[@layer] Cascade @page rules in layer ordering

Bug: 1095765 Change-Id: Iadf69ecc4cde948608409c8b385f937206d8791d Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3188735 Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org> Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org> Cr-Commit-Position: refs/heads/main@{#925799}
FairyWorld · Sep 28, 2021 · 4a2ae1b · 4a2ae1b
1 parent 1ab1858
commit 4a2ae1b
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Showing 8 changed files with 55 additions and 12 deletions.
diff --git a/third_party/blink/renderer/core/css/page_rule_collector.cc b/third_party/blink/renderer/core/css/page_rule_collector.cc
@@ -31,18 +31,14 @@
 #include "third_party/blink/renderer/core/css/page_rule_collector.h"
 
 #include <algorithm>
+#include "third_party/blink/renderer/core/css/cascade_layer_map.h"
 #include "third_party/blink/renderer/core/css/css_property_value_set.h"
 #include "third_party/blink/renderer/core/css/style_rule.h"
 #include "third_party/blink/renderer/core/style/computed_style.h"
 #include "third_party/blink/renderer/platform/wtf/text/atomic_string.h"
 
 namespace blink {
 
-static inline bool ComparePageRules(const StyleRulePage* r1,
-                                    const StyleRulePage* r2) {
-  return r1->Selector()->Specificity() < r2->Selector()->Specificity();
-}
-
 bool PageRuleCollector::IsLeftPage(const ComputedStyle* root_element_style,
                                    uint32_t page_index) const {
   bool is_first_page_left = false;
@@ -68,7 +64,8 @@ PageRuleCollector::PageRuleCollector(const ComputedStyle* root_element_style,
       page_name_(page_name),
       result_(match_result) {}
 
-void PageRuleCollector::MatchPageRules(RuleSet* rules) {
+void PageRuleCollector::MatchPageRules(RuleSet* rules,
+                                       const CascadeLayerMap* layer_map) {
   if (!rules)
     return;
 
@@ -78,8 +75,16 @@ void PageRuleCollector::MatchPageRules(RuleSet* rules) {
   if (matched_page_rules.IsEmpty())
     return;
 
-  std::stable_sort(matched_page_rules.begin(), matched_page_rules.end(),
-                   ComparePageRules);
+  std::stable_sort(
+      matched_page_rules.begin(), matched_page_rules.end(),
+      [layer_map](const StyleRulePage* r1, const StyleRulePage* r2) {
+        if (r1->GetCascadeLayer() != r2->GetCascadeLayer()) {
+          DCHECK(layer_map);
+          return layer_map->CompareLayerOrder(r1->GetCascadeLayer(),
+                                              r2->GetCascadeLayer()) < 0;
+        }
+        return r1->Selector()->Specificity() < r2->Selector()->Specificity();
+      });
 
   for (unsigned i = 0; i < matched_page_rules.size(); i++)
     result_.AddMatchedProperties(&matched_page_rules[i]->Properties());

diff --git a/third_party/blink/renderer/core/css/page_rule_collector.h b/third_party/blink/renderer/core/css/page_rule_collector.h
@@ -28,6 +28,7 @@
 
 namespace blink {
 
+class CascadeLayerMap;
 class StyleRulePage;
 
 class PageRuleCollector {
@@ -39,7 +40,7 @@ class PageRuleCollector {
                     const AtomicString& page_name,
                     MatchResult&);
 
-  void MatchPageRules(RuleSet* rules);
+  void MatchPageRules(RuleSet* rules, const CascadeLayerMap* layer_map);
   const MatchResult& MatchedResult() { return result_; }
 
  private:

diff --git a/third_party/blink/renderer/core/css/resolver/scoped_style_resolver.cc b/third_party/blink/renderer/core/css/resolver/scoped_style_resolver.cc
@@ -292,8 +292,10 @@ void ScopedStyleResolver::CollectMatchingPartPseudoRules(
 void ScopedStyleResolver::MatchPageRules(PageRuleCollector& collector) {
   // Currently, only @page rules in the document scope apply.
   DCHECK(scope_->RootNode().IsDocumentNode());
-  for (auto sheet : style_sheets_)
-    collector.MatchPageRules(&sheet->Contents()->GetRuleSet());
+  for (auto sheet : style_sheets_) {
+    collector.MatchPageRules(&sheet->Contents()->GetRuleSet(),
+                             GetCascadeLayerMap());
+  }
 }
 
 void ScopedStyleResolver::RebuildCascadeLayerMap(

diff --git a/third_party/blink/renderer/core/css/resolver/style_resolver.cc b/third_party/blink/renderer/core/css/resolver/style_resolver.cc
@@ -1121,7 +1121,8 @@ scoped_refptr<const ComputedStyle> StyleResolver::StyleForPage(
                               cascade.MutableMatchResult());
 
   collector.MatchPageRules(
-      CSSDefaultStyleSheets::Instance().DefaultPrintStyle());
+      CSSDefaultStyleSheets::Instance().DefaultPrintStyle(),
+      nullptr /* layer_map */);
 
   if (ScopedStyleResolver* scoped_resolver =
           GetDocument().GetScopedStyleResolver())

diff --git a/third_party/blink/renderer/core/css/resolver/style_resolver_test.cc b/third_party/blink/renderer/core/css/resolver/style_resolver_test.cc
@@ -5,6 +5,7 @@
 #include "third_party/blink/renderer/core/css/resolver/style_resolver.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/blink/public/web/web_print_page_description.h"
 #include "third_party/blink/renderer/bindings/core/v8/v8_union_cssnumericvalue_double.h"
 #include "third_party/blink/renderer/core/animation/animation_test_helpers.h"
 #include "third_party/blink/renderer/core/animation/document_timeline.h"
@@ -24,6 +25,7 @@
 #include "third_party/blink/renderer/core/dom/pseudo_element.h"
 #include "third_party/blink/renderer/core/dom/shadow_root.h"
 #include "third_party/blink/renderer/core/dom/text.h"
+#include "third_party/blink/renderer/core/frame/local_frame.h"
 #include "third_party/blink/renderer/core/html/html_style_element.h"
 #include "third_party/blink/renderer/core/testing/page_test_base.h"
 #include "third_party/blink/renderer/platform/testing/runtime_enabled_features_test_helpers.h"
@@ -1504,4 +1506,30 @@ TEST_F(StyleResolverTest, CascadeLayersInDifferentTreeScopes) {
             &GetDocument());
 }
 
+// TODO(crbug.com/1095765): We should have a WPT for this test case, but
+// currently Blink web test runner can't test @page rules in WPT.
+TEST_F(StyleResolverTest, CascadeLayersAndPageRules) {
+  ScopedCSSCascadeLayersForTest enabled_scope(true);
+
+  GetDocument().documentElement()->setInnerHTML(R"HTML(
+    <style>
+    @layer {
+      @page { margin-top: 100px; }
+    }
+    @page { margin-top: 50px; }
+    </style>
+  )HTML");
+
+  constexpr FloatSize initial_page_size(800, 600);
+
+  GetDocument().GetFrame()->StartPrinting(initial_page_size, initial_page_size);
+  GetDocument().View()->UpdateLifecyclePhasesForPrinting();
+
+  WebPrintPageDescription description;
+  GetDocument().GetPageDescription(0, &description);
+
+  // The layered declaraion should win the cascading.
+  EXPECT_EQ(100, description.margin_top);
+}
+
 }  // namespace blink
diff --git a/third_party/blink/renderer/core/css/rule_set.cc b/third_party/blink/renderer/core/css/rule_set.cc
@@ -407,6 +407,7 @@ void RuleSet::AddChildRules(const HeapVector<Member<StyleRuleBase>>& rules,
         }
       }
     } else if (auto* page_rule = DynamicTo<StyleRulePage>(rule)) {
+      page_rule->SetCascadeLayer(cascade_layer);
       AddPageRule(page_rule);
     } else if (auto* media_rule = DynamicTo<StyleRuleMedia>(rule)) {
       if (MatchMediaForAddRules(medium, media_rule->MediaQueries())) {

diff --git a/third_party/blink/renderer/core/css/style_rule.cc b/third_party/blink/renderer/core/css/style_rule.cc
@@ -370,6 +370,7 @@ MutableCSSPropertyValueSet& StyleRulePage::MutableProperties() {
 
 void StyleRulePage::TraceAfterDispatch(blink::Visitor* visitor) const {
   visitor->Trace(properties_);
+  visitor->Trace(layer_);
   StyleRuleBase::TraceAfterDispatch(visitor);
 }
 

diff --git a/third_party/blink/renderer/core/css/style_rule.h b/third_party/blink/renderer/core/css/style_rule.h
@@ -200,10 +200,14 @@ class StyleRulePage : public StyleRuleBase {
     return MakeGarbageCollected<StyleRulePage>(*this);
   }
 
+  void SetCascadeLayer(const CascadeLayer* layer) { layer_ = layer; }
+  const CascadeLayer* GetCascadeLayer() const { return layer_; }
+
   void TraceAfterDispatch(blink::Visitor*) const;
 
  private:
   Member<CSSPropertyValueSet> properties_;  // Cannot be null.
+  Member<const CascadeLayer> layer_;
   CSSSelectorList selector_list_;
 };