servo/components/canvas/raqote_backend.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 https://mozilla.org/MPL/2.0/. */

use std::cell::RefCell;
use std::collections::HashMap;

use canvas_traits::canvas::*;
use cssparser::color::clamp_unit_f32;
use euclid::default::{Point2D, Rect, Size2D, Transform2D, Vector2D};
use euclid::Angle;
use font_kit::font::Font;
use fonts::{ByteIndex, FontIdentifier, FontTemplateRefMethods};
use log::warn;
use lyon_geom::Arc;
use range::Range;
use raqote::PathOp;
use style::color::AbsoluteColor;

use crate::canvas_data::{
    self, Backend, CanvasPaintState, Color, CompositionOp, DrawOptions, Filter, GenericDrawTarget,
    GenericPathBuilder, GradientStop, GradientStops, Path, SourceSurface, StrokeOptions, TextRun,
};
use crate::canvas_paint_thread::AntialiasMode;

thread_local! {
    /// The shared font cache used by all canvases that render on a thread. It would be nicer
    /// to have a global cache, but it looks like font-kit uses a per-thread FreeType, so
    /// in order to ensure that fonts are particular to a thread we have to make our own
    /// cache thread local as well.
    static SHARED_FONT_CACHE: RefCell<HashMap<FontIdentifier, Font>> = RefCell::default();
}

#[derive(Default)]
pub struct RaqoteBackend;

impl Backend for RaqoteBackend {
    fn get_composition_op(&self, opts: &DrawOptions) -> CompositionOp {
        CompositionOp::Raqote(opts.as_raqote().blend_mode)
    }

    fn need_to_draw_shadow(&self, color: &Color) -> bool {
        color.as_raqote().a != 0
    }

    fn set_shadow_color(&mut self, color: AbsoluteColor, state: &mut CanvasPaintState<'_>) {
        state.shadow_color = Color::Raqote(color.to_raqote_style());
    }

    fn set_fill_style(
        &mut self,
        style: FillOrStrokeStyle,
        state: &mut CanvasPaintState<'_>,
        _drawtarget: &dyn GenericDrawTarget,
    ) {
        if let Some(pattern) = style.to_raqote_pattern() {
            state.fill_style = canvas_data::Pattern::Raqote(pattern);
        }
    }

    fn set_stroke_style(
        &mut self,
        style: FillOrStrokeStyle,
        state: &mut CanvasPaintState<'_>,
        _drawtarget: &dyn GenericDrawTarget,
    ) {
        if let Some(pattern) = style.to_raqote_pattern() {
            state.stroke_style = canvas_data::Pattern::Raqote(pattern);
        }
    }

    fn set_global_composition(
        &mut self,
        op: CompositionOrBlending,
        state: &mut CanvasPaintState<'_>,
    ) {
        state.draw_options.as_raqote_mut().blend_mode = op.to_raqote_style();
    }

    fn create_drawtarget(&self, size: Size2D<u64>) -> Box<dyn GenericDrawTarget> {
        Box::new(raqote::DrawTarget::new(
            size.width as i32,
            size.height as i32,
        ))
    }

    fn recreate_paint_state<'a>(&self, _state: &CanvasPaintState<'a>) -> CanvasPaintState<'a> {
        CanvasPaintState::new(AntialiasMode::Default)
    }
}

impl<'a> CanvasPaintState<'a> {
    pub fn new(_antialias: AntialiasMode) -> CanvasPaintState<'a> {
        let pattern = Pattern::Color(255, 0, 0, 0);
        CanvasPaintState {
            draw_options: DrawOptions::Raqote(raqote::DrawOptions::new()),
            fill_style: canvas_data::Pattern::Raqote(pattern.clone()),
            stroke_style: canvas_data::Pattern::Raqote(pattern),
            stroke_opts: StrokeOptions::Raqote(Default::default()),
            transform: Transform2D::identity(),
            shadow_offset_x: 0.0,
            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,
            text_align: TextAlign::default(),
            text_baseline: TextBaseline::default(),
        }
    }
}

#[derive(Clone)]
pub enum Pattern<'a> {
    // argb
    Color(u8, u8, u8, u8),
    LinearGradient(LinearGradientPattern),
    RadialGradient(RadialGradientPattern),
    Surface(SurfacePattern<'a>),
}

impl<'a> Pattern<'a> {
    fn set_transform(&mut self, transform: Transform2D<f32>) {
        match self {
            Pattern::Surface(pattern) => pattern.set_transform(transform),
            Pattern::LinearGradient(..) | Pattern::RadialGradient(..) | Pattern::Color(..) => {
                warn!("transform not supported")
            },
        }
    }
}

#[derive(Clone)]
pub struct LinearGradientPattern {
    gradient: raqote::Gradient,
    start: Point2D<f32>,
    end: Point2D<f32>,
}

impl LinearGradientPattern {
    fn new(start: Point2D<f32>, end: Point2D<f32>, stops: Vec<raqote::GradientStop>) -> Self {
        LinearGradientPattern {
            gradient: raqote::Gradient { stops },
            start,
            end,
        }
    }
}

#[derive(Clone)]
pub struct RadialGradientPattern {
    gradient: raqote::Gradient,
    center1: Point2D<f32>,
    radius1: f32,
    center2: Point2D<f32>,
    radius2: f32,
}

impl RadialGradientPattern {
    fn new(
        center1: Point2D<f32>,
        radius1: f32,
        center2: Point2D<f32>,
        radius2: f32,
        stops: Vec<raqote::GradientStop>,
    ) -> Self {
        RadialGradientPattern {
            gradient: raqote::Gradient { stops },
            center1,
            radius1,
            center2,
            radius2,
        }
    }
}

#[derive(Clone)]
pub struct SurfacePattern<'a> {
    image: raqote::Image<'a>,
    filter: raqote::FilterMode,
    extend: raqote::ExtendMode,
    repeat: Repetition,
    transform: Transform2D<f32>,
}

impl<'a> SurfacePattern<'a> {
    fn new(image: raqote::Image<'a>, filter: raqote::FilterMode, repeat: Repetition) -> Self {
        let extend = match repeat {
            Repetition::NoRepeat => raqote::ExtendMode::Pad,
            Repetition::RepeatX | Repetition::RepeatY | Repetition::Repeat => {
                raqote::ExtendMode::Repeat
            },
        };
        SurfacePattern {
            image,
            filter,
            extend,
            repeat,
            transform: Transform2D::identity(),
        }
    }
    fn set_transform(&mut self, transform: Transform2D<f32>) {
        self.transform = transform;
    }
    pub fn size(&self) -> Size2D<f32> {
        Size2D::new(self.image.width as f32, self.image.height as f32)
    }
    pub fn repetition(&self) -> &Repetition {
        &self.repeat
    }
}

#[derive(Clone)]
pub enum Repetition {
    Repeat,
    RepeatX,
    RepeatY,
    NoRepeat,
}

impl Repetition {
    fn from_xy(repeat_x: bool, repeat_y: bool) -> Self {
        if repeat_x && repeat_y {
            Repetition::Repeat
        } else if repeat_x {
            Repetition::RepeatX
        } else if repeat_y {
            Repetition::RepeatY
        } else {
            Repetition::NoRepeat
        }
    }
}

impl canvas_data::Pattern<'_> {
    pub fn source(&self) -> raqote::Source {
        match self {
            canvas_data::Pattern::Raqote(pattern) => match pattern {
                Pattern::Color(a, r, g, b) => raqote::Source::Solid(
                    raqote::SolidSource::from_unpremultiplied_argb(*a, *r, *g, *b),
                ),
                Pattern::LinearGradient(pattern) => raqote::Source::new_linear_gradient(
                    pattern.gradient.clone(),
                    pattern.start,
                    pattern.end,
                    raqote::Spread::Pad,
                ),
                Pattern::RadialGradient(pattern) => raqote::Source::new_two_circle_radial_gradient(
                    pattern.gradient.clone(),
                    pattern.center1,
                    pattern.radius1,
                    pattern.center2,
                    pattern.radius2,
                    raqote::Spread::Pad,
                ),
                Pattern::Surface(pattern) => raqote::Source::Image(
                    pattern.image,
                    pattern.extend,
                    pattern.filter,
                    pattern.transform,
                ),
            },
        }
    }
    pub fn is_zero_size_gradient(&self) -> bool {
        match self {
            canvas_data::Pattern::Raqote(pattern) => match pattern {
                Pattern::RadialGradient(pattern) => {
                    let centers_equal = pattern.center1 == pattern.center2;
                    let radii_equal = pattern.radius1 == pattern.radius2;
                    (centers_equal && radii_equal) || pattern.gradient.stops.is_empty()
                },
                Pattern::LinearGradient(pattern) => {
                    (pattern.start == pattern.end) || pattern.gradient.stops.is_empty()
                },
                Pattern::Color(..) | Pattern::Surface(..) => false,
            },
        }
    }
}

impl StrokeOptions {
    pub fn set_line_width(&mut self, _val: f32) {
        match self {
            StrokeOptions::Raqote(options) => options.width = _val,
        }
    }
    pub fn set_miter_limit(&mut self, _val: f32) {
        match self {
            StrokeOptions::Raqote(options) => options.miter_limit = _val,
        }
    }
    pub fn set_line_join(&mut self, val: LineJoinStyle) {
        match self {
            StrokeOptions::Raqote(options) => options.join = val.to_raqote_style(),
        }
    }
    pub fn set_line_cap(&mut self, val: LineCapStyle) {
        match self {
            StrokeOptions::Raqote(options) => options.cap = val.to_raqote_style(),
        }
    }
    pub fn as_raqote(&self) -> &raqote::StrokeStyle {
        match self {
            StrokeOptions::Raqote(options) => options,
        }
    }
}

impl DrawOptions {
    pub fn set_alpha(&mut self, val: f32) {
        match self {
            DrawOptions::Raqote(draw_options) => draw_options.alpha = val,
        }
    }
    pub fn as_raqote(&self) -> &raqote::DrawOptions {
        match self {
            DrawOptions::Raqote(options) => options,
        }
    }
    fn as_raqote_mut(&mut self) -> &mut raqote::DrawOptions {
        match self {
            DrawOptions::Raqote(options) => options,
        }
    }
}

impl Path {
    pub fn transformed_copy_to_builder(
        &self,
        transform: &Transform2D<f32>,
    ) -> Box<dyn GenericPathBuilder> {
        Box::new(PathBuilder(Some(raqote::PathBuilder::from(
            self.as_raqote().clone().transform(transform),
        ))))
    }

    pub fn contains_point(&self, x: f64, y: f64, path_transform: &Transform2D<f32>) -> bool {
        self.as_raqote()
            .clone()
            .transform(path_transform)
            .contains_point(0.1, x as f32, y as f32)
    }

    pub fn copy_to_builder(&self) -> Box<dyn GenericPathBuilder> {
        Box::new(PathBuilder(Some(raqote::PathBuilder::from(
            self.as_raqote().clone(),
        ))))
    }

    pub fn as_raqote(&self) -> &raqote::Path {
        match self {
            Path::Raqote(p) => p,
        }
    }
}

fn create_gradient_stops(gradient_stops: Vec<CanvasGradientStop>) -> Vec<raqote::GradientStop> {
    let mut stops = gradient_stops
        .into_iter()
        .map(|item| item.to_raqote())
        .collect::<Vec<raqote::GradientStop>>();
    // https://www.w3.org/html/test/results/2dcontext/annotated-spec/canvas.html#testrefs.2d.gradient.interpolate.overlap
    stops.sort_by(|a, b| a.position.partial_cmp(&b.position).unwrap());
    stops
}

impl GenericDrawTarget for raqote::DrawTarget {
    fn clear_rect(&mut self, rect: &Rect<f32>) {
        let mut pb = raqote::PathBuilder::new();
        pb.rect(
            rect.origin.x,
            rect.origin.y,
            rect.size.width,
            rect.size.height,
        );
        let mut options = raqote::DrawOptions::new();
        options.blend_mode = raqote::BlendMode::Clear;
        let pattern = Pattern::Color(0, 0, 0, 0);
        GenericDrawTarget::fill(
            self,
            &Path::Raqote(pb.finish()),
            canvas_data::Pattern::Raqote(pattern),
            &DrawOptions::Raqote(options),
        );
    }
    #[allow(unsafe_code)]
    fn copy_surface(
        &mut self,
        surface: SourceSurface,
        source: Rect<i32>,
        destination: Point2D<i32>,
    ) {
        let mut dt = raqote::DrawTarget::new(source.size.width, source.size.height);
        let data = surface.as_raqote();
        let s = unsafe { std::slice::from_raw_parts(data.as_ptr() as *const u32, data.len() / 4) };
        dt.get_data_mut().copy_from_slice(s);
        raqote::DrawTarget::copy_surface(self, &dt, source.to_box2d(), destination);
    }
    // TODO(pylbrecht)
    // Somehow a duplicate of `create_gradient_stops()` with different types.
    // It feels cumbersome to convert GradientStop back and forth just to use
    // `create_gradient_stops()`, so I'll leave this here for now.
    fn create_gradient_stops(&self, gradient_stops: Vec<GradientStop>) -> GradientStops {
        let mut stops = gradient_stops
            .into_iter()
            .map(|item| *item.as_raqote())
            .collect::<Vec<raqote::GradientStop>>();
        // https://www.w3.org/html/test/results/2dcontext/annotated-spec/canvas.html#testrefs.2d.gradient.interpolate.overlap
        stops.sort_by(|a, b| a.position.partial_cmp(&b.position).unwrap());
        GradientStops::Raqote(stops)
    }

    fn create_path_builder(&self) -> Box<dyn GenericPathBuilder> {
        Box::new(PathBuilder::new())
    }
    fn create_similar_draw_target(&self, size: &Size2D<i32>) -> Box<dyn GenericDrawTarget> {
        Box::new(raqote::DrawTarget::new(size.width, size.height))
    }
    fn create_source_surface_from_data(&self, data: &[u8]) -> Option<SourceSurface> {
        Some(SourceSurface::Raqote(data.to_vec()))
    }
    #[allow(unsafe_code)]
    fn draw_surface(
        &mut self,
        surface: SourceSurface,
        dest: Rect<f64>,
        source: Rect<f64>,
        filter: Filter,
        draw_options: &DrawOptions,
    ) {
        let surface_data = surface.as_raqote();
        let image = raqote::Image {
            width: source.size.width as i32,
            height: source.size.height as i32,
            data: unsafe {
                std::slice::from_raw_parts(
                    surface_data.as_ptr() as *const u32,
                    surface_data.len() / std::mem::size_of::<u32>(),
                )
            },
        };

        let mut pattern = Pattern::Surface(SurfacePattern::new(
            image,
            filter.to_raqote(),
            Repetition::NoRepeat,
        ));
        let transform =
            raqote::Transform::translation(-dest.origin.x as f32, -dest.origin.y as f32)
                .then_scale(
                    image.width as f32 / dest.size.width as f32,
                    image.height as f32 / dest.size.height as f32,
                );
        pattern.set_transform(transform);

        let mut pb = raqote::PathBuilder::new();
        pb.rect(
            dest.origin.x as f32,
            dest.origin.y as f32,
            dest.size.width as f32,
            dest.size.height as f32,
        );

        GenericDrawTarget::fill(
            self,
            &Path::Raqote(pb.finish()),
            canvas_data::Pattern::Raqote(pattern),
            draw_options,
        );
    }
    fn draw_surface_with_shadow(
        &self,
        _surface: SourceSurface,
        _dest: &Point2D<f32>,
        _color: &Color,
        _offset: &Vector2D<f32>,
        _sigma: f32,
        _operator: CompositionOp,
    ) {
        warn!("no support for drawing shadows");
    }
    fn fill(&mut self, path: &Path, pattern: canvas_data::Pattern, draw_options: &DrawOptions) {
        match draw_options.as_raqote().blend_mode {
            raqote::BlendMode::Src => {
                self.clear(raqote::SolidSource::from_unpremultiplied_argb(0, 0, 0, 0));
                self.fill(
                    path.as_raqote(),
                    &pattern.source(),
                    draw_options.as_raqote(),
                );
            },
            raqote::BlendMode::Clear |
            raqote::BlendMode::SrcAtop |
            raqote::BlendMode::DstOut |
            raqote::BlendMode::Add |
            raqote::BlendMode::Xor |
            raqote::BlendMode::DstOver |
            raqote::BlendMode::SrcOver => {
                self.fill(
                    path.as_raqote(),
                    &pattern.source(),
                    draw_options.as_raqote(),
                );
            },
            raqote::BlendMode::SrcIn |
            raqote::BlendMode::SrcOut |
            raqote::BlendMode::DstIn |
            raqote::BlendMode::DstAtop => {
                let mut options = *draw_options.as_raqote();
                self.push_layer_with_blend(1., options.blend_mode);
                options.blend_mode = raqote::BlendMode::SrcOver;
                self.fill(path.as_raqote(), &pattern.source(), &options);
                self.pop_layer();
            },
            _ => warn!(
                "unrecognized blend mode: {:?}",
                draw_options.as_raqote().blend_mode
            ),
        }
    }

    fn fill_text(
        &mut self,
        text_runs: Vec<TextRun>,
        start: Point2D<f32>,
        pattern: &canvas_data::Pattern,
        draw_options: &DrawOptions,
    ) {
        let mut advance = 0.;
        for run in text_runs.iter() {
            let mut positions = Vec::new();
            let glyphs = &run.glyphs;
            let ids: Vec<_> = glyphs
                .iter_glyphs_for_byte_range(&Range::new(ByteIndex(0), glyphs.len()))
                .map(|glyph| {
                    let glyph_offset = glyph.offset().unwrap_or(Point2D::zero());
                    positions.push(Point2D::new(
                        advance + start.x + glyph_offset.x.to_f32_px(),
                        start.y + glyph_offset.y.to_f32_px(),
                    ));
                    advance += glyph.advance().to_f32_px();
                    glyph.id()
                })
                .collect();

            // TODO: raqote uses font-kit to rasterize glyphs, but font-kit fails an assertion when
            // using color bitmap fonts in the FreeType backend. For now, simply do not render these
            // type of fonts.
            if run.font.has_color_bitmap_or_colr_table() {
                continue;
            }

            let template = &run.font.template;

            SHARED_FONT_CACHE.with(|font_cache| {
                let identifier = template.identifier();
                if !font_cache.borrow().contains_key(&identifier) {
                    let Ok(font) =
                        Font::from_bytes(run.font.data.as_arc().clone(), identifier.index())
                    else {
                        return;
                    };
                    font_cache.borrow_mut().insert(identifier.clone(), font);
                }

                let font_cache = font_cache.borrow();
                let Some(font) = font_cache.get(&identifier) else {
                    return;
                };

                self.draw_glyphs(
                    font,
                    run.font.descriptor.pt_size.to_f32_px(),
                    &ids,
                    &positions,
                    &pattern.source(),
                    draw_options.as_raqote(),
                );
            })
        }
    }

    fn fill_rect(
        &mut self,
        rect: &Rect<f32>,
        pattern: canvas_data::Pattern,
        draw_options: Option<&DrawOptions>,
    ) {
        let mut pb = raqote::PathBuilder::new();
        pb.rect(
            rect.origin.x,
            rect.origin.y,
            rect.size.width,
            rect.size.height,
        );
        let draw_options = if let Some(options) = draw_options {
            *options.as_raqote()
        } else {
            raqote::DrawOptions::new()
        };

        GenericDrawTarget::fill(
            self,
            &Path::Raqote(pb.finish()),
            pattern,
            &DrawOptions::Raqote(draw_options),
        );
    }
    fn get_size(&self) -> Size2D<i32> {
        Size2D::new(self.width(), self.height())
    }
    fn get_transform(&self) -> Transform2D<f32> {
        *self.get_transform()
    }
    fn pop_clip(&mut self) {
        self.pop_clip();
    }
    fn push_clip(&mut self, path: &Path) {
        self.push_clip(path.as_raqote());
    }
    fn set_transform(&mut self, matrix: &Transform2D<f32>) {
        self.set_transform(matrix);
    }
    fn snapshot(&self) -> SourceSurface {
        SourceSurface::Raqote(self.snapshot_data_owned())
    }
    fn stroke(
        &mut self,
        path: &Path,
        pattern: canvas_data::Pattern,
        stroke_options: &StrokeOptions,
        draw_options: &DrawOptions,
    ) {
        self.stroke(
            path.as_raqote(),
            &pattern.source(),
            stroke_options.as_raqote(),
            draw_options.as_raqote(),
        );
    }
    fn stroke_line(
        &mut self,
        start: Point2D<f32>,
        end: Point2D<f32>,
        pattern: canvas_data::Pattern,
        stroke_options: &StrokeOptions,
        draw_options: &DrawOptions,
    ) {
        let mut pb = raqote::PathBuilder::new();
        pb.move_to(start.x, start.y);
        pb.line_to(end.x, end.y);
        let mut stroke_options = stroke_options.as_raqote().clone();
        let cap = match stroke_options.join {
            raqote::LineJoin::Round => raqote::LineCap::Round,
            _ => raqote::LineCap::Butt,
        };
        stroke_options.cap = cap;

        self.stroke(
            &pb.finish(),
            &pattern.source(),
            &stroke_options,
            draw_options.as_raqote(),
        );
    }
    fn stroke_rect(
        &mut self,
        rect: &Rect<f32>,
        pattern: canvas_data::Pattern,
        stroke_options: &StrokeOptions,
        draw_options: &DrawOptions,
    ) {
        let mut pb = raqote::PathBuilder::new();
        pb.rect(
            rect.origin.x,
            rect.origin.y,
            rect.size.width,
            rect.size.height,
        );

        self.stroke(
            &pb.finish(),
            &pattern.source(),
            stroke_options.as_raqote(),
            draw_options.as_raqote(),
        );
    }
    #[allow(unsafe_code)]
    fn snapshot_data(&self, f: &dyn Fn(&[u8]) -> Vec<u8>) -> Vec<u8> {
        let v = self.get_data();
        f(
            unsafe {
                std::slice::from_raw_parts(v.as_ptr() as *const u8, std::mem::size_of_val(v))
            },
        )
    }
    #[allow(unsafe_code)]
    fn snapshot_data_owned(&self) -> Vec<u8> {
        let v = self.get_data();
        unsafe {
            std::slice::from_raw_parts(v.as_ptr() as *const u8, std::mem::size_of_val(v)).into()
        }
    }
}

impl Filter {
    fn to_raqote(self) -> raqote::FilterMode {
        match self {
            Filter::Bilinear => raqote::FilterMode::Bilinear,
            Filter::Nearest => raqote::FilterMode::Nearest,
        }
    }
}

struct PathBuilder(Option<raqote::PathBuilder>);

impl PathBuilder {
    fn new() -> PathBuilder {
        PathBuilder(Some(raqote::PathBuilder::new()))
    }
}

impl GenericPathBuilder for PathBuilder {
    fn arc(
        &mut self,
        origin: Point2D<f32>,
        radius: f32,
        start_angle: f32,
        end_angle: f32,
        anticlockwise: bool,
    ) {
        self.ellipse(
            origin,
            radius,
            radius,
            0.,
            start_angle,
            end_angle,
            anticlockwise,
        );
    }
    fn bezier_curve_to(
        &mut self,
        control_point1: &Point2D<f32>,
        control_point2: &Point2D<f32>,
        control_point3: &Point2D<f32>,
    ) {
        self.0.as_mut().unwrap().cubic_to(
            control_point1.x,
            control_point1.y,
            control_point2.x,
            control_point2.y,
            control_point3.x,
            control_point3.y,
        );
    }
    fn close(&mut self) {
        self.0.as_mut().unwrap().close();
    }
    fn ellipse(
        &mut self,
        origin: Point2D<f32>,
        radius_x: f32,
        radius_y: f32,
        rotation_angle: f32,
        start_angle: f32,
        end_angle: f32,
        anticlockwise: bool,
    ) {
        let mut start = Angle::radians(start_angle);
        let mut end = Angle::radians(end_angle);

        // Wrap angles mod 2 * PI if necessary
        if !anticlockwise && start > end + Angle::two_pi() ||
            anticlockwise && end > start + Angle::two_pi()
        {
            start = start.positive();
            end = end.positive();
        }

        // Calculate the total arc we're going to sweep.
        let sweep = match anticlockwise {
            true => {
                if end - start == Angle::two_pi() {
                    -Angle::two_pi()
                } else if end > start {
                    -(Angle::two_pi() - (end - start))
                } else {
                    -(start - end)
                }
            },
            false => {
                if start - end == Angle::two_pi() {
                    Angle::two_pi()
                } else if start > end {
                    Angle::two_pi() - (start - end)
                } else {
                    end - start
                }
            },
        };

        let arc: Arc<f32> = Arc {
            center: origin,
            radii: Vector2D::new(radius_x, radius_y),
            start_angle: start,
            sweep_angle: sweep,
            x_rotation: Angle::radians(rotation_angle),
        };

        self.line_to(arc.from());

        arc.for_each_quadratic_bezier(&mut |q| {
            self.quadratic_curve_to(&q.ctrl, &q.to);
        });
    }

    fn get_current_point(&mut self) -> Option<Point2D<f32>> {
        let path = self.finish();
        self.0 = Some(path.as_raqote().clone().into());

        path.as_raqote().ops.iter().last().and_then(|op| match op {
            PathOp::MoveTo(point) | PathOp::LineTo(point) => Some(Point2D::new(point.x, point.y)),
            PathOp::CubicTo(_, _, point) => Some(Point2D::new(point.x, point.y)),
            PathOp::QuadTo(_, point) => Some(Point2D::new(point.x, point.y)),
            PathOp::Close => None,
        })
    }

    fn line_to(&mut self, point: Point2D<f32>) {
        self.0.as_mut().unwrap().line_to(point.x, point.y);
    }
    fn move_to(&mut self, point: Point2D<f32>) {
        self.0.as_mut().unwrap().move_to(point.x, point.y);
    }
    fn quadratic_curve_to(&mut self, control_point: &Point2D<f32>, end_point: &Point2D<f32>) {
        self.0.as_mut().unwrap().quad_to(
            control_point.x,
            control_point.y,
            end_point.x,
            end_point.y,
        );
    }
    fn finish(&mut self) -> Path {
        Path::Raqote(self.0.take().unwrap().finish())
    }
}

pub trait ToRaqoteStyle {
    type Target;

    fn to_raqote_style(self) -> Self::Target;
}

impl ToRaqoteStyle for LineJoinStyle {
    type Target = raqote::LineJoin;

    fn to_raqote_style(self) -> raqote::LineJoin {
        match self {
            LineJoinStyle::Round => raqote::LineJoin::Round,
            LineJoinStyle::Bevel => raqote::LineJoin::Bevel,
            LineJoinStyle::Miter => raqote::LineJoin::Miter,
        }
    }
}

impl ToRaqoteStyle for LineCapStyle {
    type Target = raqote::LineCap;

    fn to_raqote_style(self) -> raqote::LineCap {
        match self {
            LineCapStyle::Butt => raqote::LineCap::Butt,
            LineCapStyle::Round => raqote::LineCap::Round,
            LineCapStyle::Square => raqote::LineCap::Square,
        }
    }
}

pub trait ToRaqotePattern<'a> {
    fn to_raqote_pattern(self) -> Option<Pattern<'a>>;
}

pub trait ToRaqoteGradientStop {
    fn to_raqote(self) -> raqote::GradientStop;
}

impl ToRaqoteGradientStop for CanvasGradientStop {
    fn to_raqote(self) -> raqote::GradientStop {
        let srgb = self.color.into_srgb_legacy();
        let color = raqote::Color::new(
            clamp_unit_f32(srgb.alpha),
            clamp_unit_f32(srgb.components.0),
            clamp_unit_f32(srgb.components.1),
            clamp_unit_f32(srgb.components.2),
        );
        let position = self.offset as f32;
        raqote::GradientStop { position, color }
    }
}

impl ToRaqotePattern<'_> for FillOrStrokeStyle {
    #[allow(unsafe_code)]
    fn to_raqote_pattern(self) -> Option<Pattern<'static>> {
        use canvas_traits::canvas::FillOrStrokeStyle::*;

        match self {
            Color(color) => {
                let srgb = color.into_srgb_legacy();
                Some(Pattern::Color(
                    clamp_unit_f32(srgb.alpha),
                    clamp_unit_f32(srgb.components.0),
                    clamp_unit_f32(srgb.components.1),
                    clamp_unit_f32(srgb.components.2),
                ))
            },
            LinearGradient(style) => {
                let start = Point2D::new(style.x0 as f32, style.y0 as f32);
                let end = Point2D::new(style.x1 as f32, style.y1 as f32);
                let stops = create_gradient_stops(style.stops);
                Some(Pattern::LinearGradient(LinearGradientPattern::new(
                    start, end, stops,
                )))
            },
            RadialGradient(style) => {
                let center1 = Point2D::new(style.x0 as f32, style.y0 as f32);
                let center2 = Point2D::new(style.x1 as f32, style.y1 as f32);
                let stops = create_gradient_stops(style.stops);
                Some(Pattern::RadialGradient(RadialGradientPattern::new(
                    center1,
                    style.r0 as f32,
                    center2,
                    style.r1 as f32,
                    stops,
                )))
            },
            Surface(ref style) => {
                let repeat = Repetition::from_xy(style.repeat_x, style.repeat_y);
                let data = &style.surface_data[..];

                let image = raqote::Image {
                    width: style.surface_size.width as i32,
                    height: style.surface_size.height as i32,
                    data: unsafe {
                        std::slice::from_raw_parts(data.as_ptr() as *const u32, data.len() / 4)
                    },
                };
                Some(Pattern::Surface(SurfacePattern::new(
                    image,
                    raqote::FilterMode::Nearest,
                    repeat,
                )))
            },
        }
    }
}

impl Color {
    fn as_raqote(&self) -> &raqote::SolidSource {
        match self {
            Color::Raqote(s) => s,
        }
    }
}

impl ToRaqoteStyle for AbsoluteColor {
    type Target = raqote::SolidSource;

    fn to_raqote_style(self) -> Self::Target {
        let srgb = self.into_srgb_legacy();
        raqote::SolidSource::from_unpremultiplied_argb(
            clamp_unit_f32(srgb.alpha),
            clamp_unit_f32(srgb.components.0),
            clamp_unit_f32(srgb.components.1),
            clamp_unit_f32(srgb.components.2),
        )
    }
}

impl ToRaqoteStyle for CompositionOrBlending {
    type Target = raqote::BlendMode;

    fn to_raqote_style(self) -> Self::Target {
        match self {
            CompositionOrBlending::Composition(op) => op.to_raqote_style(),
            CompositionOrBlending::Blending(op) => op.to_raqote_style(),
        }
    }
}

impl ToRaqoteStyle for BlendingStyle {
    type Target = raqote::BlendMode;

    fn to_raqote_style(self) -> Self::Target {
        match self {
            BlendingStyle::Multiply => raqote::BlendMode::Multiply,
            BlendingStyle::Screen => raqote::BlendMode::Screen,
            BlendingStyle::Overlay => raqote::BlendMode::Overlay,
            BlendingStyle::Darken => raqote::BlendMode::Darken,
            BlendingStyle::Lighten => raqote::BlendMode::Lighten,
            BlendingStyle::ColorDodge => raqote::BlendMode::ColorDodge,
            BlendingStyle::HardLight => raqote::BlendMode::HardLight,
            BlendingStyle::SoftLight => raqote::BlendMode::SoftLight,
            BlendingStyle::Difference => raqote::BlendMode::Difference,
            BlendingStyle::Exclusion => raqote::BlendMode::Exclusion,
            BlendingStyle::Hue => raqote::BlendMode::Hue,
            BlendingStyle::Saturation => raqote::BlendMode::Saturation,
            BlendingStyle::Color => raqote::BlendMode::Color,
            BlendingStyle::Luminosity => raqote::BlendMode::Luminosity,
            BlendingStyle::ColorBurn => raqote::BlendMode::ColorBurn,
        }
    }
}

impl ToRaqoteStyle for CompositionStyle {
    type Target = raqote::BlendMode;

    fn to_raqote_style(self) -> Self::Target {
        match self {
            CompositionStyle::SrcIn => raqote::BlendMode::SrcIn,
            CompositionStyle::SrcOut => raqote::BlendMode::SrcOut,
            CompositionStyle::SrcOver => raqote::BlendMode::SrcOver,
            CompositionStyle::SrcAtop => raqote::BlendMode::SrcAtop,
            CompositionStyle::DestIn => raqote::BlendMode::DstIn,
            CompositionStyle::DestOut => raqote::BlendMode::DstOut,
            CompositionStyle::DestOver => raqote::BlendMode::DstOver,
            CompositionStyle::DestAtop => raqote::BlendMode::DstAtop,
            CompositionStyle::Copy => raqote::BlendMode::Src,
            CompositionStyle::Lighter => raqote::BlendMode::Add,
            CompositionStyle::Xor => raqote::BlendMode::Xor,
            CompositionStyle::Clear => raqote::BlendMode::Clear,
        }
    }
}

impl SourceSurface {
    fn as_raqote(&self) -> &Vec<u8> {
        match self {
            SourceSurface::Raqote(s) => s,
        }
    }
}

impl GradientStop {
    fn as_raqote(&self) -> &raqote::GradientStop {
        match self {
            GradientStop::Raqote(s) => s,
        }
    }
}