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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::mouse;
use crate::renderer;
use crate::widget::tree::{self, Tree};
use crate::{Clipboard, Layout, Point, Rectangle, Shell, 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,
theme: &Renderer::Theme,
style: &renderer::Style,
layout: Layout<'_>,
cursor_position: Point,
);
/// Returns the [`Tag`] of the [`Widget`].
///
/// [`Tag`]: tree::Tag
fn tag(&self) -> tree::Tag {
tree::Tag::stateless()
}
/// Returns the [`State`] of the [`Widget`].
///
/// [`State`]: tree::State
fn state(&self) -> tree::State {
tree::State::None
}
/// Returns the state [`Tree`] of the children of the [`Widget`].
fn children(&self) -> Vec<Tree> {
Vec::new()
}
/// Reconciliates the [`Widget`] with the provided [`Tree`].
fn diff(&self, _tree: &mut Tree) {}
/// 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,
_renderer: &Renderer,
_clipboard: &mut dyn Clipboard,
_shell: &mut Shell<'_, Message>,
) -> event::Status {
event::Status::Ignored
}
/// Returns the current [`mouse::Interaction`] of the [`Overlay`].
///
/// By default, it returns [`mouse::Interaction::Idle`].
fn mouse_interaction(
&self,
_layout: Layout<'_>,
_cursor_position: Point,
_viewport: &Rectangle,
_renderer: &Renderer,
) -> mouse::Interaction {
mouse::Interaction::Idle
}
}
/// Obtains the first overlay [`Element`] found in the given children.
///
/// This method will generally only be used by advanced users that are
/// implementing the [`Widget`](crate::Widget) trait.
pub fn from_children<'a, Message, Renderer>(
children: &'a [crate::Element<'_, Message, Renderer>],
tree: &'a mut Tree,
layout: Layout<'_>,
renderer: &Renderer,
) -> Option<Element<'a, Message, Renderer>>
where
Renderer: crate::Renderer,
{
children
.iter()
.zip(&mut tree.children)
.zip(layout.children())
.filter_map(|((child, state), layout)| {
child.as_widget().overlay(state, layout, renderer)
})
.next()
}
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