80 lines
2.3 KiB
Rust
80 lines
2.3 KiB
Rust
use crate::canvas::event::{self, Event};
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use crate::canvas::{Cursor, Geometry};
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use iced_native::{mouse, Rectangle};
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/// The state and logic of a [`Canvas`].
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///
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/// A [`Program`] can mutate internal state and produce messages for an
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/// application.
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///
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/// [`Canvas`]: crate::widget::Canvas
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pub trait Program<Message> {
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/// Updates the state of the [`Program`].
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///
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/// When a [`Program`] is used in a [`Canvas`], the runtime will call this
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/// method for each [`Event`].
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///
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/// This method can optionally return a `Message` to notify an application
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/// of any meaningful interactions.
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///
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/// By default, this method does and returns nothing.
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///
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/// [`Canvas`]: crate::widget::Canvas
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fn update(
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&mut self,
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_event: Event,
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_bounds: Rectangle,
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_cursor: Cursor,
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) -> (event::Status, Option<Message>) {
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(event::Status::Ignored, None)
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}
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/// Draws the state of the [`Program`], producing a bunch of [`Geometry`].
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///
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/// [`Geometry`] can be easily generated with a [`Frame`] or stored in a
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/// [`Cache`].
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///
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/// [`Frame`]: crate::widget::canvas::Frame
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/// [`Cache`]: crate::widget::canvas::Cache
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fn draw(&self, bounds: Rectangle, cursor: Cursor) -> Vec<Geometry>;
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/// Returns the current mouse interaction of the [`Program`].
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///
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/// The interaction returned will be in effect even if the cursor position
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/// is out of bounds of the program's [`Canvas`].
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///
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/// [`Canvas`]: crate::widget::Canvas
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fn mouse_interaction(
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&self,
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_bounds: Rectangle,
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_cursor: Cursor,
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) -> mouse::Interaction {
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mouse::Interaction::default()
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}
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}
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impl<T, Message> Program<Message> for &mut T
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where
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T: Program<Message>,
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{
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fn update(
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&mut self,
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event: Event,
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bounds: Rectangle,
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cursor: Cursor,
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) -> (event::Status, Option<Message>) {
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T::update(self, event, bounds, cursor)
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}
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fn draw(&self, bounds: Rectangle, cursor: Cursor) -> Vec<Geometry> {
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T::draw(self, bounds, cursor)
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}
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fn mouse_interaction(
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&self,
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bounds: Rectangle,
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cursor: Cursor,
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) -> mouse::Interaction {
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T::mouse_interaction(self, bounds, cursor)
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}
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}
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