Implement gradient fill styles for canvas.

components/script/dom/canvasgradient.rs

@@ -2,10 +2,80 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use dom::bindings::utils::Reflector;
+use cssparser::RGBA;
+use canvas::canvas_paint_task::{CanvasGradientStop, FillOrStrokeStyle, LinearGradientStyle, RadialGradientStyle};
+use dom::bindings::cell::DOMRefCell;
+use dom::bindings::codegen::Bindings::CanvasGradientBinding;
+use dom::bindings::codegen::Bindings::CanvasGradientBinding::CanvasGradientMethods;
+use dom::bindings::global::GlobalRef;
+use dom::bindings::js::{JSRef, Temporary};
+use dom::bindings::utils::{Reflector, reflect_dom_object};
+use dom::canvasrenderingcontext2d::parse_color;
 
 #[dom_struct]
 pub struct CanvasGradient {
     reflector_: Reflector,
+    style: CanvasGradientStyle,
+    stops: DOMRefCell<Vec<CanvasGradientStop>>,
 }
 
+#[jstraceable]
+pub enum CanvasGradientStyle {
+    Linear(LinearGradientStyle),
+    Radial(RadialGradientStyle),
+}
+
+impl CanvasGradient {
+    fn new_inherited(style: CanvasGradientStyle) -> CanvasGradient {
+        CanvasGradient {
+            reflector_: Reflector::new(),
+            style: style,
+            stops: DOMRefCell::new(Vec::new()),
+        }
+    }
+
+    pub fn new(global: GlobalRef, style: CanvasGradientStyle) -> Temporary<CanvasGradient> {
+        reflect_dom_object(box CanvasGradient::new_inherited(style),
+                           global, CanvasGradientBinding::Wrap)
+    }
+}
+
+impl<'a> CanvasGradientMethods for JSRef<'a, CanvasGradient> {
+    fn AddColorStop(self, offset: f32, color: String) {
+        let default_black = RGBA {
+            red: 0.0,
+            green: 0.0,
+            blue: 0.0,
+            alpha: 1.0,
+        };
+
+        self.stops.borrow_mut().push(CanvasGradientStop {
+            offset: offset as f64,
+            color: parse_color(color.as_slice()).unwrap_or(default_black),
+        });
+    }
+}
+
+pub trait ToFillOrStrokeStyle {
+    fn to_fill_or_stroke_style(&self) -> FillOrStrokeStyle;
+}
+
+impl<'a> ToFillOrStrokeStyle for JSRef<'a, CanvasGradient> {
+    fn to_fill_or_stroke_style(&self) -> FillOrStrokeStyle {
+        let gradient_stops = self.stops.borrow().clone();
+        match self.style {
+            CanvasGradientStyle::Linear(ref gradient) =>  {
+                FillOrStrokeStyle::LinearGradient(
+                    LinearGradientStyle::new(gradient.x0, gradient.y0,
+                                             gradient.x1, gradient.y1,
+                                             gradient_stops))
+            },
+            CanvasGradientStyle::Radial(ref gradient) => {
+                FillOrStrokeStyle::RadialGradient(
+                    RadialGradientStyle::new(gradient.x0, gradient.y0, gradient.r0,
+                                             gradient.x1, gradient.y1, gradient.r1,
+                                             gradient_stops))
+            }
+        }
+    }
+}