Implement `Canvas` support for `iced_tiny_skia`

6 files changed, 411 insertions, 9 deletions

diff --git a/tiny_skia/Cargo.toml b/tiny_skia/Cargo.toml
index 781e7d34..5f39fce2 100644
--- a/tiny_skia/Cargo.toml
+++ b/tiny_skia/Cargo.toml
@@ -6,6 +6,7 @@ edition = "2021"
 [features]
 image = []
 svg = []
+canvas = ["iced_native/canvas"]
 
 [dependencies]
 raw-window-handle = "0.5"
diff --git a/tiny_skia/src/backend.rs b/tiny_skia/src/backend.rs
index 66d83221..e08cede7 100644
--- a/tiny_skia/src/backend.rs
+++ b/tiny_skia/src/backend.rs
@@ -1,9 +1,9 @@
-use crate::{Color, Font, Settings, Size, Viewport};
+use crate::{Color, Font, Primitive, Settings, Size, Viewport};
 
 use iced_graphics::alignment;
 use iced_graphics::backend;
 use iced_graphics::text;
-use iced_graphics::{Background, Primitive, Rectangle, Vector};
+use iced_graphics::{Background, Rectangle, Vector};
 
 use std::borrow::Cow;
 
@@ -81,7 +81,6 @@ impl Backend {
         translation: Vector,
     ) {
         match primitive {
-            Primitive::None => {}
             Primitive::Quad {
                 bounds,
                 background,
@@ -161,6 +160,38 @@ impl Backend {
             Primitive::Svg { .. } => {
                 // TODO
             }
+            Primitive::Fill {
+                path,
+                paint,
+                rule,
+                transform,
+            } => {
+                pixels.fill_path(
+                    path,
+                    paint,
+                    *rule,
+                    transform
+                        .post_translate(translation.x, translation.y)
+                        .post_scale(scale_factor, scale_factor),
+                    clip_mask,
+                );
+            }
+            Primitive::Stroke {
+                path,
+                paint,
+                stroke,
+                transform,
+            } => {
+                pixels.stroke_path(
+                    path,
+                    paint,
+                    stroke,
+                    transform
+                        .post_translate(translation.x, translation.y)
+                        .post_scale(scale_factor, scale_factor),
+                    clip_mask,
+                );
+            }
             Primitive::Group { primitives } => {
                 for primitive in primitives {
                     self.draw_primitive(
@@ -196,16 +227,19 @@ impl Backend {
                     translation,
                 );
             }
-            Primitive::Cached { cache } => {
+            Primitive::Cache { content } => {
                 self.draw_primitive(
-                    cache,
+                    content,
                     pixels,
                     clip_mask,
                     scale_factor,
                     translation,
                 );
             }
-            Primitive::SolidMesh { .. } | Primitive::GradientMesh { .. } => {}
+            Primitive::SolidMesh { .. } | Primitive::GradientMesh { .. } => {
+                // Not supported!
+                // TODO: Draw a placeholder (?) / Log it (?)
+            }
         }
     }
 }
@@ -386,6 +420,8 @@ fn rectangular_clip_mask(
 }
 
 impl iced_graphics::Backend for Backend {
+    type Geometry = ();
+
     fn trim_measurements(&mut self) {
         self.text_pipeline.trim_measurement_cache();
     }
diff --git a/tiny_skia/src/canvas.rs b/tiny_skia/src/canvas.rs
new file mode 100644
index 00000000..c3b8b316
--- /dev/null
+++ b/tiny_skia/src/canvas.rs
@@ -0,0 +1,276 @@
+use crate::{Point, Primitive, Rectangle, Size, Vector};
+
+use iced_native::widget::canvas::fill::{self, Fill};
+use iced_native::widget::canvas::stroke::{self, Stroke};
+use iced_native::widget::canvas::{Path, Style, Text};
+use iced_native::Gradient;
+
+pub struct Frame {
+    size: Size,
+    transform: tiny_skia::Transform,
+    stack: Vec<tiny_skia::Transform>,
+    primitives: Vec<Primitive>,
+}
+
+impl Frame {
+    pub fn new(size: Size) -> Self {
+        Self {
+            size,
+            transform: tiny_skia::Transform::identity(),
+            stack: Vec::new(),
+            primitives: Vec::new(),
+        }
+    }
+
+    pub fn width(&self) -> f32 {
+        self.size.width
+    }
+
+    pub fn height(&self) -> f32 {
+        self.size.height
+    }
+
+    pub fn size(&self) -> Size {
+        self.size
+    }
+
+    pub fn center(&self) -> Point {
+        Point::new(self.size.width / 2.0, self.size.height / 2.0)
+    }
+
+    pub fn fill(&mut self, path: &Path, fill: impl Into<Fill>) {
+        let path = convert_path(path);
+        let fill = fill.into();
+
+        self.primitives.push(Primitive::Fill {
+            path,
+            paint: into_paint(fill.style),
+            rule: into_fill_rule(fill.rule),
+            transform: self.transform,
+        });
+    }
+
+    pub fn fill_rectangle(
+        &mut self,
+        top_left: Point,
+        size: Size,
+        fill: impl Into<Fill>,
+    ) {
+        self.fill(&Path::rectangle(top_left, size), fill);
+    }
+
+    pub fn stroke<'a>(&mut self, path: &Path, stroke: impl Into<Stroke<'a>>) {
+        let path = convert_path(path);
+        let stroke = stroke.into();
+        let skia_stroke = into_stroke(&stroke);
+
+        self.primitives.push(Primitive::Stroke {
+            path,
+            paint: into_paint(stroke.style),
+            stroke: skia_stroke,
+            transform: self.transform,
+        });
+    }
+
+    pub fn fill_text(&mut self, text: impl Into<Text>) {
+        let text = text.into();
+
+        let position = if self.transform.is_identity() {
+            text.position
+        } else {
+            let mut transformed = [tiny_skia::Point {
+                x: text.position.x,
+                y: text.position.y,
+            }];
+
+            self.transform.map_points(&mut transformed);
+
+            Point::new(transformed[0].x, transformed[0].y)
+        };
+
+        // TODO: Use vectorial text instead of primitive
+        self.primitives.push(Primitive::Text {
+            content: text.content,
+            bounds: Rectangle {
+                x: position.x,
+                y: position.y,
+                width: f32::INFINITY,
+                height: f32::INFINITY,
+            },
+            color: text.color,
+            size: text.size,
+            font: text.font,
+            horizontal_alignment: text.horizontal_alignment,
+            vertical_alignment: text.vertical_alignment,
+        });
+    }
+
+    pub fn push_transform(&mut self) {
+        self.stack.push(self.transform);
+    }
+
+    pub fn pop_transform(&mut self) {
+        self.transform = self.stack.pop().expect("Pop transform");
+    }
+
+    pub fn clip(&mut self, _frame: Self, _translation: Vector) {}
+
+    pub fn translate(&mut self, translation: Vector) {
+        self.transform =
+            self.transform.pre_translate(translation.x, translation.y);
+    }
+
+    pub fn rotate(&mut self, angle: f32) {
+        self.transform = self
+            .transform
+            .pre_concat(tiny_skia::Transform::from_rotate(angle.to_degrees()));
+    }
+
+    pub fn scale(&mut self, scale: f32) {
+        self.transform = self.transform.pre_scale(scale, scale);
+    }
+
+    pub fn into_primitive(self) -> Primitive {
+        Primitive::Clip {
+            bounds: Rectangle::new(Point::ORIGIN, self.size),
+            content: Box::new(Primitive::Group {
+                primitives: self.primitives,
+            }),
+        }
+    }
+}
+
+fn convert_path(path: &Path) -> tiny_skia::Path {
+    use iced_native::widget::canvas::path::lyon_path;
+
+    let mut builder = tiny_skia::PathBuilder::new();
+    let mut last_point = Default::default();
+
+    for event in path.raw().iter() {
+        match event {
+            lyon_path::Event::Begin { at } => {
+                builder.move_to(at.x, at.y);
+
+                last_point = at;
+            }
+            lyon_path::Event::Line { from, to } => {
+                if last_point != from {
+                    builder.move_to(from.x, from.y);
+                }
+
+                builder.line_to(to.x, to.y);
+
+                last_point = to;
+            }
+            lyon_path::Event::Quadratic { from, ctrl, to } => {
+                if last_point != from {
+                    builder.move_to(from.x, from.y);
+                }
+
+                builder.quad_to(ctrl.x, ctrl.y, to.x, to.y);
+
+                last_point = to;
+            }
+            lyon_path::Event::Cubic {
+                from,
+                ctrl1,
+                ctrl2,
+                to,
+            } => {
+                if last_point != from {
+                    builder.move_to(from.x, from.y);
+                }
+
+                builder
+                    .cubic_to(ctrl1.x, ctrl1.y, ctrl2.x, ctrl2.y, to.x, to.y);
+
+                last_point = to;
+            }
+            lyon_path::Event::End { close, .. } => {
+                if close {
+                    builder.close();
+                }
+            }
+        }
+    }
+
+    builder
+        .finish()
+        .expect("Convert lyon path to tiny_skia path")
+}
+
+pub fn into_paint(style: Style) -> tiny_skia::Paint<'static> {
+    tiny_skia::Paint {
+        shader: match style {
+            Style::Solid(color) => tiny_skia::Shader::SolidColor(
+                tiny_skia::Color::from_rgba(color.b, color.g, color.r, color.a)
+                    .expect("Create color"),
+            ),
+            Style::Gradient(gradient) => match gradient {
+                Gradient::Linear(linear) => tiny_skia::LinearGradient::new(
+                    tiny_skia::Point {
+                        x: linear.start.x,
+                        y: linear.start.y,
+                    },
+                    tiny_skia::Point {
+                        x: linear.end.x,
+                        y: linear.end.y,
+                    },
+                    linear
+                        .color_stops
+                        .into_iter()
+                        .map(|stop| {
+                            tiny_skia::GradientStop::new(
+                                stop.offset,
+                                tiny_skia::Color::from_rgba(
+                                    stop.color.b,
+                                    stop.color.g,
+                                    stop.color.r,
+                                    stop.color.a,
+                                )
+                                .expect("Create color"),
+                            )
+                        })
+                        .collect(),
+                    tiny_skia::SpreadMode::Pad,
+                    tiny_skia::Transform::identity(),
+                )
+                .expect("Create linear gradient"),
+            },
+        },
+        anti_alias: true,
+        ..Default::default()
+    }
+}
+
+pub fn into_fill_rule(rule: fill::Rule) -> tiny_skia::FillRule {
+    match rule {
+        fill::Rule::EvenOdd => tiny_skia::FillRule::EvenOdd,
+        fill::Rule::NonZero => tiny_skia::FillRule::Winding,
+    }
+}
+
+pub fn into_stroke(stroke: &Stroke) -> tiny_skia::Stroke {
+    tiny_skia::Stroke {
+        width: stroke.width,
+        line_cap: match stroke.line_cap {
+            stroke::LineCap::Butt => tiny_skia::LineCap::Butt,
+            stroke::LineCap::Square => tiny_skia::LineCap::Square,
+            stroke::LineCap::Round => tiny_skia::LineCap::Round,
+        },
+        line_join: match stroke.line_join {
+            stroke::LineJoin::Miter => tiny_skia::LineJoin::Miter,
+            stroke::LineJoin::Round => tiny_skia::LineJoin::Round,
+            stroke::LineJoin::Bevel => tiny_skia::LineJoin::Bevel,
+        },
+        dash: if stroke.line_dash.segments.is_empty() {
+            None
+        } else {
+            tiny_skia::StrokeDash::new(
+                stroke.line_dash.segments.into(),
+                stroke.line_dash.offset as f32,
+            )
+        },
+        ..Default::default()
+    }
+}
diff --git a/tiny_skia/src/lib.rs b/tiny_skia/src/lib.rs
index 420a1ffb..e66e6412 100644
--- a/tiny_skia/src/lib.rs
+++ b/tiny_skia/src/lib.rs
@@ -4,10 +4,18 @@ mod backend;
 mod settings;
 mod text;
 
+#[cfg(feature = "canvas")]
+pub mod canvas;
+
+pub use iced_graphics::primitive;
+
 pub use backend::Backend;
+pub use primitive::Primitive;
 pub use settings::Settings;
 
-pub use iced_graphics::{Color, Error, Font, Point, Size, Vector, Viewport};
+pub use iced_graphics::{
+    Color, Error, Font, Point, Rectangle, Size, Vector, Viewport,
+};
 
 /// A [`tiny-skia`] graphics renderer for [`iced`].
 ///
diff --git a/tiny_skia/src/primitive.rs b/tiny_skia/src/primitive.rs
new file mode 100644
index 00000000..22daaedc
--- /dev/null
+++ b/tiny_skia/src/primitive.rs
@@ -0,0 +1,82 @@
+use crate::{Rectangle, Vector};
+
+use std::sync::Arc;
+
+#[derive(Debug, Clone)]
+pub enum Primitive {
+    /// A group of primitives
+    Group {
+        /// The primitives of the group
+        primitives: Vec<Primitive>,
+    },
+    /// A clip primitive
+    Clip {
+        /// The bounds of the clip
+        bounds: Rectangle,
+        /// The content of the clip
+        content: Box<Primitive>,
+    },
+    /// A primitive that applies a translation
+    Translate {
+        /// The translation vector
+        translation: Vector,
+
+        /// The primitive to translate
+        content: Box<Primitive>,
+    },
+    /// A cached primitive.
+    ///
+    /// This can be useful if you are implementing a widget where primitive
+    /// generation is expensive.
+    Cached {
+        /// The cached primitive
+        cache: Arc<Primitive>,
+    },
+    /// A basic primitive.
+    Basic(iced_graphics::Primitive),
+}
+
+impl iced_graphics::backend::Primitive for Primitive {
+    fn translate(self, translation: Vector) -> Self {
+        Self::Translate {
+            translation,
+            content: Box::new(self),
+        }
+    }
+
+    fn clip(self, bounds: Rectangle) -> Self {
+        Self::Clip {
+            bounds,
+            content: Box::new(self),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Default)]
+pub struct Recording(pub(crate) Vec<Primitive>);
+
+impl iced_graphics::backend::Recording for Recording {
+    type Primitive = Primitive;
+
+    fn push(&mut self, primitive: Primitive) {
+        self.0.push(primitive);
+    }
+
+    fn push_basic(&mut self, basic: iced_graphics::Primitive) {
+        self.0.push(Primitive::Basic(basic));
+    }
+
+    fn group(self) -> Self::Primitive {
+        Primitive::Group { primitives: self.0 }
+    }
+
+    fn clear(&mut self) {
+        self.0.clear();
+    }
+}
+
+impl Recording {
+    pub fn primitives(&self) -> &[Primitive] {
+        &self.0
+    }
+}
diff --git a/tiny_skia/src/window/compositor.rs b/tiny_skia/src/window/compositor.rs
index 2bd5831e..08159cd8 100644
--- a/tiny_skia/src/window/compositor.rs
+++ b/tiny_skia/src/window/compositor.rs
@@ -1,7 +1,6 @@
-use crate::{Backend, Color, Error, Renderer, Settings, Viewport};
+use crate::{Backend, Color, Error, Primitive, Renderer, Settings, Viewport};
 
 use iced_graphics::window::compositor::{self, Information, SurfaceError};
-use iced_graphics::Primitive;
 
 use raw_window_handle::{HasRawDisplayHandle, HasRawWindowHandle};
 use std::marker::PhantomData;