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)
+    }
+}