145 lines
4 KiB
Rust
145 lines
4 KiB
Rust
//! Create custom widgets and operate on them.
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pub mod operation;
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pub mod text;
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pub mod tree;
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mod id;
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pub use id::Id;
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pub use operation::Operation;
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pub use text::Text;
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pub use tree::Tree;
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use crate::event::{self, Event};
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use crate::layout::{self, Layout};
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use crate::mouse;
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use crate::overlay;
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use crate::renderer;
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use crate::{Clipboard, Length, Point, Rectangle, Shell};
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/// A component that displays information and allows interaction.
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///
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/// If you want to build your own widgets, you will need to implement this
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/// trait.
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///
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/// # Examples
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/// The repository has some [examples] showcasing how to implement a custom
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/// widget:
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///
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/// - [`bezier_tool`], a Paint-like tool for drawing Bézier curves using
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/// [`lyon`].
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/// - [`custom_widget`], a demonstration of how to build a custom widget that
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/// draws a circle.
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/// - [`geometry`], a custom widget showcasing how to draw geometry with the
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/// `Mesh2D` primitive in [`iced_wgpu`].
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///
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/// [examples]: https://github.com/iced-rs/iced/tree/0.9/examples
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/// [`bezier_tool`]: https://github.com/iced-rs/iced/tree/0.9/examples/bezier_tool
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/// [`custom_widget`]: https://github.com/iced-rs/iced/tree/0.9/examples/custom_widget
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/// [`geometry`]: https://github.com/iced-rs/iced/tree/0.9/examples/geometry
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/// [`lyon`]: https://github.com/nical/lyon
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/// [`iced_wgpu`]: https://github.com/iced-rs/iced/tree/0.9/wgpu
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pub trait Widget<Message, Renderer>
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where
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Renderer: crate::Renderer,
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{
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/// Returns the width of the [`Widget`].
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fn width(&self) -> Length;
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/// Returns the height of the [`Widget`].
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fn height(&self) -> Length;
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/// Returns the [`layout::Node`] of the [`Widget`].
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///
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/// This [`layout::Node`] is used by the runtime to compute the [`Layout`] of the
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/// user interface.
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fn layout(
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&self,
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renderer: &Renderer,
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limits: &layout::Limits,
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) -> layout::Node;
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/// Draws the [`Widget`] using the associated `Renderer`.
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fn draw(
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&self,
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state: &Tree,
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renderer: &mut Renderer,
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theme: &Renderer::Theme,
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style: &renderer::Style,
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layout: Layout<'_>,
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cursor_position: Point,
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viewport: &Rectangle,
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);
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/// Returns the [`Tag`] of the [`Widget`].
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///
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/// [`Tag`]: tree::Tag
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fn tag(&self) -> tree::Tag {
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tree::Tag::stateless()
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}
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/// Returns the [`State`] of the [`Widget`].
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///
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/// [`State`]: tree::State
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fn state(&self) -> tree::State {
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tree::State::None
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}
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/// Returns the state [`Tree`] of the children of the [`Widget`].
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fn children(&self) -> Vec<Tree> {
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Vec::new()
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}
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/// Reconciliates the [`Widget`] with the provided [`Tree`].
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fn diff(&self, _tree: &mut Tree) {}
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/// Applies an [`Operation`] to the [`Widget`].
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fn operate(
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&self,
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_state: &mut Tree,
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_layout: Layout<'_>,
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_renderer: &Renderer,
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_operation: &mut dyn Operation<Message>,
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) {
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}
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/// Processes a runtime [`Event`].
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///
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/// By default, it does nothing.
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fn on_event(
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&mut self,
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_state: &mut Tree,
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_event: Event,
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_layout: Layout<'_>,
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_cursor_position: Point,
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_renderer: &Renderer,
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_clipboard: &mut dyn Clipboard,
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_shell: &mut Shell<'_, Message>,
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) -> event::Status {
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event::Status::Ignored
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}
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/// Returns the current [`mouse::Interaction`] of the [`Widget`].
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///
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/// By default, it returns [`mouse::Interaction::Idle`].
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fn mouse_interaction(
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&self,
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_state: &Tree,
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_layout: Layout<'_>,
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_cursor_position: Point,
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_viewport: &Rectangle,
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_renderer: &Renderer,
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) -> mouse::Interaction {
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mouse::Interaction::Idle
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}
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/// Returns the overlay of the [`Widget`], if there is any.
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fn overlay<'a>(
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&'a mut self,
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_state: &'a mut Tree,
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_layout: Layout<'_>,
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_renderer: &Renderer,
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) -> Option<overlay::Element<'a, Message, Renderer>> {
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None
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}
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}
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