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//! Implement your own event loop to drive a user interface.
use iced_core::clipboard::DndDestinationRectangles;
use iced_core::widget::tree::NAMED;
use crate::core::event::{self, Event};
use crate::core::layout;
use crate::core::mouse;
use crate::core::renderer;
use crate::core::widget;
use crate::core::window;
use crate::core::{Clipboard, Element, Layout, Rectangle, Shell, Size, Vector};
use crate::overlay;
/// A set of interactive graphical elements with a specific [`Layout`].
///
/// It can be updated and drawn.
///
/// Iced tries to avoid dictating how to write your event loop. You are in
/// charge of using this type in your system in any way you want.
///
/// # Example
/// The [`integration`] example uses a [`UserInterface`] to integrate Iced in an
/// existing graphical application.
///
/// [`integration`]: https://github.com/iced-rs/iced/tree/0.13/examples/integration
#[allow(missing_debug_implementations)]
pub struct UserInterface<'a, Message, Theme, Renderer> {
root: Element<'a, Message, Theme, Renderer>,
base: layout::Node,
state: widget::Tree,
overlay: Option<layout::Node>,
bounds: Size,
}
impl<'a, Message, Theme, Renderer> UserInterface<'a, Message, Theme, Renderer>
where
Renderer: crate::core::Renderer,
{
/// Builds a user interface for an [`Element`].
///
/// It is able to avoid expensive computations when using a [`Cache`]
/// obtained from a previous instance of a [`UserInterface`].
///
/// # Example
/// Imagine we want to build a [`UserInterface`] for
/// [the counter example that we previously wrote](index.html#usage). Here
/// is naive way to set up our application loop:
///
/// ```no_run
/// # mod iced_wgpu {
/// # pub type Renderer = ();
/// # }
/// #
/// # pub struct Counter;
/// #
/// # impl Counter {
/// # pub fn new() -> Self { Counter }
/// # pub fn view(&self) -> iced_core::Element<(), (), Renderer> { unimplemented!() }
/// # pub fn update(&mut self, _: ()) {}
/// # }
/// use iced_runtime::core::Size;
/// use iced_runtime::user_interface::{self, UserInterface};
/// use iced_wgpu::Renderer;
///
/// // Initialization
/// let mut counter = Counter::new();
/// let mut cache = user_interface::Cache::new();
/// let mut renderer = Renderer::default();
/// let mut window_size = Size::new(1024.0, 768.0);
///
/// // Application loop
/// loop {
/// // Process system events here...
///
/// // Build the user interface
/// let user_interface = UserInterface::build(
/// counter.view(),
/// window_size,
/// cache,
/// &mut renderer,
/// );
///
/// // Update and draw the user interface here...
/// // ...
///
/// // Obtain the cache for the next iteration
/// cache = user_interface.into_cache();
/// }
/// ```
pub fn build<E: Into<Element<'a, Message, Theme, Renderer>>>(
root: E,
bounds: Size,
cache: Cache,
renderer: &mut Renderer,
) -> Self {
let mut root = root.into();
let Cache { mut state } = cache;
NAMED.with(|named| {
let mut guard = named.borrow_mut();
*guard = state.take_all_named();
});
state.diff(root.as_widget_mut());
let base = root.as_widget().layout(
&mut state,
renderer,
&layout::Limits::new(Size::ZERO, bounds),
);
NAMED.with(|named| {
named.borrow_mut().clear();
});
UserInterface {
root,
base,
state,
overlay: None,
bounds,
}
}
/// Updates the [`UserInterface`] by processing each provided [`Event`].
///
/// It returns __messages__ that may have been produced as a result of user
/// interactions. You should feed these to your __update logic__.
///
/// # Example
/// Let's allow our [counter](index.html#usage) to change state by
/// completing [the previous example](#example):
///
/// ```no_run
/// # mod iced_wgpu {
/// # pub type Renderer = ();
/// # }
/// #
/// # pub struct Counter;
/// #
/// # impl Counter {
/// # pub fn new() -> Self { Counter }
/// # pub fn view(&self) -> iced_core::Element<(), (), Renderer> { unimplemented!() }
/// # pub fn update(&mut self, _: ()) {}
/// # }
/// use iced_runtime::core::clipboard;
/// use iced_runtime::core::mouse;
/// use iced_runtime::core::Size;
/// use iced_runtime::user_interface::{self, UserInterface};
/// use iced_wgpu::Renderer;
///
/// let mut counter = Counter::new();
/// let mut cache = user_interface::Cache::new();
/// let mut renderer = Renderer::default();
/// let mut window_size = Size::new(1024.0, 768.0);
/// let mut cursor = mouse::Cursor::default();
/// let mut clipboard = clipboard::Null;
///
/// // Initialize our event storage
/// let mut events = Vec::new();
/// let mut messages = Vec::new();
///
/// loop {
/// // Obtain system events...
///
/// let mut user_interface = UserInterface::build(
/// counter.view(),
/// window_size,
/// cache,
/// &mut renderer,
/// );
///
/// // Update the user interface
/// let (state, event_statuses) = user_interface.update(
/// &events,
/// cursor,
/// &mut renderer,
/// &mut clipboard,
/// &mut messages
/// );
///
/// cache = user_interface.into_cache();
///
/// // Process the produced messages
/// for message in messages.drain(..) {
/// counter.update(message);
/// }
/// }
/// ```
pub fn update(
&mut self,
events: &[Event],
cursor: mouse::Cursor,
renderer: &mut Renderer,
clipboard: &mut dyn Clipboard,
messages: &mut Vec<Message>,
) -> (State, Vec<event::Status>) {
use std::mem::ManuallyDrop;
let mut outdated = false;
let mut redraw_request = None;
let mut manual_overlay = ManuallyDrop::new(
self.root
.as_widget_mut()
.overlay(
&mut self.state,
Layout::new(&self.base),
renderer,
Vector::ZERO,
)
.map(overlay::Nested::new),
);
let (base_cursor, overlay_statuses) = if manual_overlay.is_some() {
let bounds = self.bounds;
let mut overlay = manual_overlay.as_mut().unwrap();
let mut layout = overlay.layout(renderer, bounds);
let mut event_statuses = Vec::new();
for event in events.iter().cloned() {
let mut shell = Shell::new(messages);
let event_status = overlay.on_event(
event,
Layout::new(&layout),
cursor,
renderer,
clipboard,
&mut shell,
);
event_statuses.push(event_status);
match (redraw_request, shell.redraw_request()) {
(None, Some(at)) => {
redraw_request = Some(at);
}
(Some(current), Some(new)) if new < current => {
redraw_request = Some(new);
}
_ => {}
}
if shell.is_layout_invalid() {
let _ = ManuallyDrop::into_inner(manual_overlay);
self.base = self.root.as_widget().layout(
&mut self.state,
renderer,
&layout::Limits::new(Size::ZERO, self.bounds),
);
manual_overlay = ManuallyDrop::new(
self.root
.as_widget_mut()
.overlay(
&mut self.state,
Layout::new(&self.base),
renderer,
Vector::ZERO,
)
.map(overlay::Nested::new),
);
if manual_overlay.is_none() {
break;
}
overlay = manual_overlay.as_mut().unwrap();
shell.revalidate_layout(|| {
layout = overlay.layout(renderer, bounds);
});
}
if shell.are_widgets_invalid() {
outdated = true;
}
}
let base_cursor = if manual_overlay
.as_mut()
.and_then(|overlay| {
cursor.position().map(|cursor_position| {
overlay.is_over(
Layout::new(&layout),
renderer,
cursor_position,
)
})
})
.unwrap_or_default()
{
mouse::Cursor::Unavailable
} else {
cursor
};
self.overlay = Some(layout);
(base_cursor, event_statuses)
} else {
(cursor, vec![event::Status::Ignored; events.len()])
};
let viewport = Rectangle::with_size(self.bounds);
let _ = ManuallyDrop::into_inner(manual_overlay);
let event_statuses = events
.iter()
.cloned()
.zip(overlay_statuses)
.map(|(event, overlay_status)| {
if matches!(overlay_status, event::Status::Captured) {
return overlay_status;
}
let mut shell = Shell::new(messages);
let event_status = self.root.as_widget_mut().on_event(
&mut self.state,
event,
Layout::new(&self.base),
base_cursor,
renderer,
clipboard,
&mut shell,
&viewport,
);
if matches!(event_status, event::Status::Captured) {
self.overlay = None;
}
match (redraw_request, shell.redraw_request()) {
(None, Some(at)) => {
redraw_request = Some(at);
}
(Some(current), Some(new)) if new < current => {
redraw_request = Some(new);
}
_ => {}
}
shell.revalidate_layout(|| {
self.base = self.root.as_widget().layout(
&mut self.state,
renderer,
&layout::Limits::new(Size::ZERO, self.bounds),
);
self.overlay = None;
});
if shell.are_widgets_invalid() {
outdated = true;
}
event_status.merge(overlay_status)
})
.collect();
(
if outdated {
State::Outdated
} else {
State::Updated { redraw_request }
},
event_statuses,
)
}
/// Draws the [`UserInterface`] with the provided [`Renderer`].
///
/// It returns the current [`mouse::Interaction`]. You should update the
/// icon of the mouse cursor accordingly in your system.
///
/// [`Renderer`]: crate::core::Renderer
///
/// # Example
/// We can finally draw our [counter](index.html#usage) by
/// [completing the last example](#example-1):
///
/// ```no_run
/// # mod iced_wgpu {
/// # pub type Renderer = ();
/// # pub type Theme = ();
/// # }
/// #
/// # pub struct Counter;
/// #
/// # impl Counter {
/// # pub fn new() -> Self { Counter }
/// # pub fn view(&self) -> Element<(), (), Renderer> { unimplemented!() }
/// # pub fn update(&mut self, _: ()) {}
/// # }
/// use iced_runtime::core::clipboard;
/// use iced_runtime::core::mouse;
/// use iced_runtime::core::renderer;
/// use iced_runtime::core::{Element, Size};
/// use iced_runtime::user_interface::{self, UserInterface};
/// use iced_wgpu::{Renderer, Theme};
///
/// let mut counter = Counter::new();
/// let mut cache = user_interface::Cache::new();
/// let mut renderer = Renderer::default();
/// let mut window_size = Size::new(1024.0, 768.0);
/// let mut cursor = mouse::Cursor::default();
/// let mut clipboard = clipboard::Null;
/// let mut events = Vec::new();
/// let mut messages = Vec::new();
/// let mut theme = Theme::default();
///
/// loop {
/// // Obtain system events...
///
/// let mut user_interface = UserInterface::build(
/// counter.view(),
/// window_size,
/// cache,
/// &mut renderer,
/// );
///
/// // Update the user interface
/// let event_statuses = user_interface.update(
/// &events,
/// cursor,
/// &mut renderer,
/// &mut clipboard,
/// &mut messages
/// );
///
/// // Draw the user interface
/// let mouse_interaction = user_interface.draw(&mut renderer, &theme, &renderer::Style::default(), cursor);
///
/// cache = user_interface.into_cache();
///
/// for message in messages.drain(..) {
/// counter.update(message);
/// }
///
/// // Update mouse cursor icon...
/// // Flush rendering operations...
/// }
/// ```
pub fn draw(
&mut self,
renderer: &mut Renderer,
theme: &Theme,
style: &renderer::Style,
cursor: mouse::Cursor,
) -> mouse::Interaction {
// TODO: Move to shell level (?)
renderer.clear();
let viewport = Rectangle::with_size(self.bounds);
let base_cursor = if let Some(mut overlay) = self
.root
.as_widget_mut()
.overlay(
&mut self.state,
Layout::new(&self.base),
renderer,
Vector::ZERO,
)
.map(overlay::Nested::new)
{
let overlay_layout = self
.overlay
.take()
.unwrap_or_else(|| overlay.layout(renderer, self.bounds));
let cursor = if cursor
.position()
.map(|cursor_position| {
overlay.is_over(
Layout::new(&overlay_layout),
renderer,
cursor_position,
)
})
.unwrap_or_default()
{
mouse::Cursor::Unavailable
} else {
cursor
};
self.overlay = Some(overlay_layout);
cursor
} else {
cursor
};
self.root.as_widget().draw(
&self.state,
renderer,
theme,
style,
Layout::new(&self.base),
base_cursor,
&viewport,
);
let base_interaction = self.root.as_widget().mouse_interaction(
&self.state,
Layout::new(&self.base),
base_cursor,
&viewport,
renderer,
);
let Self {
overlay,
root,
base,
..
} = self;
// TODO: Currently, we need to call Widget::overlay twice to
// implement the painter's algorithm properly.
//
// Once we have a proper persistent widget tree, we should be able to
// avoid this additional call.
overlay
.as_ref()
.and_then(|layout| {
root.as_widget_mut()
.overlay(
&mut self.state,
Layout::new(base),
renderer,
Vector::ZERO,
)
.map(overlay::Nested::new)
.map(|mut overlay| {
let overlay_interaction = overlay.mouse_interaction(
Layout::new(layout),
cursor,
&viewport,
renderer,
);
overlay.draw(
renderer,
theme,
style,
Layout::new(layout),
cursor,
);
if cursor
.position()
.map(|cursor_position| {
overlay.is_over(
Layout::new(layout),
renderer,
cursor_position,
)
})
.unwrap_or_default()
{
overlay_interaction
} else {
base_interaction
}
})
})
.unwrap_or(base_interaction)
}
/// Applies a [`widget::Operation`] to the [`UserInterface`].
pub fn operate(
&mut self,
renderer: &Renderer,
operation: &mut dyn widget::Operation,
) {
self.root.as_widget().operate(
&mut self.state,
Layout::new(&self.base),
renderer,
operation,
);
if let Some(mut overlay) = self
.root
.as_widget_mut()
.overlay(
&mut self.state,
Layout::new(&self.base),
renderer,
Vector::ZERO,
)
.map(overlay::Nested::new)
{
if self.overlay.is_none() {
self.overlay = Some(overlay.layout(renderer, self.bounds));
}
overlay.operate(
Layout::new(self.overlay.as_ref().unwrap()),
renderer,
operation,
);
}
}
/// Relayouts and returns a new [`UserInterface`] using the provided
/// bounds.
pub fn relayout(self, bounds: Size, renderer: &mut Renderer) -> Self {
Self::build(self.root, bounds, Cache { state: self.state }, renderer)
}
/// Extract the [`Cache`] of the [`UserInterface`], consuming it in the
/// process.
pub fn into_cache(self) -> Cache {
Cache { state: self.state }
}
/// get a11y nodes
#[cfg(feature = "a11y")]
pub fn a11y_nodes(
&self,
cursor: mouse::Cursor,
) -> iced_accessibility::A11yTree {
self.root.as_widget().a11y_nodes(
Layout::new(&self.base),
&self.state,
cursor,
)
}
/// Find widget with given id
pub fn find(&self, id: &widget::Id) -> Option<&widget::Tree> {
self.state.find(id)
}
/// Get the destination rectangles for the user interface.
pub fn dnd_rectangles(
&self,
prev_capacity: usize,
renderer: &Renderer,
) -> DndDestinationRectangles {
let mut ret = DndDestinationRectangles::with_capacity(prev_capacity);
self.root.as_widget().drag_destinations(
&self.state,
Layout::new(&self.base),
renderer,
&mut ret,
);
ret
}
}
/// Reusable data of a specific [`UserInterface`].
#[derive(Debug)]
pub struct Cache {
state: widget::Tree,
}
impl Cache {
/// Creates an empty [`Cache`].
///
/// You should use this to initialize a [`Cache`] before building your first
/// [`UserInterface`].
pub fn new() -> Cache {
Cache {
state: widget::Tree::empty(),
}
}
}
impl Default for Cache {
fn default() -> Cache {
Cache::new()
}
}
/// The resulting state after updating a [`UserInterface`].
#[derive(Debug, Clone, Copy)]
pub enum State {
/// The [`UserInterface`] is outdated and needs to be rebuilt.
Outdated,
/// The [`UserInterface`] is up-to-date and can be reused without
/// rebuilding.
Updated {
/// The [`window::RedrawRequest`] when a redraw should be performed.
redraw_request: Option<window::RedrawRequest>,
},
}