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// 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 smol::Executor;
use tui::buffer::Buffer as Surface;
use tui::layout::Rect;
pub type Callback = Box<dyn FnOnce(&mut Compositor, &mut Editor)>;
// --> 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
// Cursive-inspired
pub enum EventResult {
Ignored,
Consumed(Option<Callback>),
}
use helix_view::{Editor, View};
pub struct Context<'a> {
pub editor: &'a mut Editor,
pub executor: &'static smol::Executor<'static>,
pub scroll: Option<usize>,
}
pub trait Component {
/// Process input events, return true if handled.
fn handle_event(&mut self, event: Event, ctx: &mut Context) -> EventResult {
EventResult::Ignored
}
// , 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: the compositor should trigger this on push_layer too so that we can use it as an
// initializer there too.
//
// TODO: for scrolling, the scroll wrapper should place a size + offset on the Context
// that way render can use it
None
}
}
use anyhow::Error;
use std::io::stdout;
use tui::backend::CrosstermBackend;
type Terminal = crate::terminal::Terminal<CrosstermBackend<std::io::Stdout>>;
pub struct Compositor {
layers: Vec<Box<dyn Component>>,
terminal: Terminal,
}
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")
}
pub fn push(&mut self, layer: Box<dyn Component>) {
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,
};
}
false
}
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)
}
let pos = self
.cursor_position(area, cx.editor)
.map(|pos| (pos.col as u16, pos.row as u16));
self.terminal.draw(pos);
}
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
}
}
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