening, as it requires
CSS normalization and flattening to work.
'''
def __call__(self, oeb, log, opts):
self.oeb, self.log, self.opts = oeb, log, opts
self.find_embedded_fonts()
if not self.embedded_fonts:
self.log.debug('No embedded fonts found')
return
self.find_style_rules()
self.find_font_usage()
totals = [0, 0]
def remove(font):
totals[1] += len(font['item'].data)
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 itervalues(fonts):
if not font['chars']:
self.log('The font %s is unused. Removing it.'%font['src'])
remove(font)
continue
try:
raw, old_stats, new_stats = subset(font['item'].data, font['chars'])
except NoGlyphs:
self.log('The font %s has no used glyphs. Removing it.'%font['src'])
remove(font)
continue
except UnsupportedFont as e:
self.log.warn('The font %s is unsupported for subsetting. %s'%(
font['src'], e))
sz = len(font['item'].data)
totals[0] += sz
totals[1] += sz
else:
font['item'].data = raw
nlen = sum(itervalues(new_stats))
olen = sum(itervalues(old_stats))
self.log('Decreased the font %s to %.1f%% of its original size'%
(font['src'], nlen/olen *100))
totals[0] += nlen
totals[1] += olen
font['item'].unload_data_from_memory()
if totals[0]:
self.log('Reduced total font size to %.1f%% of original'%
(totals[0]/totals[1] * 100))
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 find_font_usage(self):
for item in self.oeb.manifest:
if not hasattr(item.data, 'xpath'):
continue
for body in item.data.xpath('//*[local-name()="body"]'):
base = {'font-family':['serif'], 'font-weight': '400',
'font-style':'normal', 'font-stretch':'normal'}
self.find_usage_in(body, base)
def used_font(self, style):
'''
Given a style find the embedded font that matches it. Returns None if
no match is found (can happen if no family matches).
'''
ff = style.get('font-family', [])
lnames = {str(x).lower() for x in ff}
matching_set = []
# Filter on font-family
for ef in self.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 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)
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')
order = {
'oblique':['oblique', 'italic', 'normal'],
'normal':['normal', 'oblique', 'italic']
}.get(fs, ['italic', 'oblique', 'normal'])
for q in order:
matches = [f for f in matching_set if f.get('font-style', 'normal') == q]
if matches:
matching_set = matches
break
# Filter on font weight
fw = int(style.get('font-weight', '400'))
if fw == 400:
q = [400, 500, 300, 200, 100, 600, 700, 800, 900]
elif fw == 500:
q = [500, 400, 300, 200, 100, 600, 700, 800, 900]
elif fw < 400:
q = [fw] + list(range(fw-100, -100, -100)) + list(range(fw+100,
100, 1000))
else:
q = [fw] + list(range(fw+100, 100, 1000)) + list(range(fw-100,
-100, -100))
for wt in q:
matches = [f for f in matching_set if f['weight'] == wt]
if matches:
return matches[0]
def find_chars(self, elem):
ans = set()
if elem.text:
ans |= set(elem.text)
for child in elem:
if child.tail:
ans |= set(child.tail)
return ans
def find_usage_in(self, elem, inherited_style):
style = elem_style(self.style_rules, elem.get('class', '') or '', inherited_style)
for child in elem:
self.find_usage_in(child, style)
font = self.used_font(style)
if font:
chars = self.find_chars(elem)
if chars:
font['chars'] |= chars
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