瀏覽代碼

LibWeb: Implement CSS declaration block's "updating flag"

This flag is used to prevent reparsing the style attribute after it is
automatically updated after using the CSSOM API to mutate style.
Andreas Kling 3 年之前
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a8afb883c1

+ 12 - 0
Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.cpp

@@ -125,10 +125,22 @@ DOM::ExceptionOr<String> PropertyOwningCSSStyleDeclaration::remove_property(Prop
 // https://drafts.csswg.org/cssom/#update-style-attribute-for
 void ElementInlineCSSStyleDeclaration::update_style_attribute()
 {
+    // 1. Assert: declaration block’s computed flag is unset.
+    // NOTE: Unnecessary, only relevant for ResolvedCSSStyleDeclaration.
+
+    // 2. Let owner node be declaration block’s owner node.
+    // 3. If owner node is null, then return.
     if (!m_element)
         return;
 
+    // 4. Set declaration block’s updating flag.
+    m_updating = true;
+
+    // 5. Set an attribute value for owner node using "style" and the result of serializing declaration block.
     m_element->set_attribute(HTML::AttributeNames::style, serialized());
+
+    // 6. Unset declaration block’s updating flag.
+    m_updating = false;
 }
 
 // https://drafts.csswg.org/cssom/#set-a-css-declaration

+ 5 - 0
Userland/Libraries/LibWeb/CSS/CSSStyleDeclaration.h

@@ -101,12 +101,17 @@ public:
     DOM::Element* element() { return m_element.ptr(); }
     const DOM::Element* element() const { return m_element.ptr(); }
 
+    bool is_updating() const { return m_updating; }
+
 private:
     explicit ElementInlineCSSStyleDeclaration(DOM::Element&, Vector<StyleProperty> properties, HashMap<String, StyleProperty> custom_properties);
 
     virtual void update_style_attribute() override;
 
     WeakPtr<DOM::Element> m_element;
+
+    // https://drafts.csswg.org/cssom/#cssstyledeclaration-updating-flag
+    bool m_updating { false };
 };
 
 }

+ 8 - 0
Userland/Libraries/LibWeb/DOM/Element.cpp

@@ -293,6 +293,11 @@ RefPtr<Layout::Node> Element::create_layout_node_for_display_type(DOM::Document&
     TODO();
 }
 
+CSS::CSSStyleDeclaration const* Element::inline_style() const
+{
+    return m_inline_style;
+}
+
 void Element::parse_attribute(FlyString const& name, String const& value)
 {
     if (name == HTML::AttributeNames::class_) {
@@ -305,6 +310,9 @@ void Element::parse_attribute(FlyString const& name, String const& value)
         if (m_class_list)
             m_class_list->associated_attribute_changed(value);
     } else if (name == HTML::AttributeNames::style) {
+        // https://drafts.csswg.org/cssom/#ref-for-cssstyledeclaration-updating-flag
+        if (m_inline_style && m_inline_style->is_updating())
+            return;
         m_inline_style = parse_css_style_attribute(CSS::ParsingContext(document()), value, *this);
         set_needs_style_update(true);
     }

+ 2 - 2
Userland/Libraries/LibWeb/DOM/Element.h

@@ -103,7 +103,7 @@ public:
     void set_computed_css_values(RefPtr<CSS::StyleProperties> style) { m_computed_css_values = move(style); }
     NonnullRefPtr<CSS::StyleProperties> resolved_css_values();
 
-    const CSS::CSSStyleDeclaration* inline_style() const { return m_inline_style; }
+    CSS::CSSStyleDeclaration const* inline_style() const;
 
     NonnullRefPtr<CSS::CSSStyleDeclaration> style_for_bindings();
 
@@ -152,7 +152,7 @@ private:
     String m_html_uppercased_qualified_name;
     NonnullRefPtr<NamedNodeMap> m_attributes;
 
-    RefPtr<CSS::CSSStyleDeclaration> m_inline_style;
+    RefPtr<CSS::ElementInlineCSSStyleDeclaration> m_inline_style;
 
     RefPtr<CSS::StyleProperties> m_computed_css_values;
     HashMap<FlyString, CSS::StyleProperty> m_custom_properties;