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use crate::overlay;
use crate::widget::tree::{self, Tree};
use crate::widget::Widget;
use iced_native::event::{self, Event};
use iced_native::layout::{self, Layout};
use iced_native::mouse;
use iced_native::renderer;
use iced_native::{Clipboard, Length, Point, Rectangle, Shell};
use std::borrow::Borrow;
/// A generic [`Widget`].
///
/// It is useful to build composable user interfaces that do not leak
/// implementation details in their __view logic__.
///
/// If you have a [built-in widget], you should be able to use `Into<Element>`
/// to turn it into an [`Element`].
///
/// [built-in widget]: crate::widget
pub struct Element<'a, Message, Renderer> {
widget: Box<dyn Widget<Message, Renderer> + 'a>,
}
impl<'a, Message, Renderer> Element<'a, Message, Renderer> {
/// Creates a new [`Element`] containing the given [`Widget`].
pub fn new(widget: impl Widget<Message, Renderer> + 'a) -> Self {
Self {
widget: Box::new(widget),
}
}
/// Returns a reference to the [`Widget`] of the [`Element`],
pub fn as_widget(&self) -> &dyn Widget<Message, Renderer> {
self.widget.as_ref()
}
/// Returns a mutable reference to the [`Widget`] of the [`Element`],
pub fn as_widget_mut(&mut self) -> &mut dyn Widget<Message, Renderer> {
self.widget.as_mut()
}
/// Applies a transformation to the produced message of the [`Element`].
///
/// This method is useful when you want to decouple different parts of your
/// UI and make them __composable__.
///
/// # Example
/// Imagine we want to use [our counter](index.html#usage). But instead of
/// showing a single counter, we want to display many of them. We can reuse
/// the `Counter` type as it is!
///
/// We use composition to model the __state__ of our new application:
///
/// ```
/// # mod counter {
/// # pub struct Counter;
/// # }
/// use counter::Counter;
///
/// struct ManyCounters {
/// counters: Vec<Counter>,
/// }
/// ```
///
/// We can store the state of multiple counters now. However, the
/// __messages__ we implemented before describe the user interactions
/// of a __single__ counter. Right now, we need to also identify which
/// counter is receiving user interactions. Can we use composition again?
/// Yes.
///
/// ```
/// # mod counter {
/// # #[derive(Debug, Clone, Copy)]
/// # pub enum Message {}
/// # }
/// #[derive(Debug, Clone, Copy)]
/// pub enum Message {
/// Counter(usize, counter::Message)
/// }
/// ```
///
/// We compose the previous __messages__ with the index of the counter
/// producing them. Let's implement our __view logic__ now:
///
/// ```
/// # mod counter {
/// # type Text = iced_pure::widget::Text<iced_native::renderer::Null>;
/// #
/// # #[derive(Debug, Clone, Copy)]
/// # pub enum Message {}
/// # pub struct Counter;
/// #
/// # impl Counter {
/// # pub fn view(&mut self) -> Text {
/// # Text::new("")
/// # }
/// # }
/// # }
/// #
/// # mod iced_wgpu {
/// # pub use iced_native::renderer::Null as Renderer;
/// # }
/// #
/// # use counter::Counter;
/// #
/// # struct ManyCounters {
/// # counters: Vec<Counter>,
/// # }
/// #
/// # #[derive(Debug, Clone, Copy)]
/// # pub enum Message {
/// # Counter(usize, counter::Message)
/// # }
/// use iced_pure::Element;
/// use iced_pure::widget::Row;
/// use iced_wgpu::Renderer;
///
/// impl ManyCounters {
/// pub fn view(&mut self) -> Row<Message, Renderer> {
/// // We can quickly populate a `Row` by folding over our counters
/// self.counters.iter_mut().enumerate().fold(
/// Row::new().spacing(20),
/// |row, (index, counter)| {
/// // We display the counter
/// let element: Element<counter::Message, Renderer> =
/// counter.view().into();
///
/// row.push(
/// // Here we turn our `Element<counter::Message>` into
/// // an `Element<Message>` by combining the `index` and the
/// // message of the `element`.
/// element.map(move |message| Message::Counter(index, message))
/// )
/// }
/// )
/// }
/// }
/// ```
///
/// Finally, our __update logic__ is pretty straightforward: simple
/// delegation.
///
/// ```
/// # mod counter {
/// # #[derive(Debug, Clone, Copy)]
/// # pub enum Message {}
/// # pub struct Counter;
/// #
/// # impl Counter {
/// # pub fn update(&mut self, _message: Message) {}
/// # }
/// # }
/// #
/// # use counter::Counter;
/// #
/// # struct ManyCounters {
/// # counters: Vec<Counter>,
/// # }
/// #
/// # #[derive(Debug, Clone, Copy)]
/// # pub enum Message {
/// # Counter(usize, counter::Message)
/// # }
/// impl ManyCounters {
/// pub fn update(&mut self, message: Message) {
/// match message {
/// Message::Counter(index, counter_msg) => {
/// if let Some(counter) = self.counters.get_mut(index) {
/// counter.update(counter_msg);
/// }
/// }
/// }
/// }
/// }
/// ```
pub fn map<B>(
self,
f: impl Fn(Message) -> B + 'a,
) -> Element<'a, B, Renderer>
where
Message: 'a,
Renderer: iced_native::Renderer + 'a,
B: 'a,
{
Element::new(Map::new(self.widget, f))
}
}
struct Map<'a, A, B, Renderer> {
widget: Box<dyn Widget<A, Renderer> + 'a>,
mapper: Box<dyn Fn(A) -> B + 'a>,
}
impl<'a, A, B, Renderer> Map<'a, A, B, Renderer> {
pub fn new<F>(
widget: Box<dyn Widget<A, Renderer> + 'a>,
mapper: F,
) -> Map<'a, A, B, Renderer>
where
F: 'a + Fn(A) -> B,
{
Map {
widget,
mapper: Box::new(mapper),
}
}
}
impl<'a, A, B, Renderer> Widget<B, Renderer> for Map<'a, A, B, Renderer>
where
Renderer: iced_native::Renderer + 'a,
A: 'a,
B: 'a,
{
fn tag(&self) -> tree::Tag {
self.widget.tag()
}
fn state(&self) -> tree::State {
self.widget.state()
}
fn children(&self) -> Vec<Tree> {
self.widget.children()
}
fn diff(&self, tree: &mut Tree) {
self.widget.diff(tree)
}
fn width(&self) -> Length {
self.widget.width()
}
fn height(&self) -> Length {
self.widget.height()
}
fn layout(
&self,
renderer: &Renderer,
limits: &layout::Limits,
) -> layout::Node {
self.widget.layout(renderer, limits)
}
fn on_event(
&mut self,
tree: &mut Tree,
event: Event,
layout: Layout<'_>,
cursor_position: Point,
renderer: &Renderer,
clipboard: &mut dyn Clipboard,
shell: &mut Shell<'_, B>,
) -> event::Status {
let mut local_messages = Vec::new();
let mut local_shell = Shell::new(&mut local_messages);
let status = self.widget.on_event(
tree,
event,
layout,
cursor_position,
renderer,
clipboard,
&mut local_shell,
);
shell.merge(local_shell, &self.mapper);
status
}
fn draw(
&self,
tree: &Tree,
renderer: &mut Renderer,
style: &renderer::Style,
layout: Layout<'_>,
cursor_position: Point,
viewport: &Rectangle,
) {
self.widget.draw(
tree,
renderer,
style,
layout,
cursor_position,
viewport,
)
}
fn mouse_interaction(
&self,
tree: &Tree,
layout: Layout<'_>,
cursor_position: Point,
viewport: &Rectangle,
renderer: &Renderer,
) -> mouse::Interaction {
self.widget.mouse_interaction(
tree,
layout,
cursor_position,
viewport,
renderer,
)
}
fn overlay<'b>(
&'b self,
tree: &'b mut Tree,
layout: Layout<'_>,
renderer: &Renderer,
) -> Option<overlay::Element<'b, B, Renderer>> {
let mapper = &self.mapper;
self.widget
.overlay(tree, layout, renderer)
.map(move |overlay| overlay.map(mapper))
}
}
impl<'a, Message, Renderer> Borrow<dyn Widget<Message, Renderer> + 'a>
for Element<'a, Message, Renderer>
{
fn borrow(&self) -> &(dyn Widget<Message, Renderer> + 'a) {
self.widget.borrow()
}
}
impl<'a, Message, Renderer> Borrow<dyn Widget<Message, Renderer> + 'a>
for &Element<'a, Message, Renderer>
{
fn borrow(&self) -> &(dyn Widget<Message, Renderer> + 'a) {
self.widget.borrow()
}
}