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helix/helix-term/src/compositor.rs

228 lines
6.7 KiB
Rust

4 years ago
// Each component declares it's own size constraints and gets fitted based on it's parent.
// Q: how does this work with popups?
// cursive does compositor.screen_mut().add_layer_at(pos::absolute(x, y), <component>)
use crossterm::event::Event;
use helix_core::Position;
use tui::{buffer::Buffer as Surface, layout::Rect};
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pub type Callback = Box<dyn FnOnce(&mut Compositor, &mut Editor)>;
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// --> EventResult should have a callback that takes a context with methods like .popup(),
// .prompt() etc. That way we can abstract it from the renderer.
// Q: How does this interact with popups where we need to be able to specify the rendering of the
// popup?
// A: It could just take a textarea.
//
// If Compositor was specified in the callback that's then problematic because of
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// Cursive-inspired
pub enum EventResult {
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Ignored,
Consumed(Option<Callback>),
}
use helix_view::{Editor, View};
use crate::application::LspCallbacks;
pub struct Context<'a> {
pub editor: &'a mut Editor,
pub scroll: Option<usize>,
pub callbacks: &'a mut LspCallbacks,
}
pub trait Component: Any + AnyComponent {
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/// Process input events, return true if handled.
fn handle_event(&mut self, event: Event, ctx: &mut Context) -> EventResult {
EventResult::Ignored
}
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// , args: ()
/// Should redraw? Useful for saving redraw cycles if we know component didn't change.
fn should_update(&self) -> bool {
true
}
/// Render the component onto the provided surface.
fn render(&self, area: Rect, frame: &mut Surface, ctx: &mut Context);
fn cursor_position(&self, area: Rect, ctx: &Editor) -> Option<Position> {
None
}
/// May be used by the parent component to compute the child area.
/// viewport is the maximum allowed area, and the child should stay within those bounds.
fn required_size(&mut self, viewport: (u16, u16)) -> Option<(u16, u16)> {
// TODO: for scrolling, the scroll wrapper should place a size + offset on the Context
// that way render can use it
None
}
fn type_name(&self) -> &'static str {
std::any::type_name::<Self>()
}
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}
use anyhow::Error;
use std::io::stdout;
use tui::backend::CrosstermBackend;
type Terminal = tui::terminal::Terminal<CrosstermBackend<std::io::Stdout>>;
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pub struct Compositor {
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layers: Vec<Box<dyn Component>>,
terminal: Terminal,
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}
impl Compositor {
pub fn new() -> Result<Self, Error> {
let backend = CrosstermBackend::new(stdout());
let mut terminal = Terminal::new(backend)?;
Ok(Self {
layers: Vec::new(),
terminal,
})
}
pub fn size(&self) -> Rect {
self.terminal.size().expect("couldn't get terminal size")
}
pub fn resize(&mut self, width: u16, height: u16) {
self.terminal
.resize(Rect::new(0, 0, width, height))
.expect("Unable to resize terminal")
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}
pub fn push(&mut self, mut layer: Box<dyn Component>) {
let size = self.size();
// trigger required_size on init
layer.required_size((size.width, size.height));
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self.layers.push(layer);
}
pub fn pop(&mut self) {
self.layers.pop();
}
pub fn handle_event(&mut self, event: Event, cx: &mut Context) -> bool {
// propagate events through the layers until we either find a layer that consumes it or we
// run out of layers (event bubbling)
for layer in self.layers.iter_mut().rev() {
match layer.handle_event(event, cx) {
EventResult::Consumed(Some(callback)) => {
callback(self, cx.editor);
return true;
}
EventResult::Consumed(None) => return true,
EventResult::Ignored => false,
};
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}
false
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}
pub fn render(&mut self, cx: &mut Context) {
let area = self.size();
let surface = self.terminal.current_buffer_mut();
for layer in &self.layers {
layer.render(area, surface, cx)
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}
let pos = self
.cursor_position(area, cx.editor)
.map(|pos| (pos.col as u16, pos.row as u16));
self.terminal.draw(pos);
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}
pub fn cursor_position(&self, area: Rect, editor: &Editor) -> Option<Position> {
for layer in self.layers.iter().rev() {
if let Some(pos) = layer.cursor_position(area, editor) {
return Some(pos);
}
}
None
}
pub fn find(&mut self, type_name: &str) -> Option<&mut dyn Component> {
self.layers
.iter_mut()
.find(|component| component.type_name() == type_name)
.map(|component| component.as_mut())
}
}
// View casting, taken straight from Cursive
use std::any::Any;
/// A view that can be downcasted to its concrete type.
///
/// This trait is automatically implemented for any `T: Component`.
pub trait AnyComponent {
/// Downcast self to a `Any`.
fn as_any(&self) -> &dyn Any;
/// Downcast self to a mutable `Any`.
fn as_any_mut(&mut self) -> &mut dyn Any;
/// Returns a boxed any from a boxed self.
///
/// Can be used before `Box::downcast()`.
///
/// # Examples
///
/// ```rust
/// # use cursive_core::views::TextComponent;
/// # use cursive_core::view::Component;
/// let boxed: Box<Component> = Box::new(TextComponent::new("text"));
/// let text: Box<TextComponent> = boxed.as_boxed_any().downcast().unwrap();
/// ```
fn as_boxed_any(self: Box<Self>) -> Box<dyn Any>;
}
impl<T: Component> AnyComponent for T {
/// Downcast self to a `Any`.
fn as_any(&self) -> &dyn Any {
self
}
/// Downcast self to a mutable `Any`.
fn as_any_mut(&mut self) -> &mut dyn Any {
self
}
fn as_boxed_any(self: Box<Self>) -> Box<dyn Any> {
self
}
}
impl dyn AnyComponent {
/// Attempts to downcast `self` to a concrete type.
pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
self.as_any().downcast_ref()
}
/// Attempts to downcast `self` to a concrete type.
pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
self.as_any_mut().downcast_mut()
}
/// Attempts to downcast `Box<Self>` to a concrete type.
pub fn downcast<T: Any>(self: Box<Self>) -> Result<Box<T>, Box<Self>> {
// Do the check here + unwrap, so the error
// value is `Self` and not `dyn Any`.
if self.as_any().is::<T>() {
Ok(self.as_boxed_any().downcast().unwrap())
} else {
Err(self)
}
}
/// Checks if this view is of type `T`.
pub fn is<T: Any>(&mut self) -> bool {
self.as_any().is::<T>()
}
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}