servo/components/script/dom/canvasgradient.rs

/* This Source Code Form is subject to the terms of the Mozilla Public
 * 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 cssparser::RGBA;
use canvas_traits::{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::Root;
use dom::bindings::num::Finite;
use dom::bindings::utils::{Reflector, reflect_dom_object};
use dom::canvasrenderingcontext2d::parse_color;

// https://html.spec.whatwg.org/multipage/#canvasgradient
#[dom_struct]
pub struct CanvasGradient {
    reflector_: Reflector,
    style: CanvasGradientStyle,
    stops: DOMRefCell<Vec<CanvasGradientStop>>,
}

#[derive(JSTraceable, Clone)]
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) -> Root<CanvasGradient> {
        reflect_dom_object(box CanvasGradient::new_inherited(style),
                           global, CanvasGradientBinding::Wrap)
    }
}

impl<'a> CanvasGradientMethods for &'a CanvasGradient {
    // https://html.spec.whatwg.org/multipage/#dom-canvasgradient-addcolorstop
    fn AddColorStop(self, offset: Finite<f64>, 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).unwrap_or(default_black),
        });
    }
}

pub trait ToFillOrStrokeStyle {
    fn to_fill_or_stroke_style(self) -> FillOrStrokeStyle;
}

impl<'a> ToFillOrStrokeStyle for &'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))
            }
        }
    }
}