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Diffstat (limited to 'glow/src/widget/canvas.rs')
-rw-r--r-- | glow/src/widget/canvas.rs | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/glow/src/widget/canvas.rs b/glow/src/widget/canvas.rs new file mode 100644 index 00000000..325f90ce --- /dev/null +++ b/glow/src/widget/canvas.rs @@ -0,0 +1,201 @@ +//! Draw 2D graphics for your users. +//! +//! A [`Canvas`] widget can be used to draw different kinds of 2D shapes in a +//! [`Frame`]. It can be used for animation, data visualization, game graphics, +//! and more! +//! +//! [`Canvas`]: struct.Canvas.html +//! [`Frame`]: struct.Frame.html +use crate::{Defaults, Primitive, Renderer}; + +use iced_native::{ + layout, Element, Hasher, Layout, Length, MouseCursor, Point, Size, Widget, +}; +use std::hash::Hash; + +pub mod layer; +pub mod path; + +mod drawable; +mod fill; +mod frame; +mod stroke; +mod text; + +pub use drawable::Drawable; +pub use fill::Fill; +pub use frame::Frame; +pub use layer::Layer; +pub use path::Path; +pub use stroke::{LineCap, LineJoin, Stroke}; +pub use text::Text; + +/// A widget capable of drawing 2D graphics. +/// +/// A [`Canvas`] may contain multiple layers. A [`Layer`] is drawn using the +/// painter's algorithm. In other words, layers will be drawn on top of each +/// other in the same order they are pushed into the [`Canvas`]. +/// +/// [`Canvas`]: struct.Canvas.html +/// [`Layer`]: layer/trait.Layer.html +/// +/// # Examples +/// The repository has a couple of [examples] showcasing how to use a +/// [`Canvas`]: +/// +/// - [`clock`], an application that uses the [`Canvas`] widget to draw a clock +/// and its hands to display the current time. +/// - [`solar_system`], an animated solar system drawn using the [`Canvas`] widget +/// and showcasing how to compose different transforms. +/// +/// [examples]: https://github.com/hecrj/iced/tree/0.1/examples +/// [`clock`]: https://github.com/hecrj/iced/tree/0.1/examples/clock +/// [`solar_system`]: https://github.com/hecrj/iced/tree/0.1/examples/solar_system +/// +/// ## Drawing a simple circle +/// If you want to get a quick overview, here's how we can draw a simple circle: +/// +/// ```no_run +/// # mod iced { +/// # pub use iced_wgpu::canvas; +/// # pub use iced_native::Color; +/// # } +/// use iced::canvas::{self, layer, Canvas, Drawable, Fill, Frame, Path}; +/// use iced::Color; +/// +/// // First, we define the data we need for drawing +/// #[derive(Debug)] +/// struct Circle { +/// radius: f32, +/// } +/// +/// // Then, we implement the `Drawable` trait +/// impl Drawable for Circle { +/// fn draw(&self, frame: &mut Frame) { +/// // We create a `Path` representing a simple circle +/// let circle = Path::new(|p| p.circle(frame.center(), self.radius)); +/// +/// // And fill it with some color +/// frame.fill(&circle, Fill::Color(Color::BLACK)); +/// } +/// } +/// +/// // We can use a `Cache` to avoid unnecessary re-tessellation +/// let cache: layer::Cache<Circle> = layer::Cache::new(); +/// +/// // Finally, we simply provide the data to our `Cache` and push the resulting +/// // layer into a `Canvas` +/// let canvas = Canvas::new() +/// .push(cache.with(&Circle { radius: 50.0 })); +/// ``` +#[derive(Debug)] +pub struct Canvas<'a> { + width: Length, + height: Length, + layers: Vec<Box<dyn Layer + 'a>>, +} + +impl<'a> Canvas<'a> { + const DEFAULT_SIZE: u16 = 100; + + /// Creates a new [`Canvas`] with no layers. + /// + /// [`Canvas`]: struct.Canvas.html + pub fn new() -> Self { + Canvas { + width: Length::Units(Self::DEFAULT_SIZE), + height: Length::Units(Self::DEFAULT_SIZE), + layers: Vec::new(), + } + } + + /// Sets the width of the [`Canvas`]. + /// + /// [`Canvas`]: struct.Canvas.html + pub fn width(mut self, width: Length) -> Self { + self.width = width; + self + } + + /// Sets the height of the [`Canvas`]. + /// + /// [`Canvas`]: struct.Canvas.html + pub fn height(mut self, height: Length) -> Self { + self.height = height; + self + } + + /// Adds a [`Layer`] to the [`Canvas`]. + /// + /// It will be drawn on top of previous layers. + /// + /// [`Layer`]: layer/trait.Layer.html + /// [`Canvas`]: struct.Canvas.html + 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) { + let bounds = layout.bounds(); + let origin = Point::new(bounds.x, bounds.y); + let size = Size::new(bounds.width, bounds.height); + + ( + Primitive::Group { + primitives: self + .layers + .iter() + .map(|layer| Primitive::Cached { + origin, + cache: layer.draw(size), + }) + .collect(), + }, + 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) + } +} |