Implement CanvasRenderingContext2D.font property

components/layout/query.rs

@@ -90,6 +90,9 @@ pub struct LayoutThreadData {
 
     /// A queued response for the viewport dimensions for a given browsing context.
     pub inner_window_dimensions_response: Option<TypedSize2D<f32, CSSPixel>>,
+
+    /// A queued response for the resolved font property of a canvas element.
+    pub canvas_font_response: String,
 }
 
 pub struct LayoutRPCImpl(pub Arc<Mutex<LayoutThreadData>>);
@@ -1095,3 +1098,11 @@ fn is_last_table_row() -> bool {
     // FIXME(ferjm) Implement this.
     false
 }
+
+pub fn process_canvas_font_request<'dom>(
+    _node: impl LayoutNode<'dom>,
+    _font: &str,
+    _layout_root: &mut dyn Flow,
+) -> String {
+    unimplemented!()
+}

components/layout_thread/lib.rs

@@ -50,12 +50,14 @@ use layout::flow_ref::FlowRef;
 use layout::incremental::{RelayoutMode, SpecialRestyleDamage};
 use layout::layout_debug;
 use layout::parallel;
+use layout::query::{
+    process_canvas_font_request, process_offset_parent_query, process_resolved_style_request,
+};
 use layout::query::{process_client_rect_query, process_element_inner_text_query};
 use layout::query::{
     process_content_box_request, process_content_boxes_request, LayoutRPCImpl, LayoutThreadData,
 };
 use layout::query::{process_node_scroll_area_request, process_node_scroll_id_request};
-use layout::query::{process_offset_parent_query, process_resolved_style_request};
 use layout::sequential;
 use layout::traversal::{
     ComputeStackingRelativePositions, PreorderFlowTraversal, RecalcStyleAndConstructFlows,
@@ -575,6 +577,7 @@ impl LayoutThread {
                 nodes_from_point_response: vec![],
                 element_inner_text_response: String::new(),
                 inner_window_dimensions_response: None,
+                canvas_font_response: String::new(),
             })),
             webrender_image_cache: Arc::new(RwLock::new(FnvHashMap::default())),
             paint_time_metrics: paint_time_metrics,
@@ -1255,6 +1258,9 @@ impl LayoutThread {
                         &QueryMsg::InnerWindowDimensionsQuery(_) => {
                             rw_data.inner_window_dimensions_response = None;
                         },
+                        &QueryMsg::CanvasFontQuery(..) => {
+                            unimplemented!();
+                        },
                     },
                     ReflowGoal::Full | ReflowGoal::TickAnimations => {},
                 }
@@ -1597,6 +1603,11 @@ impl LayoutThread {
                         .get(&browsing_context_id)
                         .cloned();
                 },
+                &QueryMsg::CanvasFontQuery(node, ref font) => {
+                    let node = unsafe { ServoLayoutNode::new(&node) };
+                    rw_data.canvas_font_response =
+                        process_canvas_font_request(node, font, root_flow);
+                },
             },
             ReflowGoal::Full | ReflowGoal::TickAnimations => {},
         }

components/script/canvas_state.rs

@@ -49,6 +49,12 @@ use std::cell::Cell;
 use std::fmt;
 use std::str::FromStr;
 use std::sync::Arc;
+use style::context::QuirksMode;
+use style::parser::ParserContext;
+use style::properties::shorthands::font;
+use style::stylesheets::origin::Origin;
+use style::stylesheets::CssRuleType;
+use style_traits::ParsingMode;
 
 #[unrooted_must_root_lint::must_root]
 #[derive(Clone, JSTraceable, MallocSizeOf)]
@@ -1558,6 +1564,30 @@ impl CanvasState {
         ));
         Ok(())
     }
+
+    // https://html.spec.whatwg.org/multipage/#dom-context-2d-font
+    pub fn font(&self) -> DOMString {
+        unimplemented!()
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-context-2d-font
+    pub fn set_font(&self, value: DOMString) {
+        let mut input = ParserInput::new(&value);
+        let mut parser = Parser::new(&mut input);
+        let context = ParserContext::new(
+            Origin::Author,
+            &self.base_url,
+            Some(CssRuleType::Style),
+            ParsingMode::DEFAULT,
+            QuirksMode::NoQuirks,
+            None,
+            None,
+        );
+        match font::parse_value(&context, &mut parser) {
+            Ok(_longhands) => unimplemented!("TODO: handle parsed values"),
+            Err(_err) => unimplemented!("TODO: handle parse errors"),
+        }
+    }
 }
 
 pub fn parse_color(string: &str) -> Result<RGBA, ()> {

components/script/dom/canvasrenderingcontext2d.rs

@@ -606,6 +606,16 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
     fn SetShadowColor(&self, value: DOMString) {
         self.canvas_state.set_shadow_color(value)
     }
+
+    // https://html.spec.whatwg.org/multipage/#dom-context-2d-font
+    fn Font(&self) -> DOMString {
+        self.canvas_state.font()
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-context-2d-font
+    fn SetFont(&self, value: DOMString) {
+        self.canvas_state.set_font(value)
+    }
 }
 
 impl Drop for CanvasRenderingContext2D {

components/script/dom/offscreencanvasrenderingcontext2d.rs

@@ -513,4 +513,14 @@ impl OffscreenCanvasRenderingContext2DMethods for OffscreenCanvasRenderingContex
         self.canvas_state
             .ellipse(x, y, rx, ry, rotation, start, end, ccw)
     }
+
+    // https://html.spec.whatwg.org/multipage/#dom-context-2d-font
+    fn Font(&self) -> DOMString {
+        self.canvas_state.font()
+    }
+
+    // https://html.spec.whatwg.org/multipage/#dom-context-2d-font
+    fn SetFont(&self, value: DOMString) {
+        self.canvas_state.set_font(value)
+    }
 }

components/script/dom/webidls/CanvasRenderingContext2D.webidl

@@ -211,7 +211,7 @@ interface mixin CanvasPathDrawingStyles {
 [Exposed=(PaintWorklet, Window, Worker)]
 interface mixin CanvasTextDrawingStyles {
   // text
-  //attribute DOMString font; // (default 10px sans-serif)
+  attribute DOMString font; // (default 10px sans-serif)
   //attribute CanvasTextAlign textAlign; // "start", "end", "left", "right", "center" (default: "start")
   //attribute CanvasTextBaseline textBaseline; // "top", "hanging", "middle", "alphabetic",
                                       // "ideographic", "bottom" (default: "alphabetic")

components/script/dom/window.rs

@@ -2460,6 +2460,7 @@ fn debug_reflow_events(id: PipelineId, reflow_goal: &ReflowGoal, reason: &Reflow
             &QueryMsg::TextIndexQuery(..) => "\tTextIndexQuery",
             &QueryMsg::ElementInnerTextQuery(_) => "\tElementInnerTextQuery",
             &QueryMsg::InnerWindowDimensionsQuery(_) => "\tInnerWindowDimensionsQuery",
+            &QueryMsg::CanvasFontQuery(..) => "\tCanvasFontQuery",
         },
     };
 

components/script_layout_interface/message.rs

@@ -116,6 +116,7 @@ pub enum QueryMsg {
     StyleQuery,
     ElementInnerTextQuery(TrustedNodeAddress),
     InnerWindowDimensionsQuery(BrowsingContextId),
+    CanvasFontQuery(TrustedNodeAddress, String),
 }
 
 /// Any query to perform with this reflow.
@@ -144,6 +145,7 @@ impl ReflowGoal {
                 QueryMsg::NodeScrollIdQuery(_) |
                 QueryMsg::ResolvedStyleQuery(..) |
                 QueryMsg::OffsetParentQuery(_) |
+                QueryMsg::CanvasFontQuery(..) |
                 QueryMsg::StyleQuery => false,
             },
         }
@@ -166,6 +168,7 @@ impl ReflowGoal {
                 QueryMsg::ResolvedStyleQuery(..) |
                 QueryMsg::OffsetParentQuery(_) |
                 QueryMsg::InnerWindowDimensionsQuery(_) |
+                QueryMsg::CanvasFontQuery(..) |
                 QueryMsg::StyleQuery => false,
             },
         }