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440 lines
13 KiB
Rust
440 lines
13 KiB
Rust
use crate::{
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backend::Backend,
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buffer::Buffer,
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layout::Rect,
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widgets::{RenderContext, Widget},
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};
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use std::{any::Any, collections::HashMap, hash::Hash, io, panic::Location};
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#[derive(Debug, Clone, PartialEq)]
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/// UNSTABLE
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enum ResizeBehavior {
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Fixed,
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Auto,
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}
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#[derive(Debug, Clone, PartialEq)]
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/// UNSTABLE
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pub struct Viewport {
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area: Rect,
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resize_behavior: ResizeBehavior,
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}
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impl Viewport {
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/// UNSTABLE
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pub fn fixed(area: Rect) -> Viewport {
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Viewport {
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area,
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resize_behavior: ResizeBehavior::Fixed,
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}
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}
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}
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#[derive(Clone, Copy, Debug)]
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pub(crate) struct CallLocation(&'static Location<'static>);
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impl CallLocation {
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fn as_ptr(&self) -> *const Location<'static> {
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self.0
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}
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}
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impl Hash for CallLocation {
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fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
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self.as_ptr().hash(state)
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}
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}
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impl PartialEq for CallLocation {
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fn eq(&self, other: &Self) -> bool {
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self.as_ptr() == other.as_ptr()
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}
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}
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impl Eq for CallLocation {}
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/// StateEntry is used to link a [`Frame::render_widget`] to [`Widget::State`].
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#[derive(Debug, Clone, PartialEq, Eq, Hash)]
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struct StateKey {
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/// Location of the call to [`Frame::render_widget`].
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call_location: CallLocation,
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/// Optional id that can be used to have multiple widgets state at the same call location.
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id: Option<String>,
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}
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/// StateEntry holds the state of a [`Widget`].
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struct StateEntry {
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/// State of a [`Widget`].
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state: Box<dyn Any>,
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/// Index of the frame where the state was used for the last time.
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frame_index: usize,
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}
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#[derive(Debug, Clone, PartialEq)]
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/// Options to pass to [`Terminal::with_options`]
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pub struct TerminalOptions {
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/// Viewport used to draw to the terminal
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pub viewport: Viewport,
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}
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/// Interface to the terminal backed by Termion
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pub struct Terminal<B>
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where
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B: Backend,
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{
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backend: B,
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/// Holds the results of the current and previous draw calls. The two are compared at the end
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/// of each draw pass to output the necessary updates to the terminal
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buffers: [Buffer; 2],
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/// Index of the current buffer in the previous array
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current: usize,
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/// Whether the cursor is currently hidden
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hidden_cursor: bool,
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/// Viewport
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viewport: Viewport,
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/// State of the widgets rendered in the previous frame.
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widget_states: HashMap<StateKey, StateEntry>,
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/// Index of the current frame. Incremented each time [`Terminal::draw`] is called and wraps
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/// when it is greater than [`std::usize::MAX`].
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frame_index: usize,
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}
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/// Represents a consistent terminal interface for rendering.
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pub struct Frame<'a, B: 'a>
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where
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B: Backend,
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{
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terminal: &'a mut Terminal<B>,
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/// Where should the cursor be after drawing this frame?
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///
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/// If `None`, the cursor is hidden and its position is controlled by the backend. If `Some((x,
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/// y))`, the cursor is shown and placed at `(x, y)` after the call to `Terminal::draw()`.
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cursor_position: Option<(u16, u16)>,
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}
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/// RenderArgs are the arguments required to render a [`Widget`].
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pub struct RenderArgs {
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/// Area where the widget will be rendered.
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area: Rect,
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/// Optional id that can be used to uniquely identify the provided [`Widget`].
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id: Option<String>,
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}
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impl From<Rect> for RenderArgs {
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fn from(area: Rect) -> RenderArgs {
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RenderArgs { area, id: None }
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}
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}
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impl RenderArgs {
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/// Set the [`Widget`] id.
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pub fn id<S>(mut self, id: S) -> Self
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where
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S: Into<String>,
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{
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self.id = Some(id.into());
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self
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}
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}
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impl<'a, B> Frame<'a, B>
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where
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B: Backend,
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{
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/// Terminal size, guaranteed not to change when rendering.
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pub fn size(&self) -> Rect {
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self.terminal.viewport.area
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}
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/// Render a [`Widget`] to the current buffer using [`Widget::render`].
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///
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/// # Examples
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///
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/// ```rust,no_run
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/// # use std::io;
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/// # use tui::Terminal;
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/// # use tui::backend::TermionBackend;
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/// # use tui::layout::Rect;
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/// # use tui::widgets::Block;
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/// # let stdout = io::stdout();
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/// # let backend = TermionBackend::new(stdout);
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/// # let mut terminal = Terminal::new(backend).unwrap();
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/// let block = Block::default();
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/// let area = Rect::new(0, 0, 5, 5);
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/// let mut frame = terminal.get_frame();
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/// frame.render_widget(block, area);
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/// ```
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///
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/// If you happen to render two or more widgets using the same render call, you may want to
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/// associate them with a unique id so they do not share any internal state.
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///
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/// For example, let say your app shows a list of songs of a given album:
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/// ```rust,no_run
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/// # use std::{collections::HashMap, io};
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/// # use tui::{Terminal, RenderArgs};
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/// # use tui::backend::TermionBackend;
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/// # use tui::layout::Rect;
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/// # use tui::widgets::{Block, List, ListItem};
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/// # let stdout = io::stdout();
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/// # let backend = TermionBackend::new(stdout);
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/// # let mut terminal = Terminal::new(backend).unwrap();
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/// struct App {
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/// albums: HashMap<String, Vec<String>>,
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/// selected_album: String
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/// }
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/// # let app = App {
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/// # albums: HashMap::new(),
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/// # selected_album: String::new(),
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/// # };
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/// terminal.draw(|f| {
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/// let songs: Vec<ListItem> = app.albums[&app.selected_album]
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/// .iter()
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/// .map(|song| ListItem::new(song.as_ref()))
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/// .collect();
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/// let song_list = List::new(songs)
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/// .block(Block::default().title(app.selected_album.as_ref()));
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/// // Giving a unique id here makes sure the list state is reset whenever the album
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/// // currently displayed changes.
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/// let args = RenderArgs::from(f.size()).id(app.selected_album.clone());
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/// f.render_widget(song_list, args);
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/// });
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/// ```
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#[track_caller]
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pub fn render_widget<W, R>(&mut self, widget: W, args: R)
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where
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W: Widget,
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W::State: 'static + Default,
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R: Into<RenderArgs>,
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{
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// Fetch the previous internal state of the widget (or initialize it with a default value).
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let args: RenderArgs = args.into();
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let location = Location::caller();
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let key = StateKey {
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call_location: CallLocation(location),
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id: args.id,
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};
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let entry = self
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.terminal
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.widget_states
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.entry(key)
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.or_insert_with(|| StateEntry {
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state: Box::new(<W::State>::default()),
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frame_index: 0,
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});
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let state: &mut W::State = entry
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.state
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.downcast_mut()
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.expect("The state associated to a widget is not of an expected type");
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// Update the frame index to communicate that it was used during the current draw call.
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entry.frame_index = self.terminal.frame_index;
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// Render the widget
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let buffer = &mut self.terminal.buffers[self.terminal.current];
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let mut context = RenderContext {
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area: args.area,
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buffer,
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state,
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};
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widget.render(&mut context);
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}
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/// After drawing this frame, make the cursor visible and put it at the specified (x, y)
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/// coordinates. If this method is not called, the cursor will be hidden.
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///
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/// Note that this will interfere with calls to `Terminal::hide_cursor()`,
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/// `Terminal::show_cursor()`, and `Terminal::set_cursor()`. Pick one of the APIs and stick
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/// with it.
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pub fn set_cursor(&mut self, x: u16, y: u16) {
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self.cursor_position = Some((x, y));
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}
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}
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/// CompletedFrame represents the state of the terminal after all changes performed in the last
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/// [`Terminal::draw`] call have been applied. Therefore, it is only valid until the next call to
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/// [`Terminal::draw`].
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pub struct CompletedFrame<'a> {
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pub buffer: &'a Buffer,
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pub area: Rect,
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}
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impl<B> Drop for Terminal<B>
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where
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B: Backend,
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{
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fn drop(&mut self) {
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// Attempt to restore the cursor state
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if self.hidden_cursor {
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if let Err(err) = self.show_cursor() {
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eprintln!("Failed to show the cursor: {}", err);
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}
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}
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}
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}
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impl<B> Terminal<B>
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where
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B: Backend,
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{
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/// Wrapper around Terminal initialization. Each buffer is initialized with a blank string and
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/// default colors for the foreground and the background
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pub fn new(backend: B) -> io::Result<Terminal<B>> {
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let size = backend.size()?;
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Terminal::with_options(
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backend,
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TerminalOptions {
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viewport: Viewport {
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area: size,
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resize_behavior: ResizeBehavior::Auto,
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},
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},
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)
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}
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/// UNSTABLE
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pub fn with_options(backend: B, options: TerminalOptions) -> io::Result<Terminal<B>> {
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Ok(Terminal {
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backend,
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buffers: [
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Buffer::empty(options.viewport.area),
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Buffer::empty(options.viewport.area),
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],
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current: 0,
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hidden_cursor: false,
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viewport: options.viewport,
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widget_states: HashMap::new(),
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frame_index: 0,
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})
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}
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/// Get a Frame object which provides a consistent view into the terminal state for rendering.
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pub fn get_frame(&mut self) -> Frame<B> {
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Frame {
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terminal: self,
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cursor_position: None,
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}
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}
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pub fn current_buffer_mut(&mut self) -> &mut Buffer {
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&mut self.buffers[self.current]
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}
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pub fn backend(&self) -> &B {
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&self.backend
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}
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pub fn backend_mut(&mut self) -> &mut B {
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&mut self.backend
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}
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/// Obtains a difference between the previous and the current buffer and passes it to the
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/// current backend for drawing.
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pub fn flush(&mut self) -> io::Result<()> {
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let previous_buffer = &self.buffers[1 - self.current];
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let current_buffer = &self.buffers[self.current];
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let updates = previous_buffer.diff(current_buffer);
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self.backend.draw(updates.into_iter())
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}
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/// Updates the Terminal so that internal buffers match the requested size. Requested size will
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/// be saved so the size can remain consistent when rendering.
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/// This leads to a full clear of the screen.
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pub fn resize(&mut self, area: Rect) -> io::Result<()> {
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self.buffers[self.current].resize(area);
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self.buffers[1 - self.current].resize(area);
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self.viewport.area = area;
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self.clear()
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}
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/// Queries the backend for size and resizes if it doesn't match the previous size.
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pub fn autoresize(&mut self) -> io::Result<()> {
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if self.viewport.resize_behavior == ResizeBehavior::Auto {
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let size = self.size()?;
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if size != self.viewport.area {
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self.resize(size)?;
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}
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};
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Ok(())
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}
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/// Synchronizes terminal size, calls the rendering closure, flushes the current internal state
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/// and prepares for the next draw call.
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pub fn draw<F>(&mut self, f: F) -> io::Result<CompletedFrame>
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where
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F: FnOnce(&mut Frame<B>),
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{
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// Autoresize - otherwise we get glitches if shrinking or potential desync between widgets
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// and the terminal (if growing), which may OOB.
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self.autoresize()?;
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let mut frame = self.get_frame();
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f(&mut frame);
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// We can't change the cursor position right away because we have to flush the frame to
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// stdout first. But we also can't keep the frame around, since it holds a &mut to
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// Terminal. Thus, we're taking the important data out of the Frame and dropping it.
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let cursor_position = frame.cursor_position;
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// Draw to stdout
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self.flush()?;
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match cursor_position {
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None => self.hide_cursor()?,
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Some((x, y)) => {
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self.show_cursor()?;
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self.set_cursor(x, y)?;
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}
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}
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// Swap buffers
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self.buffers[1 - self.current].reset();
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self.current = 1 - self.current;
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// Clean states that were not used in this frame
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let frame_index = self.frame_index;
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self.widget_states
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.retain(|_, v| v.frame_index == frame_index);
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self.frame_index = self.frame_index.wrapping_add(1);
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// Flush
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self.backend.flush()?;
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Ok(CompletedFrame {
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buffer: &self.buffers[1 - self.current],
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area: self.viewport.area,
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})
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}
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pub fn hide_cursor(&mut self) -> io::Result<()> {
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self.backend.hide_cursor()?;
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self.hidden_cursor = true;
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Ok(())
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}
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pub fn show_cursor(&mut self) -> io::Result<()> {
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self.backend.show_cursor()?;
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self.hidden_cursor = false;
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Ok(())
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}
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pub fn get_cursor(&mut self) -> io::Result<(u16, u16)> {
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self.backend.get_cursor()
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}
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pub fn set_cursor(&mut self, x: u16, y: u16) -> io::Result<()> {
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self.backend.set_cursor(x, y)
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}
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/// Clear the terminal and force a full redraw on the next draw call.
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pub fn clear(&mut self) -> io::Result<()> {
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self.backend.clear()?;
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// Reset the back buffer to make sure the next update will redraw everything.
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self.buffers[1 - self.current].reset();
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Ok(())
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}
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/// Queries the real size of the backend.
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pub fn size(&self) -> io::Result<Rect> {
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self.backend.size()
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}
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}
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