Enable new color functions from CSS Color 4 (#30752)

I will need to do most of the work anyways during the style updates,
so by enabling this it will be easier to detect mistakes.

Also, canvas colors are now parsed as <color>, precisely to support
these new features. This is according to the HTML spec:
https://html.spec.whatwg.org/multipage/infrastructure.html#parsed-as-a-css-color-value

1 files changed, 43 insertions, 33 deletions

diff --git a/components/script/canvas_state.rs b/components/script/canvas_state.rs
index 9f03847de37..06e80f2bb05 100644
--- a/components/script/canvas_state.rs
+++ b/components/script/canvas_state.rs
@@ -12,7 +12,7 @@ use canvas_traits::canvas::{
     FillRule, LineCapStyle, LineJoinStyle, LinearGradientStyle, RadialGradientStyle,
     RepetitionStyle, TextAlign, TextBaseline,
 };
-use cssparser::{Color as CSSColor, Parser, ParserInput, RGBA};
+use cssparser::{Parser, ParserInput, RGBA};
 use euclid::default::{Point2D, Rect, Size2D, Transform2D};
 use euclid::vec2;
 use ipc_channel::ipc::{self, IpcSender, IpcSharedMemory};
@@ -22,10 +22,15 @@ use pixels::PixelFormat;
 use profile_traits::ipc as profiled_ipc;
 use script_traits::ScriptMsg;
 use servo_url::{ImmutableOrigin, ServoUrl};
+use style::context::QuirksMode;
+use style::parser::ParserContext;
 use style::properties::longhands::font_variant_caps::computed_value::T as FontVariantCaps;
 use style::properties::style_structs::Font;
+use style::stylesheets::{CssRuleType, Origin};
 use style::values::computed::font::FontStyle;
+use style::values::specified::color::Color;
 use style_traits::values::ToCss;
+use style_traits::ParsingMode;
 
 use crate::dom::bindings::cell::DomRefCell;
 use crate::dom::bindings::codegen::Bindings::CanvasRenderingContext2DBinding::{
@@ -1665,40 +1670,45 @@ impl CanvasState {
     }
 }
 
-fn parse_color(canvas: Option<&HTMLCanvasElement>, string: &str) -> Result<RGBA, ()> {
+pub fn parse_color(canvas: Option<&HTMLCanvasElement>, string: &str) -> Result<RGBA, ()> {
     let mut input = ParserInput::new(string);
     let mut parser = Parser::new(&mut input);
-    let color = CSSColor::parse(&mut parser);
-    if parser.is_exhausted() {
-        match color {
-            Ok(CSSColor::Rgba(rgba)) => Ok(rgba),
-            Ok(CSSColor::CurrentColor) => {
-                // TODO: https://github.com/whatwg/html/issues/1099
-                // Reconsider how to calculate currentColor in a display:none canvas
-
-                // TODO: will need to check that the context bitmap mode is fixed
-                // once we implement CanvasProxy
-                let canvas = match canvas {
-                    // https://drafts.css-houdini.org/css-paint-api/#2d-rendering-context
-                    // Whenever "currentColor" is used as a color in the PaintRenderingContext2D API,
-                    // it is treated as opaque black.
-                    None => return Ok(RGBA::new(0, 0, 0, 1.0)),
-                    Some(ref canvas) => &**canvas,
-                };
-
-                let canvas_element = canvas.upcast::<Element>();
-
-                match canvas_element.style() {
-                    Some(ref s) if canvas_element.has_css_layout_box() => {
-                        Ok(s.get_inherited_text().color)
-                    },
-                    _ => Ok(RGBA::new(0, 0, 0, 1.0)),
-                }
-            },
-            _ => Err(()),
-        }
-    } else {
-        Err(())
+    let url = ServoUrl::parse("about:blank").unwrap();
+    let context = ParserContext::new(
+        Origin::Author,
+        &url,
+        Some(CssRuleType::Style),
+        ParsingMode::DEFAULT,
+        QuirksMode::NoQuirks,
+        None,
+        None,
+    );
+    match Color::parse_and_compute(&context, &mut parser, None) {
+        Some(color) => {
+            // TODO: https://github.com/whatwg/html/issues/1099
+            // Reconsider how to calculate currentColor in a display:none canvas
+
+            // TODO: will need to check that the context bitmap mode is fixed
+            // once we implement CanvasProxy
+            let current_color = match canvas {
+                // https://drafts.css-houdini.org/css-paint-api/#2d-rendering-context
+                // Whenever "currentColor" is used as a color in the PaintRenderingContext2D API,
+                // it is treated as opaque black.
+                None => RGBA::new(0, 0, 0, 1.0),
+                Some(ref canvas) => {
+                    let canvas_element = canvas.upcast::<Element>();
+                    match canvas_element.style() {
+                        Some(ref s) if canvas_element.has_css_layout_box() => {
+                            s.get_inherited_text().color
+                        },
+                        _ => RGBA::new(0, 0, 0, 1.0),
+                    }
+                },
+            };
+
+            Ok(color.into_rgba(current_color))
+        },
+        None => Err(()),
     }
 }