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E-book viewer: Speed up first time open for EPUB files with lots of styling

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The transformation of CSS is now in native code and an order of
magnitude faster. For typical novel length books the total time
for first load processing has been halved.
This commit is contained in:
Kovid Goyal 2021-04-06 13:20:15 +05:30
parent ac68f4550c
commit a62bd36fe4
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GPG Key ID: 06BC317B515ACE7C
1 changed files with 51 additions and 103 deletions
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154
src/calibre/srv/render_book.py
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@ -12,17 +12,12 @@ from collections import defaultdict
from datetime import datetime
from functools import partial
from itertools import count
from math import ceil
from css_parser import replaceUrls
from css_parser.css import CSSRule
from lxml.etree import Comment
from math import ceil
from calibre import detect_ncpus, force_unicode, prepare_string_for_xml
from calibre.constants import iswindows
from calibre.customize.ui import plugin_for_input_format
from calibre.ebooks import parse_css_length
from calibre.ebooks.css_transform_rules import StyleDeclaration
from calibre.ebooks.oeb.base import (
OEB_DOCS, OEB_STYLES, OPF, XHTML, XHTML_NS, XLINK, XPath as _XPath,
rewrite_links, urlunquote
@ -32,7 +27,7 @@ from calibre.ebooks.oeb.polish.container import Container as ContainerBase
from calibre.ebooks.oeb.polish.cover import (
find_cover_image, find_cover_image_in_page, find_cover_page
)
from calibre.ebooks.oeb.polish.css import transform_inline_styles
from calibre.ebooks.oeb.polish.pretty import pretty_script_or_style
from calibre.ebooks.oeb.polish.toc import from_xpaths, get_landmarks, get_toc
from calibre.ebooks.oeb.polish.utils import guess_type
from calibre.ptempfile import PersistentTemporaryDirectory
@ -46,13 +41,14 @@ from calibre.utils.serialize import (
json_dumps, json_loads, msgpack_dumps, msgpack_loads
)
from calibre.utils.short_uuid import uuid4
from calibre_extensions import speedup
from calibre_extensions.fast_css_transform import transform_properties
from polyglot.binary import (
as_base64_unicode as encode_component, from_base64_bytes,
from_base64_unicode as decode_component
)
from polyglot.builtins import as_bytes, iteritems, map, unicode_type
from polyglot.urllib import quote, urlparse
from calibre_extensions import speedup
RENDER_VERSION = 1
@ -85,19 +81,6 @@ def decode_url(x):
return decode_component(parts[0]), (parts[1] if len(parts) > 1 else '')
absolute_units = frozenset('px mm cm pt in pc q'.split())
length_factors = {'mm':2.8346456693, 'cm':28.346456693, 'in': 72, 'pc': 12, 'q':0.708661417325}
def convert_fontsize(length, unit, base_font_size=16.0, dpi=96.0):
' Convert font size to rem so that font size scaling works. Assumes the document has the specified base font size in px '
if unit == 'px':
return length/base_font_size
pt_to_px = dpi / 72.0
pt_to_rem = pt_to_px / base_font_size
return length * length_factors.get(unit, 1) * pt_to_rem
def create_link_replacer(container, link_uid, changed):
resource_template = link_uid + '|{}|'
@ -134,65 +117,6 @@ def create_link_replacer(container, link_uid, changed):
return link_replacer
page_break_properties = ('page-break-before', 'page-break-after', 'page-break-inside')
absolute_font_sizes = {
'xx-small': '0.5rem', 'x-small': '0.625rem', 'small': '0.8rem',
'medium': '1rem',
'large': '1.125rem', 'x-large': '1.5rem', 'xx-large': '2rem', 'xxx-large': '2.55rem'
}
nonstandard_writing_mode_property_names = ('-webkit-writing-mode', '-epub-writing-mode')
def transform_declaration(decl):
decl = StyleDeclaration(decl)
changed = False
nonstandard_writing_mode_props = {}
standard_writing_mode_props = {}
for prop, parent_prop in tuple(decl):
if prop.name in page_break_properties:
changed = True
name = prop.name.partition('-')[2]
for prefix in ('', '-webkit-column-'):
# Note that Firefox does not support break-after at all
# https://bugzil.la/549114
decl.set_property(prefix + name, prop.value, prop.priority)
decl.remove_property(prop, parent_prop)
elif prop.name == 'font-size':
raw = prop.value
afs = absolute_font_sizes.get(raw)
if afs is not None:
changed = True
decl.change_property(prop, parent_prop, afs)
continue
l, unit = parse_css_length(raw)
if unit in absolute_units:
changed = True
l = convert_fontsize(l, unit)
decl.change_property(prop, parent_prop, unicode_type(l) + 'rem')
elif prop.name in nonstandard_writing_mode_property_names:
nonstandard_writing_mode_props[prop.value] = prop.priority
elif prop.name == 'writing-mode':
standard_writing_mode_props[prop.value] = True
# Add standard writing-mode properties if they don't exist so that
# all of the browsers supported by the viewer work in vertical modes
for value, priority in nonstandard_writing_mode_props.items():
if value not in standard_writing_mode_props:
decl.set_property('writing-mode', value, priority)
changed = True
return changed
def transform_sheet(sheet):
changed = False
for rule in sheet.cssRules.rulesOfType(CSSRule.STYLE_RULE):
if transform_declaration(rule.style):
changed = True
return changed
def check_for_maths(root):
for x in root.iterdescendants('{*}math'):
return True
@ -361,27 +285,25 @@ def create_cover_page(container, input_fmt, is_comic, book_metadata=None):
def transform_style_sheet(container, name, link_uid, virtualize_resources, virtualized_names):
changed = False
sheet = container.parsed(name)
link_replacer = None
if virtualize_resources:
changed_names = set()
link_replacer = create_link_replacer(container, link_uid, changed_names)
replaceUrls(sheet, partial(link_replacer, name))
link_replacer = partial(create_link_replacer(container, link_uid, changed_names), name)
if name in changed_names:
changed = True
virtualized_names.add(name)
if transform_sheet(sheet):
raw = container.raw_data(name, decode=True)
nraw = transform_properties(raw, is_declaration=False, url_callback=link_replacer)
if nraw != raw:
changed = True
if changed:
raw = container.serialize_item(name)
else:
raw = container.raw_data(name, decode=False)
raw = nraw
raw = raw.lstrip()
if not raw.startswith(b'@charset'):
raw = b'@charset "UTF-8";\n' + raw
if not raw.startswith('@charset'):
raw = '@charset "UTF-8";\n' + raw
changed = True
if changed:
with container.open(name, 'wb') as f:
f.write(raw)
f.write(raw.encode('utf-8'))
def transform_svg_image(container, name, link_uid, virtualize_resources, virtualized_names):
@ -402,6 +324,26 @@ def transform_svg_image(container, name, link_uid, virtualize_resources, virtual
container.commit_item(name)
def transform_inline_styles(container, name, transform_sheet, transform_style):
root = container.parsed(name)
changed = False
for style in root.xpath('//*[local-name()="style"]'):
if style.text and (style.get('type') or 'text/css').lower() == 'text/css':
nraw = transform_sheet(style.text)
if nraw != style.text:
changed = True
style.text = nraw
pretty_script_or_style(container, style)
for elem in root.xpath('//*[@style]'):
text = elem.get('style', None)
if text:
ntext = transform_style(text)
if ntext != text:
changed = True
elem.set('style', ntext)
return changed
def transform_html(container, name, virtualize_resources, link_uid, link_to_map, virtualized_names):
link_xpath = XPath('//h:a[@href]')
svg_link_xpath = XPath('//svg:a')
@ -425,17 +367,21 @@ def transform_html(container, name, virtualize_resources, link_uid, link_to_map,
if ltype != 'text/css' or rel != 'stylesheet':
link.attrib.clear()
def transform_and_virtualize_sheet(sheet):
changed = transform_sheet(sheet)
if virtualize_resources:
replaceUrls(sheet, partial(link_replacer, name))
if name in changed_names:
virtualized_names.add(name)
changed = True
return changed
# URLs in the inline CSS will be replaced in virtualize_html
def transform_sheet(sheet_text):
ans = transform_properties(sheet_text, is_declaration=False)
if name in changed_names:
virtualized_names.add(name)
return ans
def transform_declaration(decl_text):
ans = transform_properties(decl_text, is_declaration=True)
if name in changed_names:
virtualized_names.add(name)
return ans
# Transform <style> and style=""
transform_inline_styles(container, name, transform_sheet=transform_and_virtualize_sheet, transform_style=transform_declaration)
transform_inline_styles(container, name, transform_sheet=transform_sheet, transform_style=transform_declaration)
if virtualize_resources:
virtualize_html(container, name, link_uid, link_to_map, virtualized_names)
@ -835,8 +781,8 @@ def render(pathtoebook, output_dir, book_hash=None, serialize_metadata=False, ex
with RenderManager(max_workers) as render_manager:
mi = None
if serialize_metadata:
from calibre.ebooks.metadata.meta import get_metadata
from calibre.customize.ui import quick_metadata
from calibre.ebooks.metadata.meta import get_metadata
with lopen(pathtoebook, 'rb') as f, quick_metadata:
mi = get_metadata(f, os.path.splitext(pathtoebook)[1][1:].lower())
book_fmt, opfpath, input_fmt = extract_book(pathtoebook, output_dir, log=default_log)
@ -915,10 +861,12 @@ def develop():
from calibre.ptempfile import TemporaryDirectory
path = sys.argv[-1]
with TemporaryDirectory() as tdir:
return render(
render(
path, tdir, serialize_metadata=True,
extract_annotations=True, virtualize_resources=False, max_workers=1
extract_annotations=True, virtualize_resources=True, max_workers=1
)
print('Extracted to:', tdir)
input('Press Enter to quit')
if __name__ == '__main__':