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use crate::canvas::event::{self, Event};
use crate::canvas::{Cursor, Geometry};
use iced_native::{mouse, Rectangle};
/// The state and logic of a [`Canvas`].
///
/// A [`Program`] can mutate internal state and produce messages for an
/// application.
///
/// [`Canvas`]: crate::widget::Canvas
pub trait Program<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.
///
/// [`Canvas`]: crate::widget::Canvas
fn update(
&mut self,
_event: Event,
_bounds: Rectangle,
_cursor: Cursor,
) -> (event::Status, Option<Message>) {
(event::Status::Ignored, None)
}
/// Draws the state of the [`Program`], producing a bunch of [`Geometry`].
///
/// [`Geometry`] can be easily generated with a [`Frame`] or stored in a
/// [`Cache`].
///
/// [`Frame`]: crate::widget::canvas::Cache
/// [`Cache`]: crate::widget::canvas::Cache
fn draw(&self, bounds: Rectangle, cursor: Cursor) -> Vec<Geometry>;
/// 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`].
///
/// [`Canvas`]: crate::widget::Canvas
fn mouse_interaction(
&self,
_bounds: Rectangle,
_cursor: Cursor,
) -> mouse::Interaction {
mouse::Interaction::default()
}
}
impl<T, Message> Program<Message> for &mut T
where
T: Program<Message>,
{
fn update(
&mut self,
event: Event,
bounds: Rectangle,
cursor: Cursor,
) -> (event::Status, Option<Message>) {
T::update(self, event, bounds, cursor)
}
fn draw(&self, bounds: Rectangle, cursor: Cursor) -> Vec<Geometry> {
T::draw(self, bounds, cursor)
}
fn mouse_interaction(
&self,
bounds: Rectangle,
cursor: Cursor,
) -> mouse::Interaction {
T::mouse_interaction(self, bounds, cursor)
}
}
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