servo/components/canvas/canvas_render_task.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 azure::azure_hl::{DrawTarget, Color, B8G8R8A8, SkiaBackend, StrokeOptions, DrawOptions};
use azure::azure_hl::ColorPattern;
use geom::rect::Rect;
use geom::size::Size2D;

use std::comm;
use std::task::TaskBuilder;

pub enum CanvasMsg {
    FillRect(Rect<f32>),
    ClearRect(Rect<f32>),
    StrokeRect(Rect<f32>),
    Recreate(Size2D<i32>),
    Close,
}

pub struct CanvasRenderTask {
    drawtarget: DrawTarget,
    fill_color: ColorPattern,
    stroke_color: ColorPattern,
    stroke_opts: StrokeOptions,
}

impl CanvasRenderTask {
    fn new(size: Size2D<i32>) -> CanvasRenderTask {
        CanvasRenderTask {
            drawtarget: CanvasRenderTask::create(size),
            fill_color: ColorPattern::new(Color::new(0., 0., 0., 1.)),
            stroke_color: ColorPattern::new(Color::new(0., 0., 0., 1.)),
            stroke_opts: StrokeOptions::new(1.0, 1.0),
        }
    }

    pub fn start(size: Size2D<i32>) -> Sender<CanvasMsg> {
        let (chan, port) = comm::channel::<CanvasMsg>();
        let builder = TaskBuilder::new().named("CanvasTask");
        builder.spawn(proc() {
            let mut renderer = CanvasRenderTask::new(size);

            loop {
                match port.recv() {
                    FillRect(ref rect) => renderer.fill_rect(rect),
                    StrokeRect(ref rect) => renderer.stroke_rect(rect),
                    ClearRect(ref rect) => renderer.clear_rect(rect),
                    Recreate(size) => renderer.recreate(size),
                    Close => break,
                }
            }
        });
        chan
    }

    fn fill_rect(&self, rect: &Rect<f32>) {
        let drawopts = DrawOptions::new(1.0, 0);
        self.drawtarget.fill_rect(rect, &self.fill_color, Some(&drawopts));
    }

    fn clear_rect(&self, rect: &Rect<f32>) {
        self.drawtarget.clear_rect(rect);
    }

    fn stroke_rect(&self, rect: &Rect<f32>) {
        let drawopts = DrawOptions::new(1.0, 0);
        self.drawtarget.stroke_rect(rect, &self.stroke_color, &self.stroke_opts, &drawopts);
    }

    fn create(size: Size2D<i32>) -> DrawTarget {
        DrawTarget::new(SkiaBackend, size, B8G8R8A8)
    }

    fn recreate(&mut self, size: Size2D<i32>) {
        self.drawtarget = CanvasRenderTask::create(size);
    }
}