Source code for calibre.ebooks.oeb.polish.css

#!/usr/bin/env python2
# vim:fileencoding=utf-8
from __future__ import absolute_import, division, print_function, unicode_literals

__license__ = 'GPL v3'
__copyright__ = '2014, Kovid Goyal <kovid at>'

from collections import defaultdict
from functools import partial

from css_parser.css import CSSRule, CSSStyleDeclaration
from css_selectors import parse, SelectorSyntaxError

from calibre import force_unicode
from calibre.ebooks.oeb.base import OEB_STYLES, OEB_DOCS, XHTML, css_text
from calibre.ebooks.oeb.normalize_css import normalize_filter_css, normalizers
from calibre.ebooks.oeb.polish.pretty import pretty_script_or_style, pretty_xml_tree, serialize
from import numeric_sort_key
from css_selectors import Select, SelectorError
from polyglot.builtins import iteritems, itervalues, unicode_type, filter
from polyglot.functools import lru_cache

def filter_used_rules(rules, log, select):
    for rule in rules:
        used = False
        for selector in rule.selectorList:
                if select.has_matches(selector.selectorText):
                    used = True
            except SelectorError:
                # Cannot parse/execute this selector, be safe and assume it
                # matches something
                used = True
        if not used:
            yield rule

def get_imported_sheets(name, container, sheets, recursion_level=10, sheet=None):
    ans = set()
    sheet = sheet or sheets[name]
    for rule in sheet.cssRules.rulesOfType(CSSRule.IMPORT_RULE):
        if rule.href:
            iname = container.href_to_name(rule.href, name)
            if iname in sheets:
    if recursion_level > 0:
        for imported_sheet in tuple(ans):
            ans |= get_imported_sheets(imported_sheet, container, sheets, recursion_level=recursion_level-1)
    return ans

def merge_declarations(first, second):
    for prop in second.getProperties():

def merge_identical_selectors(sheet):
    ' Merge rules that have identical selectors '
    selector_map = defaultdict(list)
    for rule in sheet.cssRules.rulesOfType(CSSRule.STYLE_RULE):
    remove = []
    for rule_group in itervalues(selector_map):
        if len(rule_group) > 1:
            for i in range(1, len(rule_group)):
                merge_declarations(rule_group[0].style, rule_group[i].style)
    for rule in remove:
    return len(remove)

[docs]def remove_unused_css(container, report=None, remove_unused_classes=False, merge_rules=False): ''' Remove all unused CSS rules from the book. An unused CSS rule is one that does not match any actual content. :param report: An optional callable that takes a single argument. It is called with information about the operations being performed. :param remove_unused_classes: If True, class attributes in the HTML that do not match any CSS rules are also removed. :param merge_rules: If True, rules with identical selectors are merged. ''' report = report or (lambda x:x) def safe_parse(name): try: return container.parsed(name) except TypeError: pass sheets = {name:safe_parse(name) for name, mt in iteritems(container.mime_map) if mt in OEB_STYLES} sheets = {k:v for k, v in iteritems(sheets) if v is not None} num_merged = 0 if merge_rules: for name, sheet in iteritems(sheets): num = merge_identical_selectors(sheet) if num: container.dirty(name) num_merged += num import_map = {name:get_imported_sheets(name, container, sheets) for name in sheets} if remove_unused_classes: class_map = {name:{icu_lower(x) for x in classes_in_rule_list(sheet.cssRules)} for name, sheet in iteritems(sheets)} style_rules = {name:tuple(sheet.cssRules.rulesOfType(CSSRule.STYLE_RULE)) for name, sheet in iteritems(sheets)} num_of_removed_rules = num_of_removed_classes = 0 for name, mt in iteritems(container.mime_map): if mt not in OEB_DOCS: continue root = container.parsed(name) select = Select(root, ignore_inappropriate_pseudo_classes=True) used_classes = set() for style in root.xpath('//*[local-name()="style"]'): if style.get('type', 'text/css') == 'text/css' and style.text: sheet = container.parse_css(style.text) if merge_rules: num = merge_identical_selectors(sheet) if num: num_merged += num container.dirty(name) if remove_unused_classes: used_classes |= {icu_lower(x) for x in classes_in_rule_list(sheet.cssRules)} imports = get_imported_sheets(name, container, sheets, sheet=sheet) for imported_sheet in imports: style_rules[imported_sheet] = tuple(filter_used_rules(style_rules[imported_sheet], container.log, select)) if remove_unused_classes: used_classes |= class_map[imported_sheet] rules = tuple(sheet.cssRules.rulesOfType(CSSRule.STYLE_RULE)) unused_rules = tuple(filter_used_rules(rules, container.log, select)) if unused_rules: num_of_removed_rules += len(unused_rules) [sheet.cssRules.remove(r) for r in unused_rules] style.text = force_unicode(sheet.cssText, 'utf-8') pretty_script_or_style(container, style) container.dirty(name) for link in root.xpath('//*[local-name()="link" and @href]'): sname = container.href_to_name(link.get('href'), name) if sname not in sheets: continue style_rules[sname] = tuple(filter_used_rules(style_rules[sname], container.log, select)) if remove_unused_classes: used_classes |= class_map[sname] for iname in import_map[sname]: style_rules[iname] = tuple(filter_used_rules(style_rules[iname], container.log, select)) if remove_unused_classes: used_classes |= class_map[iname] if remove_unused_classes: for elem in root.xpath('//*[@class]'): original_classes, classes = elem.get('class', '').split(), [] for x in original_classes: if icu_lower(x) in used_classes: classes.append(x) if len(classes) != len(original_classes): if classes: elem.set('class', ' '.join(classes)) else: del elem.attrib['class'] num_of_removed_classes += len(original_classes) - len(classes) container.dirty(name) for name, sheet in iteritems(sheets): unused_rules = style_rules[name] if unused_rules: num_of_removed_rules += len(unused_rules) [sheet.cssRules.remove(r) for r in unused_rules] container.dirty(name) num_changes = num_of_removed_rules + num_merged + num_of_removed_classes if num_changes > 0: if num_of_removed_rules > 0: report(ngettext('Removed one unused CSS style rule', 'Removed {} unused CSS style rules', num_of_removed_rules).format(num_of_removed_rules)) if num_of_removed_classes > 0: report(ngettext('Removed one unused class from the HTML', 'Removed {} unused classes from the HTML', num_of_removed_classes).format(num_of_removed_classes)) if num_merged > 0: report(ngettext('Merged one CSS style rule', 'Merged {} CSS style rules', num_merged).format(num_merged)) if num_of_removed_rules == 0: report(_('No unused CSS style rules found')) if remove_unused_classes and num_of_removed_classes == 0: report(_('No unused class attributes found')) if merge_rules and num_merged == 0: report(_('No style rules that could be merged found')) return num_changes > 0
def filter_declaration(style, properties=()): changed = False for prop in properties: if style.removeProperty(prop) != '': changed = True all_props = set(style.keys()) for prop in style.getProperties(): n = normalizers.get(, None) if n is not None: normalized = n(, prop.propertyValue) removed = properties.intersection(set(normalized)) if removed: changed = True style.removeProperty( for prop in set(normalized) - removed - all_props: style.setProperty(prop, normalized[prop]) return changed def filter_sheet(sheet, properties=()): from css_parser.css import CSSRule changed = False remove = [] for rule in sheet.cssRules.rulesOfType(CSSRule.STYLE_RULE): if filter_declaration(, properties): changed = True if == 0: remove.append(rule) for rule in remove: sheet.cssRules.remove(rule) return changed 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': sheet = container.parse_css(style.text) if transform_sheet(sheet): changed = True style.text = force_unicode(sheet.cssText, 'utf-8') pretty_script_or_style(container, style) for elem in root.xpath('//*[@style]'): text = elem.get('style', None) if text: style = container.parse_css(text, is_declaration=True) if transform_style(style): changed = True if style.length == 0: del elem.attrib['style'] else: elem.set('style', force_unicode(style.getCssText(separator=' '), 'utf-8')) return changed def transform_css(container, transform_sheet=None, transform_style=None, names=()): if not names: types = OEB_STYLES | OEB_DOCS names = [] for name, mt in iteritems(container.mime_map): if mt in types: names.append(name) doc_changed = False for name in names: mt = container.mime_map[name] if mt in OEB_STYLES: sheet = container.parsed(name) if transform_sheet(sheet): container.dirty(name) doc_changed = True elif mt in OEB_DOCS: if transform_inline_styles(container, name, transform_sheet, transform_style): container.dirty(name) doc_changed = True return doc_changed
[docs]def filter_css(container, properties, names=()): ''' Remove the specified CSS properties from all CSS rules in the book. :param properties: Set of properties to remove. For example: :code:`{'font-family', 'color'}`. :param names: The files from which to remove the properties. Defaults to all HTML and CSS files in the book. ''' properties = normalize_filter_css(properties) return transform_css(container, transform_sheet=partial(filter_sheet, properties=properties), transform_style=partial(filter_declaration, properties=properties), names=names)
def _classes_in_selector(selector, classes): for attr in ('selector', 'subselector', 'parsed_tree'): s = getattr(selector, attr, None) if s is not None: _classes_in_selector(s, classes) cn = getattr(selector, 'class_name', None) if cn is not None: classes.add(cn) @lru_cache(maxsize=4096) def classes_in_selector(text): classes = set() try: for selector in parse(text): _classes_in_selector(selector, classes) except SelectorSyntaxError: pass return classes def classes_in_rule_list(css_rules): classes = set() for rule in css_rules: if rule.type == rule.STYLE_RULE: classes |= classes_in_selector(rule.selectorText) elif hasattr(rule, 'cssRules'): classes |= classes_in_rule_list(rule.cssRules) return classes def iter_declarations(sheet_or_rule): if hasattr(sheet_or_rule, 'cssRules'): for rule in sheet_or_rule.cssRules: for x in iter_declarations(rule): yield x elif hasattr(sheet_or_rule, 'style'): yield elif isinstance(sheet_or_rule, CSSStyleDeclaration): yield sheet_or_rule def remove_property_value(prop, predicate): ''' Remove the Values that match the predicate from this property. If all values of the property would be removed, the property is removed from its parent instead. Note that this means the property must have a parent (a CSSStyleDeclaration). ''' removed_vals = list(filter(predicate, prop.propertyValue)) if len(removed_vals) == len(prop.propertyValue): prop.parent.removeProperty( else: x = css_text(prop.propertyValue) for v in removed_vals: x = x.replace(css_text(v), '').strip() prop.propertyValue.cssText = x return bool(removed_vals) RULE_PRIORITIES = {t:i for i, t in enumerate((CSSRule.COMMENT, CSSRule.CHARSET_RULE, CSSRule.IMPORT_RULE, CSSRule.NAMESPACE_RULE))} def sort_sheet(container, sheet_or_text): ''' Sort the rules in a stylesheet. Note that in the general case this can change the effective styles, but for most common sheets, it should be safe. ''' sheet = container.parse_css(sheet_or_text) if isinstance(sheet_or_text, unicode_type) else sheet_or_text def text_sort_key(x): return numeric_sort_key(unicode_type(x or '')) def selector_sort_key(x): return (x.specificity, text_sort_key(x.selectorText)) def rule_sort_key(rule): primary = RULE_PRIORITIES.get(rule.type, len(RULE_PRIORITIES)) secondary = text_sort_key(getattr(rule, 'atkeyword', '') or '') tertiary = None if rule.type == CSSRule.STYLE_RULE: primary += 1 selectors = sorted(rule.selectorList, key=selector_sort_key) tertiary = selector_sort_key(selectors[0]) rule.selectorText = ', '.join(s.selectorText for s in selectors) elif rule.type == CSSRule.FONT_FACE_RULE: try: tertiary = text_sort_key('font-family')) except Exception: pass return primary, secondary, tertiary sheet.cssRules.sort(key=rule_sort_key) return sheet def add_stylesheet_links(container, name, text): root = container.parse_xhtml(text, name) head = root.xpath('//*[local-name() = "head"]') if not head: return head = head[0] sheets = tuple(container.manifest_items_of_type(lambda mt: mt in OEB_STYLES)) if not sheets: return for sname in sheets: link = head.makeelement(XHTML('link'), type='text/css', rel='stylesheet', href=container.name_to_href(sname, name)) head.append(link) pretty_xml_tree(head) return serialize(root, 'text/html')