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// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/core/css/active_style_sheets.h"
#include "third_party/blink/renderer/core/css/css_style_sheet.h"
#include "third_party/blink/renderer/core/css/resolver/scoped_style_resolver.h"
#include "third_party/blink/renderer/core/css/rule_set.h"
#include "third_party/blink/renderer/core/css/style_change_reason.h"
#include "third_party/blink/renderer/core/css/style_engine.h"
#include "third_party/blink/renderer/core/css/style_sheet_contents.h"
#include "third_party/blink/renderer/core/dom/container_node.h"
namespace blink {
ActiveSheetsChange CompareActiveStyleSheets(
const ActiveStyleSheetVector& old_style_sheets,
const ActiveStyleSheetVector& new_style_sheets,
HeapHashSet<Member<RuleSet>>& changed_rule_sets) {
unsigned new_style_sheet_count = new_style_sheets.size();
unsigned old_style_sheet_count = old_style_sheets.size();
unsigned min_count = std::min(new_style_sheet_count, old_style_sheet_count);
unsigned index = 0;
// Walk the common prefix of stylesheets. If the stylesheet rules were
// modified since last time, add them to the list of changed rulesets.
for (; index < min_count &&
new_style_sheets[index].first == old_style_sheets[index].first;
index++) {
if (new_style_sheets[index].second == old_style_sheets[index].second)
continue;
if (new_style_sheets[index].second)
changed_rule_sets.insert(new_style_sheets[index].second);
if (old_style_sheets[index].second)
changed_rule_sets.insert(old_style_sheets[index].second);
}
// If we add a sheet for which the media attribute currently doesn't match, we
// have a null RuleSet and there's no need to do any style invalidation.
// However, we need to tell the StyleEngine to re-collect viewport and device
// dependent media query results so that we can correctly update active style
// sheets when such media query evaluations change.
bool adds_non_matching_mq = false;
if (index == old_style_sheet_count) {
// The old stylesheet vector is a prefix of the new vector in terms of
// StyleSheets. If none of the RuleSets changed, we only need to add the new
// sheets to the ScopedStyleResolver (ActiveSheetsAppended).
bool rule_sets_changed_in_common_prefix = !changed_rule_sets.IsEmpty();
for (; index < new_style_sheet_count; index++) {
if (new_style_sheets[index].second)
changed_rule_sets.insert(new_style_sheets[index].second);
else if (new_style_sheets[index].first->HasMediaQueryResults())
adds_non_matching_mq = true;
}
if (rule_sets_changed_in_common_prefix)
return kActiveSheetsChanged;
if (changed_rule_sets.IsEmpty() && !adds_non_matching_mq)
return kNoActiveSheetsChanged;
return kActiveSheetsAppended;
}
if (index == new_style_sheet_count) {
// Sheets removed from the end.
for (; index < old_style_sheet_count; index++) {
if (old_style_sheets[index].second)
changed_rule_sets.insert(old_style_sheets[index].second);
else if (old_style_sheets[index].first->HasMediaQueryResults())
adds_non_matching_mq = true;
}
return changed_rule_sets.IsEmpty() && !adds_non_matching_mq
? kNoActiveSheetsChanged
: kActiveSheetsChanged;
}
DCHECK_LT(index, old_style_sheet_count);
DCHECK_LT(index, new_style_sheet_count);
// Both the new and old active stylesheet vectors have stylesheets following
// the common prefix. Figure out which were added or removed by sorting the
// merged vector of old and new sheets.
ActiveStyleSheetVector merged_sorted;
merged_sorted.ReserveCapacity(old_style_sheet_count + new_style_sheet_count -
2 * index);
merged_sorted.AppendRange(old_style_sheets.begin() + index,
old_style_sheets.end());
merged_sorted.AppendRange(new_style_sheets.begin() + index,
new_style_sheets.end());
std::sort(merged_sorted.begin(), merged_sorted.end());
auto* merged_iterator = merged_sorted.begin();
while (merged_iterator != merged_sorted.end()) {
const auto& sheet1 = *merged_iterator++;
if (merged_iterator == merged_sorted.end() ||
(*merged_iterator).first != sheet1.first) {
// Sheet either removed or inserted.
if (sheet1.second)
changed_rule_sets.insert(sheet1.second);
else if (sheet1.first->HasMediaQueryResults())
adds_non_matching_mq = true;
continue;
}
// Sheet present in both old and new.
const auto& sheet2 = *merged_iterator++;
if (sheet1.second == sheet2.second)
continue;
// Active rules for the given stylesheet changed.
// DOM, CSSOM, or media query changes.
if (sheet1.second)
changed_rule_sets.insert(sheet1.second);
if (sheet2.second)
changed_rule_sets.insert(sheet2.second);
}
return changed_rule_sets.IsEmpty() && !adds_non_matching_mq
? kNoActiveSheetsChanged
: kActiveSheetsChanged;
}
bool ClearMediaQueryDependentRuleSets(
const ActiveStyleSheetVector& active_style_sheets) {
bool needs_active_style_update = false;
for (const auto& active_sheet : active_style_sheets) {
if (const MediaQuerySet* media_queries =
active_sheet.first->MediaQueries()) {
if (!media_queries->QueryVector().IsEmpty())
needs_active_style_update = true;
}
StyleSheetContents* contents = active_sheet.first->Contents();
if (contents->HasMediaQueries()) {
needs_active_style_update = true;
contents->ClearRuleSet();
}
}
return needs_active_style_update;
}
} // namespace blink
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