Draft Canvas types and clock example

wgpu/src/widget/canvas.rs

@@ -1,5 +1,158 @@
 //! Draw freely in 2D.
+use crate::{Defaults, Primitive, Renderer};
+
+use iced_native::{
+    layout, Color, Element, Hasher, Layout, Length, MouseCursor, Point, Size,
+    Widget,
+};
+use std::hash::Hash;
+
+pub mod layer;
+pub mod path;
+
+mod data;
+mod frame;
+
+pub use data::Data;
+pub use frame::Frame;
+pub use layer::Layer;
+pub use path::Path;
 
 /// A 2D drawable region.
 #[derive(Debug)]
-pub struct Canvas;
+pub struct Canvas<'a> {
+    width: Length,
+    height: Length,
+    layers: Vec<Box<dyn Layer + 'a>>,
+}
+
+impl<'a> Canvas<'a> {
+    const DEFAULT_SIZE: u16 = 100;
+
+    pub fn new() -> Self {
+        Canvas {
+            width: Length::Units(Self::DEFAULT_SIZE),
+            height: Length::Units(Self::DEFAULT_SIZE),
+            layers: Vec::new(),
+        }
+    }
+
+    pub fn width(mut self, width: Length) -> Self {
+        self.width = width;
+        self
+    }
+
+    pub fn height(mut self, height: Length) -> Self {
+        self.height = height;
+        self
+    }
+
+    pub fn push(mut self, layer: impl Layer + 'a) -> Self {
+        self.layers.push(Box::new(layer));
+        self
+    }
+}
+
+impl<'a, Message> Widget<Message, Renderer> for Canvas<'a> {
+    fn width(&self) -> Length {
+        self.width
+    }
+
+    fn height(&self) -> Length {
+        self.height
+    }
+
+    fn layout(
+        &self,
+        _renderer: &Renderer,
+        limits: &layout::Limits,
+    ) -> layout::Node {
+        let limits = limits.width(self.width).height(self.height);
+
+        let size = limits.resolve(Size::ZERO);
+
+        layout::Node::new(size)
+    }
+
+    fn draw(
+        &self,
+        _renderer: &mut Renderer,
+        _defaults: &Defaults,
+        _layout: Layout<'_>,
+        _cursor_position: Point,
+    ) -> (Primitive, MouseCursor) {
+        (Primitive::None, MouseCursor::Idle)
+    }
+
+    fn hash_layout(&self, state: &mut Hasher) {
+        std::any::TypeId::of::<Canvas<'static>>().hash(state);
+
+        self.width.hash(state);
+        self.height.hash(state);
+    }
+}
+
+impl<'a, Message> From<Canvas<'a>> for Element<'a, Message, Renderer>
+where
+    Message: 'static,
+{
+    fn from(canvas: Canvas<'a>) -> Element<'a, Message, Renderer> {
+        Element::new(canvas)
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct Stroke {
+    pub color: Color,
+    pub width: f32,
+    pub line_cap: LineCap,
+    pub line_join: LineJoin,
+}
+
+impl Default for Stroke {
+    fn default() -> Stroke {
+        Stroke {
+            color: Color::BLACK,
+            width: 1.0,
+            line_cap: LineCap::default(),
+            line_join: LineJoin::default(),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum LineCap {
+    Butt,
+    Square,
+    Round,
+}
+
+impl Default for LineCap {
+    fn default() -> LineCap {
+        LineCap::Butt
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum LineJoin {
+    Miter,
+    Round,
+    Bevel,
+}
+
+impl Default for LineJoin {
+    fn default() -> LineJoin {
+        LineJoin::Miter
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum Fill {
+    Color(Color),
+}
+
+impl Default for Fill {
+    fn default() -> Fill {
+        Fill::Color(Color::BLACK)
+    }
+}

wgpu/src/widget/canvas/data.rs

@@ -0,0 +1,20 @@
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
+pub struct Data<T> {
+    raw: T,
+    version: usize,
+}
+
+impl<T> Data<T> {
+    pub fn new(data: T) -> Self {
+        Data {
+            raw: data,
+            version: 0,
+        }
+    }
+
+    pub fn update(&mut self, f: impl FnOnce(&mut T)) {
+        f(&mut self.raw);
+
+        self.version += 1;
+    }
+}

wgpu/src/widget/canvas/frame.rs

@@ -0,0 +1,39 @@
+use iced_native::Point;
+
+use crate::{
+    canvas::{Fill, Path, Stroke},
+    triangle,
+};
+
+#[derive(Debug)]
+pub struct Frame {
+    width: u32,
+    height: u32,
+    buffers: lyon::tessellation::VertexBuffers<triangle::Vertex2D, u16>,
+}
+
+impl Frame {
+    pub(crate) fn new(width: u32, height: u32) -> Frame {
+        Frame {
+            width,
+            height,
+            buffers: lyon::tessellation::VertexBuffers::new(),
+        }
+    }
+
+    pub fn width(&self) -> u32 {
+        self.width
+    }
+
+    pub fn height(&self) -> u32 {
+        self.height
+    }
+
+    pub fn center(&self) -> Point {
+        Point::new(self.width as f32 / 2.0, self.height as f32 / 2.0)
+    }
+
+    pub fn fill(&mut self, path: Path, fill: Fill) {}
+
+    pub fn stroke(&mut self, path: Path, stroke: Stroke) {}
+}

wgpu/src/widget/canvas/layer.rs

@@ -0,0 +1,41 @@
+use crate::canvas::Frame;
+
+pub trait Layer: std::fmt::Debug {}
+
+use std::marker::PhantomData;
+use std::sync::{Arc, Weak};
+
+#[derive(Debug)]
+pub struct Cached<T: Drawable> {
+    input: PhantomData<T>,
+}
+
+impl<T> Cached<T>
+where
+    T: Drawable + std::fmt::Debug,
+{
+    pub fn new() -> Self {
+        Cached { input: PhantomData }
+    }
+
+    pub fn clear(&mut self) {}
+
+    pub fn with<'a>(&'a self, input: &'a T) -> impl Layer + 'a {
+        Bind {
+            cache: self,
+            input: input,
+        }
+    }
+}
+
+#[derive(Debug)]
+struct Bind<'a, T: Drawable> {
+    cache: &'a Cached<T>,
+    input: &'a T,
+}
+
+impl<'a, T> Layer for Bind<'a, T> where T: Drawable + std::fmt::Debug {}
+
+pub trait Drawable {
+    fn draw(&self, frame: &mut Frame);
+}

wgpu/src/widget/canvas/path.rs

@@ -0,0 +1,78 @@
+use iced_native::{Point, Vector};
+
+#[allow(missing_debug_implementations)]
+pub struct Path {
+    raw: lyon::path::Builder,
+}
+
+impl Path {
+    pub fn new() -> Path {
+        Path {
+            raw: lyon::path::Path::builder(),
+        }
+    }
+
+    #[inline]
+    pub fn move_to(&mut self, point: Point) {
+        let _ = self.raw.move_to(lyon::math::Point::new(point.x, point.y));
+    }
+
+    #[inline]
+    pub fn line_to(&mut self, point: Point) {
+        let _ = self.raw.line_to(lyon::math::Point::new(point.x, point.y));
+    }
+
+    #[inline]
+    pub fn arc(&mut self, arc: Arc) {
+        self.ellipse(arc.into())
+    }
+
+    #[inline]
+    pub fn ellipse(&mut self, ellipse: Ellipse) {
+        let arc = lyon::geom::Arc {
+            center: lyon::math::Point::new(ellipse.center.x, ellipse.center.y),
+            radii: lyon::math::Vector::new(ellipse.radii.x, ellipse.radii.y),
+            x_rotation: lyon::math::Angle::radians(ellipse.rotation),
+            start_angle: lyon::math::Angle::radians(ellipse.start_angle),
+            sweep_angle: lyon::math::Angle::radians(ellipse.end_angle),
+        };
+
+        arc.for_each_quadratic_bezier(&mut |curve| {
+            let _ = self.raw.quadratic_bezier_to(curve.ctrl, curve.to);
+        });
+    }
+
+    #[inline]
+    pub fn close(&mut self) {
+        self.raw.close()
+    }
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct Arc {
+    pub center: Point,
+    pub radius: f32,
+    pub start_angle: f32,
+    pub end_angle: f32,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct Ellipse {
+    pub center: Point,
+    pub radii: Vector,
+    pub rotation: f32,
+    pub start_angle: f32,
+    pub end_angle: f32,
+}
+
+impl From<Arc> for Ellipse {
+    fn from(arc: Arc) -> Ellipse {
+        Ellipse {
+            center: arc.center,
+            radii: Vector::new(arc.radius, arc.radius),
+            rotation: 0.0,
+            start_angle: arc.start_angle,
+            end_angle: arc.end_angle,
+        }
+    }
+}