Struct Canvas

pub struct Canvas<P, Message, Theme = Theme, Renderer = Renderer<Renderer, Renderer>>
where
    Renderer: Renderer,
    P: Program<Message, Theme, Renderer>,
{ /* private fields */ }

A widget capable of drawing 2D graphics.

Example: Drawing a Simple Circle

use iced::mouse;
use iced::widget::canvas;
use iced::{Color, Rectangle, Renderer, Theme};

// First, we define the data we need for drawing
#[derive(Debug)]
struct Circle {
    radius: f32,
}

// Then, we implement the `Program` trait
impl<Message> canvas::Program<Message> for Circle {
    // No internal state
    type State = ();

    fn draw(
        &self,
        _state: &(),
        renderer: &Renderer,
        _theme: &Theme,
        bounds: Rectangle,
        _cursor: mouse::Cursor
    ) -> Vec<canvas::Geometry> {
        // We prepare a new `Frame`
        let mut frame = canvas::Frame::new(renderer, bounds.size());

        // We create a `Path` representing a simple circle
        let circle = canvas::Path::circle(frame.center(), self.radius);

        // And fill it with some color
        frame.fill(&circle, Color::BLACK);

        // Then, we produce the geometry
        vec![frame.into_geometry()]
    }
}

// Finally, we simply use our `Circle` to create the `Canvas`!
fn view<'a, Message: 'a>(_state: &'a State) -> Element<'a, Message> {
    canvas(Circle { radius: 50.0 }).into()
}

Implementations

impl<P, Message, Theme, Renderer> Canvas<P, Message, Theme, Renderer>

where P: Program<Message, Theme, Renderer>, Renderer: Renderer,

pub fn new(program: P) -> Canvas<P, Message, Theme, Renderer>

Creates a new Canvas.

pub fn width( self, width: impl Into<Length>, ) -> Canvas<P, Message, Theme, Renderer>

Sets the width of the Canvas.

pub fn height( self, height: impl Into<Length>, ) -> Canvas<P, Message, Theme, Renderer>

Sets the height of the Canvas.

Trait Implementations

impl<P, Message, Theme, Renderer> Debug for Canvas<P, Message, Theme, Renderer>

where P: Debug + Program<Message, Theme, Renderer>, Message: Debug, Theme: Debug, Renderer: Debug + Renderer,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'a, P, Message, Theme, Renderer> From<Canvas<P, Message, Theme, Renderer>> for Element<'a, Message, Theme, Renderer>

where Message: 'a, Theme: 'a, Renderer: 'a + Renderer, P: 'a + Program<Message, Theme, Renderer>,

fn from( canvas: Canvas<P, Message, Theme, Renderer>, ) -> Element<'a, Message, Theme, Renderer>

Converts to this type from the input type.

impl<P, Message, Theme, Renderer> Widget<Message, Theme, Renderer> for Canvas<P, Message, Theme, Renderer>

where Renderer: Renderer, P: Program<Message, Theme, Renderer>,

fn tag(&self) -> Tag

Returns the Tag of the Widget.

fn state(&self) -> State

Returns the State of the Widget.

fn size(&self) -> Size<Length>

Returns the Size of the Widget in lengths.

fn layout( &self, _tree: &mut Tree, _renderer: &Renderer, limits: &Limits, ) -> Node

Returns the layout::Node of the Widget.

fn update( &mut self, tree: &mut Tree, event: &Event, layout: Layout<'_>, cursor: Cursor, renderer: &Renderer, _clipboard: &mut dyn Clipboard, shell: &mut Shell<'_, Message>, viewport: &Rectangle, )

Processes a runtime Event.

fn mouse_interaction( &self, tree: &Tree, layout: Layout<'_>, cursor: Cursor, _viewport: &Rectangle, _renderer: &Renderer, ) -> Interaction

Returns the current mouse::Interaction of the Widget.

fn draw( &self, tree: &Tree, renderer: &mut Renderer, theme: &Theme, _style: &Style, layout: Layout<'_>, cursor: Cursor, _viewport: &Rectangle, )

Draws the Widget using the associated Renderer.

fn size_hint(&self) -> Size<Length>

Returns a Size hint for laying out the Widget.

fn children(&self) -> Vec<Tree>

Returns the state Tree of the children of the Widget.

fn diff(&self, tree: &mut Tree)

Reconciles the Widget with the provided Tree.

fn operate( &self, _state: &mut Tree, _layout: Layout<'_>, _renderer: &Renderer, _operation: &mut dyn Operation, )

Applies an Operation to the Widget.

fn overlay<'a>( &'a mut self, _state: &'a mut Tree, _layout: Layout<'a>, _renderer: &Renderer, _viewport: &Rectangle, _translation: Vector, ) -> Option<Element<'a, Message, Theme, Renderer>>

Returns the overlay of the Widget, if there is any.