323 lines
9 KiB
Rust
323 lines
9 KiB
Rust
use crate::{input::mouse, Column, Element, Event, Layout, MouseCursor, Point};
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use std::hash::Hasher;
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use stretch::result;
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/// A set of interactive graphical elements with a specific [`Layout`].
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///
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/// It can be updated and drawn.
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///
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/// Iced tries to avoid dictating how to write your event loop. You are in
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/// charge of using this type in your system in any way you want.
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///
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/// [`Layout`]: struct.Layout.html
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#[derive(Debug)]
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pub struct UserInterface<'a, Message, Renderer> {
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hash: u64,
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root: Element<'a, Message, Renderer>,
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layout: result::Layout,
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cursor_position: Point,
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}
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impl<'a, Message, Renderer> UserInterface<'a, Message, Renderer> {
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/// Builds a user interface for an [`Element`].
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///
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/// It is able to avoid expensive computations when using a [`Cache`]
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/// obtained from a previous instance of a [`UserInterface`].
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///
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/// [`Element`]: struct.Element.html
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/// [`Cache`]: struct.Cache.html
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/// [`UserInterface`]: struct.UserInterface.html
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///
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/// # Example
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/// Imagine we want to build a [`UserInterface`] for
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/// [the counter example that we previously wrote](index.html#usage). Here
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/// is naive way to set up our application loop:
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///
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/// ```no_run
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/// use iced::{UserInterface, Cache};
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/// use iced_wgpu::Renderer;
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///
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/// # mod iced_wgpu {
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/// # pub struct Renderer;
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/// #
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/// # impl Renderer {
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/// # pub fn new() -> Self { Renderer }
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/// # }
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/// # }
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/// #
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/// # use iced::Column;
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/// #
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/// # pub struct Counter;
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/// #
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/// # impl Counter {
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/// # pub fn new() -> Self { Counter }
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/// # pub fn view(&self) -> Column<(), Renderer> {
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/// # Column::new()
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/// # }
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/// # }
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/// // Initialization
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/// let mut counter = Counter::new();
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/// let mut cache = Cache::new();
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/// let mut renderer = Renderer::new();
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///
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/// // Application loop
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/// loop {
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/// // Process system events here...
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///
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/// // Build the user interface
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/// let user_interface = UserInterface::build(
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/// counter.view(),
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/// cache,
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/// &mut renderer,
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/// );
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///
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/// // Update and draw the user interface here...
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/// // ...
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///
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/// // Obtain the cache for the next iteration
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/// cache = user_interface.into_cache();
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/// }
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/// ```
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pub fn build<E: Into<Element<'a, Message, Renderer>>>(
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root: E,
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cache: Cache,
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renderer: &mut Renderer,
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) -> Self {
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let root = root.into();
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let hasher = &mut crate::Hasher::default();
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root.hash_layout(hasher);
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let hash = hasher.finish();
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let layout = if hash == cache.hash {
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cache.layout
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} else {
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root.compute_layout(renderer)
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};
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UserInterface {
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hash,
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root,
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layout,
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cursor_position: cache.cursor_position,
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}
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}
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/// Updates the [`UserInterface`] by processing each provided [`Event`].
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///
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/// It returns __messages__ that may have been produced as a result of user
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/// interactions. You should feed these to your __update logic__.
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///
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/// [`UserInterface`]: struct.UserInterface.html
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/// [`Event`]: enum.Event.html
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///
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/// # Example
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/// Let's allow our [counter](index.html#usage) to change state by completing
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/// [the previous example](#example):
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///
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/// ```no_run
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/// use iced::{UserInterface, Cache};
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/// use iced_wgpu::Renderer;
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///
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/// # mod iced_wgpu {
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/// # pub struct Renderer;
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/// #
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/// # impl Renderer {
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/// # pub fn new() -> Self { Renderer }
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/// # }
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/// # }
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/// #
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/// # use iced::Column;
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/// #
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/// # pub struct Counter;
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/// #
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/// # impl Counter {
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/// # pub fn new() -> Self { Counter }
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/// # pub fn view(&self) -> Column<(), Renderer> {
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/// # Column::new()
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/// # }
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/// # pub fn update(&mut self, message: ()) {}
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/// # }
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/// let mut counter = Counter::new();
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/// let mut cache = Cache::new();
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/// let mut renderer = Renderer::new();
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///
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/// // Initialize our event storage
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/// let mut events = Vec::new();
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///
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/// loop {
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/// // Process system events...
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///
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/// let mut user_interface = UserInterface::build(
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/// counter.view(),
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/// cache,
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/// &mut renderer,
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/// );
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///
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/// // Update the user interface
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/// let messages = user_interface.update(events.drain(..));
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///
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/// cache = user_interface.into_cache();
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///
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/// // Process the produced messages
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/// for message in messages {
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/// counter.update(message);
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/// }
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/// }
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/// ```
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pub fn update(
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&mut self,
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events: impl Iterator<Item = Event>,
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) -> Vec<Message> {
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let mut messages = Vec::new();
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for event in events {
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if let Event::Mouse(mouse::Event::CursorMoved { x, y }) = event {
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self.cursor_position = Point::new(x, y);
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}
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self.root.widget.on_event(
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event,
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Layout::new(&self.layout),
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self.cursor_position,
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&mut messages,
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);
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}
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messages
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}
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/// Draws the [`UserInterface`] with the provided [`Renderer`].
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///
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/// It returns the current state of the [`MouseCursor`]. You should update
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/// the icon of the mouse cursor accordingly in your system.
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///
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/// [`UserInterface`]: struct.UserInterface.html
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/// [`Renderer`]: trait.Renderer.html
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/// [`MouseCursor`]: enum.MouseCursor.html
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///
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/// # Example
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/// We can finally draw our [counter](index.html#usage) by
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/// [completing the last example](#example-1):
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///
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/// ```no_run
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/// use iced::{UserInterface, Cache};
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/// use iced_wgpu::Renderer;
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///
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/// # mod iced_wgpu {
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/// # pub struct Renderer;
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/// #
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/// # impl Renderer {
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/// # pub fn new() -> Self { Renderer }
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/// # }
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/// # }
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/// #
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/// # use iced::Column;
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/// #
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/// # pub struct Counter;
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/// #
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/// # impl Counter {
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/// # pub fn new() -> Self { Counter }
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/// # pub fn view(&self) -> Column<(), Renderer> {
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/// # Column::new()
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/// # }
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/// # pub fn update(&mut self, message: ()) {}
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/// # }
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/// let mut counter = Counter::new();
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/// let mut cache = Cache::new();
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/// let mut renderer = Renderer::new();
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/// let mut events = Vec::new();
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///
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/// loop {
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/// // Process system events...
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///
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/// let mut user_interface = UserInterface::build(
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/// counter.view(),
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/// cache,
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/// &mut renderer,
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/// );
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///
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/// let messages = user_interface.update(events.drain(..));
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///
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/// // Draw the user interface
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/// let mouse_cursor = user_interface.draw(&mut renderer);
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///
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/// cache = user_interface.into_cache();
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///
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/// for message in messages {
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/// counter.update(message);
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/// }
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///
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/// // Update mouse cursor icon...
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/// // Flush rendering operations...
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/// }
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/// ```
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pub fn draw(&self, renderer: &mut Renderer) -> MouseCursor {
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self.root.widget.draw(
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renderer,
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Layout::new(&self.layout),
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self.cursor_position,
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)
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}
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/// Extract the [`Cache`] of the [`UserInterface`], consuming it in the
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/// process.
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///
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/// [`Cache`]: struct.Cache.html
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/// [`UserInterface`]: struct.UserInterface.html
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pub fn into_cache(self) -> Cache {
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Cache {
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hash: self.hash,
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layout: self.layout,
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cursor_position: self.cursor_position,
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}
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}
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}
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/// Reusable data of a specific [`UserInterface`].
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///
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/// [`UserInterface`]: struct.UserInterface.html
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#[derive(Debug, Clone)]
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pub struct Cache {
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hash: u64,
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layout: result::Layout,
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cursor_position: Point,
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}
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impl Cache {
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/// Creates an empty [`Cache`].
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///
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/// You should use this to initialize a [`Cache`] before building your first
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/// [`UserInterface`].
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///
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/// [`Cache`]: struct.Cache.html
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/// [`UserInterface`]: struct.UserInterface.html
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pub fn new() -> Cache {
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let root: Element<'_, (), ()> = Column::new().into();
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let hasher = &mut crate::Hasher::default();
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root.hash_layout(hasher);
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Cache {
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hash: hasher.finish(),
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layout: root.compute_layout(&mut ()),
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cursor_position: Point::new(0.0, 0.0),
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}
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}
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}
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impl Default for Cache {
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fn default() -> Cache {
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Cache::new()
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}
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}
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impl PartialEq for Cache {
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fn eq(&self, other: &Cache) -> bool {
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self.hash == other.hash && self.cursor_position == other.cursor_position
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}
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}
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impl Eq for Cache {}
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