Add todos for missing steps while processing parse font query

components/layout/query.rs

@@ -37,7 +37,7 @@ use std::sync::{Arc, Mutex};
 use style::computed_values::display::T as Display;
 use style::computed_values::position::T as Position;
 use style::computed_values::visibility::T as Visibility;
-use style::context::{StyleContext, ThreadLocalStyleContext};
+use style::context::{QuirksMode, SharedStyleContext, StyleContext, ThreadLocalStyleContext};
 use style::dom::TElement;
 use style::logical_geometry::{BlockFlowDirection, InlineBaseDirection, WritingMode};
 use style::properties::{
@@ -750,28 +750,18 @@ pub fn process_node_scroll_area_request(
     }
 }
 
-pub fn process_parse_font_request<'dom, E>(
-    context: &LayoutContext,
-    node: E,
-    font_value: &str,
+fn create_font_declaration(
+    value: &str,
     property: &PropertyId,
-    url_data: ServoUrl,
-    shared_lock: &SharedRwLock,
-) -> Option<ServoArc<ComputedValues>>
-where
-    E: LayoutNode<'dom>,
-{
-    use style::stylist::RuleInclusion;
-    use style::traversal::resolve_style;
-
-    // 1. Parse the given font property value
-    let quirks_mode = context.style_context.quirks_mode();
+    url_data: &ServoUrl,
+    quirks_mode: QuirksMode,
+) -> Option<PropertyDeclarationBlock> {
     let mut declarations = SourcePropertyDeclaration::new();
     let result = parse_one_declaration_into(
         &mut declarations,
         property.clone(),
-        font_value,
-        &url_data,
+        value,
+        url_data,
         None,
         ParsingMode::DEFAULT,
         quirks_mode,
@@ -784,32 +774,84 @@ where
         },
         Err(_) => return None,
     };
+    // TODO: Force to set line-height property to 'normal' font property.
+    Some(declarations)
+}
+
+fn resolve_for_declarations<'dom, E>(
+    context: &SharedStyleContext,
+    parent_style: Option<&ComputedValues>,
+    declarations: PropertyDeclarationBlock,
+    shared_lock: &SharedRwLock,
+) -> ServoArc<ComputedValues>
+where
+    E: LayoutNode<'dom>,
+{
+    let parent_style = match parent_style {
+        Some(parent) => &*parent,
+        None => context.stylist.device().default_computed_values(),
+    };
+    context
+        .stylist
+        .compute_for_declarations::<E::ConcreteElement>(
+            &context.guards,
+            &*parent_style,
+            ServoArc::new(shared_lock.wrap(declarations)),
+        )
+}
+
+pub fn process_parse_font_request<'dom, E>(
+    context: &LayoutContext,
+    node: E,
+    value: &str,
+    property: &PropertyId,
+    url_data: ServoUrl,
+    shared_lock: &SharedRwLock,
+) -> Option<ServoArc<ComputedValues>>
+where
+    E: LayoutNode<'dom>,
+{
+    use style::stylist::RuleInclusion;
+    use style::traversal::resolve_style;
+
+    // 1. Parse the given font property value
+    let quirks_mode = context.style_context.quirks_mode();
+    let declarations = create_font_declaration(value, property, &url_data, quirks_mode)?;
+
+    // TODO: Reject 'inherit' and 'initial' values for the font property.
 
     // 2. Get resolved styles for the parent element
     let element = node.as_element().unwrap();
-    let parent_style = if element.has_data() {
-        node.to_threadsafe().as_element().unwrap().resolved_style()
+    let parent_style = if node.is_connected() {
+        if element.has_data() {
+            node.to_threadsafe().as_element().unwrap().resolved_style()
+        } else {
+            let mut tlc = ThreadLocalStyleContext::new(&context.style_context);
+            let mut context = StyleContext {
+                shared: &context.style_context,
+                thread_local: &mut tlc,
+            };
+            let styles = resolve_style(&mut context, element, RuleInclusion::All, None);
+            styles.primary().clone()
+        }
     } else {
-        let mut tlc = ThreadLocalStyleContext::new(&context.style_context);
-        let mut context = StyleContext {
-            shared: &context.style_context,
-            thread_local: &mut tlc,
-        };
-        let styles = resolve_style(&mut context, element, RuleInclusion::All, None);
-        styles.primary().clone()
+        let default_declarations =
+            create_font_declaration("10px sans-serif", property, &url_data, quirks_mode).unwrap();
+        resolve_for_declarations::<E>(
+            &context.style_context,
+            None,
+            default_declarations,
+            shared_lock,
+        )
     };
 
     // 3. Resolve the parsed value with resolved styles of the parent element
-    Some(
-        context
-            .style_context
-            .stylist
-            .compute_for_declarations::<E::ConcreteElement>(
-                &context.style_context.guards,
-                &*parent_style,
-                ServoArc::new(shared_lock.wrap(declarations)),
-            ),
-    )
+    Some(resolve_for_declarations::<E>(
+        &context.style_context,
+        Some(&*parent_style),
+        declarations,
+        shared_lock,
+    ))
 }
 
 /// Return the resolved value of property for a given (pseudo)element.

components/script/canvas_state.rs

@@ -22,7 +22,7 @@ use crate::dom::element::Element;
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::htmlcanvaselement::{CanvasContext, HTMLCanvasElement};
 use crate::dom::imagedata::ImageData;
-use crate::dom::node::{Node, NodeDamage};
+use crate::dom::node::{window_from_node, Node, NodeDamage};
 use crate::dom::offscreencanvas::{OffscreenCanvas, OffscreenCanvasContext};
 use crate::dom::paintworkletglobalscope::PaintWorkletGlobalScope;
 use crate::dom::textmetrics::TextMetrics;
@@ -1007,7 +1007,14 @@ impl CanvasState {
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-context-2d-font
-    pub fn set_font(&self, _canvas: Option<&HTMLCanvasElement>, _value: DOMString) {
+    pub fn set_font(&self, canvas: Option<&HTMLCanvasElement>, value: DOMString) {
+        let _resolved_font = if let Some(element) = canvas {
+            let node = element.upcast::<Node>();
+            let window = window_from_node(&*node);
+            window.parse_font_query(&node, value.to_string())
+        } else {
+            None
+        };
         unimplemented!()
     }
 

components/script/dom/window.rs

@@ -1849,9 +1849,6 @@ impl Window {
     }
 
     pub fn parse_font_query(&self, node: &Node, value: String) -> Option<ServoArc<ComputedValues>> {
-        if !node.is_connected() {
-            return None;
-        }
         let id = PropertyId::Shorthand(ShorthandId::Font);
         if !self.layout_reflow(QueryMsg::ParseFontQuery(
             node.to_trusted_node_address(),