84 lines
2.6 KiB
Rust
84 lines
2.6 KiB
Rust
//! Display interactive elements on top of other widgets.
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mod element;
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pub mod menu;
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pub use element::Element;
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pub use menu::Menu;
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use crate::{layout, Clipboard, Event, Hasher, Layout, Point, Size};
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/// An interactive component that can be displayed on top of other widgets.
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pub trait Overlay<Message, Renderer>
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where
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Renderer: crate::Renderer,
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{
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/// Returns the layout [`Node`] of the [`Overlay`].
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///
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/// This [`Node`] is used by the runtime to compute the [`Layout`] of the
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/// user interface.
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///
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/// [`Node`]: ../layout/struct.Node.html
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/// [`Widget`]: trait.Overlay.html
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/// [`Layout`]: ../layout/struct.Layout.html
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fn layout(
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&self,
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renderer: &Renderer,
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bounds: Size,
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position: Point,
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) -> layout::Node;
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/// Draws the [`Overlay`] using the associated `Renderer`.
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///
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/// [`Overlay`]: trait.Overlay.html
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fn draw(
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&self,
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renderer: &mut Renderer,
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defaults: &Renderer::Defaults,
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layout: Layout<'_>,
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cursor_position: Point,
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) -> Renderer::Output;
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/// Computes the _layout_ hash of the [`Overlay`].
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///
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/// The produced hash is used by the runtime to decide if the [`Layout`]
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/// needs to be recomputed between frames. Therefore, to ensure maximum
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/// efficiency, the hash should only be affected by the properties of the
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/// [`Overlay`] that can affect layouting.
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///
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/// For example, the [`Text`] widget does not hash its color property, as
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/// its value cannot affect the overall [`Layout`] of the user interface.
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///
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/// [`Overlay`]: trait.Overlay.html
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/// [`Layout`]: ../layout/struct.Layout.html
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/// [`Text`]: text/struct.Text.html
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fn hash_layout(&self, state: &mut Hasher, position: Point);
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/// Processes a runtime [`Event`].
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///
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/// It receives:
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/// * an [`Event`] describing user interaction
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/// * the computed [`Layout`] of the [`Overlay`]
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/// * the current cursor position
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/// * a mutable `Message` list, allowing the [`Overlay`] to produce
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/// new messages based on user interaction.
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/// * the `Renderer`
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/// * a [`Clipboard`], if available
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///
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/// By default, it does nothing.
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///
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/// [`Event`]: ../enum.Event.html
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/// [`Overlay`]: trait.Widget.html
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/// [`Layout`]: ../layout/struct.Layout.html
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/// [`Clipboard`]: ../trait.Clipboard.html
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fn on_event(
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&mut self,
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_event: Event,
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_layout: Layout<'_>,
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_cursor_position: Point,
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_messages: &mut Vec<Message>,
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_renderer: &Renderer,
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_clipboard: Option<&dyn Clipboard>,
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) {
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}
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}
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