Edit book: Remove unused CSS: Add an option to merge CSS rules that have identical properties

src/calibre/ebooks/oeb/polish/css.py

@@ -80,33 +80,38 @@ def merge_identical_properties(sheet):
     properties_map = defaultdict(list)
 
     def declaration_key(declaration):
-        items = []
+        return tuple(sorted(
-        for prop in declaration.getProperties():
+            ((prop.name, prop.propertyValue.value) for prop in declaration.getProperties()),
-            val = prop.propertyValue.value
+            key=itemgetter(0)
-            name = prop.name
+        ))
-            items.append((name, val))
-        items.sort(key=itemgetter(0))
-        return tuple(items)
 
-    for rule in sheet.cssRules.rulesOfType(CSSRule.STYLE_RULE):
+    for idx, rule in enumerate(sheet.cssRules):
-        properties_map[declaration_key(rule.style)].append(rule)
+        if rule.type == CSSRule.STYLE_RULE:
+            properties_map[declaration_key(rule.style)].append((idx, rule))
 
+    removals = []
+    num_merged = 0
     for rule_group in properties_map.values():
         if len(rule_group) < 2:
             continue
-        selectors = rule_group[0].selectorList
+        num_merged += len(rule_group)
+        selectors = rule_group[0][1].selectorList
         seen = {s.selectorText for s in selectors}
         rules = iter(rule_group)
         next(rules)
-        for rule in rules:
+        for idx, rule in rules:
+            removals.append(idx)
             for s in rule.selectorList:
                 q = s.selectorText
                 if q not in seen:
                     seen.add(q)
                     selectors.append(s)
+    for idx in sorted(removals, reverse=True):
+        sheet.cssRules.pop(idx)
+    return num_merged
 
 
-def remove_unused_css(container, report=None, remove_unused_classes=False, merge_rules=False):
+def remove_unused_css(container, report=None, remove_unused_classes=False, merge_rules=False, merge_rules_with_identical_properties=False):
     '''
     Remove all unused CSS rules from the book. An unused CSS rule is one that does not match any actual content.
 
@@ -123,13 +128,19 @@ def remove_unused_css(container, report=None, remove_unused_classes=False, merge
             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
+    num_merged = num_rules_merged = 0
     if merge_rules:
         for name, sheet in iteritems(sheets):
             num = merge_identical_selectors(sheet)
             if num:
                 container.dirty(name)
                 num_merged += num
+    if merge_rules_with_identical_properties:
+        for name, sheet in iteritems(sheets):
+            num = merge_identical_properties(sheet)
+            if num:
+                container.dirty(name)
+                num_rules_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)}
@@ -151,6 +162,11 @@ def remove_unused_css(container, report=None, remove_unused_classes=False, merge
                     if num:
                         num_merged += num
                         container.dirty(name)
+                if merge_rules_with_identical_properties:
+                    num = merge_identical_properties(sheet)
+                    if num:
+                        num_rules_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)
@@ -201,7 +217,7 @@ def remove_unused_css(container, report=None, remove_unused_classes=False, merge
             [sheet.cssRules.remove(r) for r in unused_rules]
             container.dirty(name)
 
-    num_changes = num_of_removed_rules + num_merged + num_of_removed_classes
+    num_changes = num_of_removed_rules + num_merged + num_of_removed_classes + num_rules_merged
     if num_changes > 0:
         if num_of_removed_rules > 0:
             report(ngettext('Removed one unused CSS style rule', 'Removed {} unused CSS style rules',
@@ -210,8 +226,11 @@ def remove_unused_css(container, report=None, remove_unused_classes=False, merge
             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',
+            report(ngettext('Merged one CSS style rule with identical selectors', 'Merged {} CSS style rules with identical selectors',
                             num_merged).format(num_merged))
+        if num_rules_merged > 0:
+            report(ngettext('Merged one CSS style rule with identical properties', 'Merged {} CSS style rules with identical properties',
+                            num_rules_merged).format(num_rules_merged))
     if num_of_removed_rules == 0:
         report(_('No unused CSS style rules found'))
     if remove_unused_classes and num_of_removed_classes == 0:

src/calibre/ebooks/oeb/polish/main.py

@@ -43,6 +43,7 @@ ALL_OPTS = {
 CUSTOMIZATION = {
     'remove_unused_classes': False,
     'merge_identical_selectors': False,
+    'merge_rules_with_identical_properties': False,
 }
 
 SUPPORTED = {'EPUB', 'AZW3'}
@@ -233,7 +234,11 @@ def polish_one(ebook, opts, report, customization=None):
     if opts.remove_unused_css:
         rt(_('Removing unused CSS rules'))
         if remove_unused_css(
-                ebook, report, remove_unused_classes=customization['remove_unused_classes'], merge_rules=customization['merge_identical_selectors']):
+            ebook, report,
+            remove_unused_classes=customization['remove_unused_classes'],
+            merge_rules=customization['merge_identical_selectors'],
+            merge_rules_with_identical_properties=customization['merge_rules_with_identical_properties']
+        ):
             changed = True
         report('')
 

src/calibre/gui2/tweak_book/__init__.py

@@ -53,6 +53,8 @@ d['inline_spell_check'] = True
 d['custom_themes'] = {}
 d['remove_unused_classes'] = False
 d['merge_identical_selectors'] = False
+d['merge_identical_selectors'] = False
+d['merge_rules_with_identical_properties'] = False
 d['global_book_toolbar'] = [
 'new-file', 'open-book',  'save-book', None, 'global-undo', 'global-redo', 'create-checkpoint', None, 'donate', 'user-manual']
 d['global_tools_toolbar'] = [

src/calibre/gui2/tweak_book/polish.py

@@ -54,6 +54,14 @@ def customize_remove_unused_css(name, parent, ans):
         'Merge CSS rules in the same stylesheet that have identical selectors.'
     ' Note that in rare cases merging can result in a change to the effective styling'
     ' of the book, so use with care.'))
+    d.p = p = QCheckBox(_('Merge CSS rules with identical properties'))
+    p.setChecked(tprefs['merge_rules_with_identical_properties'])
+    l.addWidget(p)
+    d.la4 = label('<span style="font-size:small; font-style: italic">' + _(
+        'Merge CSS rules in the same stylesheet that have identical properties.'
+    ' Note that in rare cases merging can result in a change to the effective styling'
+    ' of the book, so use with care.'))
+
     d.bb = QDialogButtonBox(QDialogButtonBox.Ok | QDialogButtonBox.Cancel)
     d.l.addWidget(d.bb)
     d.bb.rejected.connect(d.reject)
@@ -62,6 +70,7 @@ def customize_remove_unused_css(name, parent, ans):
         raise Abort()
     ans['remove_unused_classes'] = tprefs['remove_unused_classes'] = c.isChecked()
     ans['merge_identical_selectors'] = tprefs['merge_identical_selectors'] = m.isChecked()
+    ans['merge_rules_with_identical_properties'] = tprefs['merge_rules_with_identical_properties'] = p.isChecked()
 
 
 def get_customization(action, name, parent):