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