Implement CanvasRenderingContext2D.font property

Cargo.lock

@@ -515,6 +515,7 @@ dependencies = [
  "raqote",
  "servo_config",
  "sparkle",
+ "style",
  "surfman",
  "surfman-chains",
  "surfman-chains-api",
@@ -542,6 +543,7 @@ dependencies = [
  "serde_bytes",
  "servo_config",
  "sparkle",
+ "style",
  "time",
  "webrender_api",
  "webxr-api",

components/canvas/Cargo.toml

@@ -34,6 +34,7 @@ pixels = { path = "../pixels" }
 raqote = { version = "0.8", features = ["text"] }
 servo_config = { path = "../config" }
 sparkle = "0.1.24"
+style = { path = "../style" }
 # NOTE: the sm-angle feature only enables ANGLE on Windows, not other platforms!
 surfman = { version = "0.2", features = ["sm-angle", "sm-angle-default"] }
 surfman-chains = "0.3"

components/canvas/canvas_data.rs

@@ -13,6 +13,7 @@ use num_traits::ToPrimitive;
 use std::marker::PhantomData;
 use std::mem;
 use std::sync::Arc;
+use style::properties::style_structs::Font as FontStyleStruct;
 use webrender_api::units::RectExt as RectExt_;
 
 /// The canvas data stores a state machine for the current status of
@@ -1067,6 +1068,10 @@ impl<'a> CanvasData<'a> {
         self.backend.set_shadow_color(value, &mut self.state);
     }
 
+    pub fn set_font(&mut self, font_style: FontStyleStruct) {
+        self.state.font_style = Some(font_style)
+    }
+
     // https://html.spec.whatwg.org/multipage/#when-shadows-are-drawn
     fn need_to_draw_shadow(&self) -> bool {
         self.backend.need_to_draw_shadow(&self.state.shadow_color) &&
@@ -1158,6 +1163,7 @@ pub struct CanvasPaintState<'a> {
     pub shadow_offset_y: f64,
     pub shadow_blur: f64,
     pub shadow_color: Color,
+    pub font_style: Option<FontStyleStruct>,
 }
 
 /// It writes an image to the destination target

components/canvas/canvas_paint_thread.rs

@@ -247,6 +247,7 @@ impl<'a> CanvasPaintThread<'a> {
             },
             Canvas2dMsg::SetShadowBlur(value) => self.canvas(canvas_id).set_shadow_blur(value),
             Canvas2dMsg::SetShadowColor(color) => self.canvas(canvas_id).set_shadow_color(color),
+            Canvas2dMsg::SetFont(font_style) => self.canvas(canvas_id).set_font(font_style),
         }
     }
 

components/canvas/raqote_backend.rs

@@ -90,6 +90,7 @@ impl<'a> CanvasPaintState<'a> {
             shadow_offset_y: 0.0,
             shadow_blur: 0.0,
             shadow_color: Color::Raqote(raqote::SolidSource::from_unpremultiplied_argb(0, 0, 0, 0)),
+            font_style: None,
         }
     }
 }

components/canvas_traits/Cargo.toml

@@ -27,6 +27,7 @@ serde = "1.0"
 serde_bytes = "0.11"
 servo_config = { path = "../config" }
 sparkle = "0.1"
+style = { path = "../style" }
 time = { version = "0.1.0", optional = true }
 webrender_api = { git = "https://github.com/servo/webrender" }
 webxr-api = { git = "https://github.com/servo/webxr", features = ["ipc"] }

components/canvas_traits/canvas.rs

@@ -8,6 +8,7 @@ use ipc_channel::ipc::{IpcBytesReceiver, IpcBytesSender, IpcSender, IpcSharedMem
 use serde_bytes::ByteBuf;
 use std::default::Default;
 use std::str::FromStr;
+use style::properties::style_structs::Font;
 
 #[derive(Clone, Debug, Deserialize, Serialize)]
 pub enum FillRule {
@@ -70,6 +71,7 @@ pub enum Canvas2dMsg {
     SetShadowOffsetY(f64),
     SetShadowBlur(f64),
     SetShadowColor(RGBA),
+    SetFont(Font),
 }
 
 #[derive(Clone, Debug, Deserialize, Serialize)]

components/script/canvas_state.rs

@@ -49,7 +49,10 @@ use std::cell::Cell;
 use std::fmt;
 use std::str::FromStr;
 use std::sync::Arc;
+use style::properties::longhands::font_variant_caps::computed_value::T as FontVariantCaps;
 use style::properties::style_structs::Font;
+use style::values::computed::font::FontStyle;
+use style_traits::values::ToCss;
 
 #[unrooted_must_root_lint::must_root]
 #[derive(Clone, JSTraceable, MallocSizeOf)]
@@ -1026,16 +1029,24 @@ impl CanvasState {
         };
         let node = canvas.upcast::<Node>();
         let window = window_from_node(&*canvas);
-        let font_style = match window.resolved_font_style_query(&node, value.to_string()) {
+        let resolved_font_style = match window.resolved_font_style_query(&node, value.to_string()) {
             Some(value) => value,
             None => return, // syntax error
         };
-        self.state.borrow_mut().font_style = Some((*font_style).clone());
+        self.state.borrow_mut().font_style = Some((*resolved_font_style).clone());
+        self.send_canvas_2d_msg(Canvas2dMsg::SetFont((*resolved_font_style).clone()));
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-context-2d-font
     pub fn font(&self) -> DOMString {
-        unimplemented!()
+        self.state.borrow().font_style.as_ref().map_or_else(
+            || DOMString::from("10px sans-serif"),
+            |style| {
+                let mut result = String::new();
+                serialize_font(style, &mut result).unwrap();
+                DOMString::from(result)
+            },
+        )
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-context-2d-linewidth
@@ -1663,3 +1674,24 @@ pub fn adjust_size_sign(
     }
     (origin, size.to_u32())
 }
+
+fn serialize_font<W>(style: &Font, dest: &mut W) -> fmt::Result
+where
+    W: fmt::Write,
+{
+    if style.font_style == FontStyle::Italic {
+        write!(dest, "{} ", style.font_style.to_css_string())?;
+    }
+    if style.font_weight.is_bold() {
+        write!(dest, "{} ", style.font_weight.to_css_string())?;
+    }
+    if style.font_variant_caps == FontVariantCaps::SmallCaps {
+        write!(dest, "{} ", style.font_variant_caps.to_css_string())?;
+    }
+    write!(
+        dest,
+        "{} {}",
+        style.font_size.to_css_string(),
+        style.font_family.to_css_string()
+    )
+}

components/style/properties/properties.mako.rs

@@ -2601,7 +2601,7 @@ pub mod style_structs {
 
     % for style_struct in data.active_style_structs():
         % if style_struct.name == "Font":
-        #[derive(Clone, Debug, MallocSizeOf)]
+        #[derive(Clone, Debug, MallocSizeOf, Serialize, Deserialize)]
         % else:
         #[derive(Clone, Debug, MallocSizeOf, PartialEq)]
         % endif

components/style/values/computed/font.rs

@@ -80,6 +80,8 @@ impl ToAnimatedValue for FontWeight {
     ToAnimatedZero,
     ToCss,
     ToResolvedValue,
+    Serialize,
+    Deserialize,
 )]
 /// The computed value of font-size
 pub struct FontSize {
@@ -179,7 +181,7 @@ impl ToAnimatedValue for FontSize {
 }
 
 #[derive(Clone, Debug, Eq, PartialEq, ToComputedValue, ToResolvedValue)]
-#[cfg_attr(feature = "servo", derive(Hash, MallocSizeOf))]
+#[cfg_attr(feature = "servo", derive(Hash, MallocSizeOf, Serialize, Deserialize))]
 /// Specifies a prioritized list of font family names or generic family names.
 pub struct FontFamily {
     /// The actual list of family names.
@@ -445,7 +447,17 @@ impl SingleFontFamily {
 
 #[cfg(feature = "servo")]
 #[derive(
-    Clone, Debug, Eq, Hash, MallocSizeOf, PartialEq, ToComputedValue, ToResolvedValue, ToShmem,
+    Clone,
+    Debug,
+    Eq,
+    Hash,
+    MallocSizeOf,
+    PartialEq,
+    ToComputedValue,
+    ToResolvedValue,
+    ToShmem,
+    Serialize,
+    Deserialize,
 )]
 /// A list of SingleFontFamily
 pub struct FontFamilyList(Box<[SingleFontFamily]>);

components/style/values/specified/font.rs

@@ -496,6 +496,8 @@ impl ToComputedValue for FontStretch {
     ToCss,
     ToResolvedValue,
     ToShmem,
+    Serialize,
+    Deserialize,
 )]
 #[allow(missing_docs)]
 pub enum KeywordSize {
@@ -540,6 +542,8 @@ impl Default for KeywordSize {
     ToCss,
     ToResolvedValue,
     ToShmem,
+    Serialize,
+    Deserialize,
 )]
 /// Additional information for keyword-derived font sizes.
 pub struct KeywordInfo {