Trait iced::widget::canvas::Program

pub trait Program<Message, Theme = Theme> {
    type State: Default + 'static;

    fn draw(
        &self,
        state: &Self::State,
        theme: &Theme,
        bounds: Rectangle<f32>,
        cursor: Cursor
    ) -> Vec<Geometry, Global> ;

    fn update(
        &self,
        _state: &mut Self::State,
        _event: Event,
        _bounds: Rectangle<f32>,
        _cursor: Cursor
    ) -> (Status, Option<Message>) { ... }
    fn mouse_interaction(
        &self,
        _state: &Self::State,
        _bounds: Rectangle<f32>,
        _cursor: Cursor
    ) -> Interaction { ... }
}

Available on crate feature canvas only.

The state and logic of a Canvas.

A Program can mutate internal state and produce messages for an application.

Required Associated Types

type State: Default + 'static

The internal state mutated by the Program.

Required Methods

fn draw(
    &self,
    state: &Self::State,
    theme: &Theme,
    bounds: Rectangle<f32>,
    cursor: Cursor
) -> Vec<Geometry, Global>

Draws the state of the Program, producing a bunch of Geometry.

Geometry can be easily generated with a Frame or stored in a Cache.

Provided Methods

fn update(
    &self,
    _state: &mut Self::State,
    _event: Event,
    _bounds: Rectangle<f32>,
    _cursor: Cursor
) -> (Status, Option<Message>)

Updates the State of the Program.

When a Program is used in a Canvas, the runtime will call this method for each Event.

This method can optionally return a Message to notify an application of any meaningful interactions.

By default, this method does and returns nothing.

fn mouse_interaction(
    &self,
    _state: &Self::State,
    _bounds: Rectangle<f32>,
    _cursor: Cursor
) -> Interaction

Returns the current mouse interaction of the Program.

The interaction returned will be in effect even if the cursor position is out of bounds of the program’s Canvas.

Implementations on Foreign Types

impl<Message, Theme, T> Program<Message, Theme> for &Twhere
    T: Program<Message, Theme>,

type State = <T as Program<Message, Theme>>::State

fn update(
    &self,
    state: &mut <&T as Program<Message, Theme>>::State,
    event: Event,
    bounds: Rectangle<f32>,
    cursor: Cursor
) -> (Status, Option<Message>)

fn draw(
    &self,
    state: &<&T as Program<Message, Theme>>::State,
    theme: &Theme,
    bounds: Rectangle<f32>,
    cursor: Cursor
) -> Vec<Geometry, Global>

fn mouse_interaction(
    &self,
    state: &<&T as Program<Message, Theme>>::State,
    bounds: Rectangle<f32>,
    cursor: Cursor
) -> Interaction

Implementors