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use std::io;
use std::collections::HashMap;
use backend::Backend;
use buffer::Buffer;
use layout::{Rect, Group, split};
use widgets::Widget;
/// Holds a computed layout and keeps track of its use between successive draw calls
#[derive(Debug)]
pub struct LayoutEntry {
chunks: Vec<Rect>,
hot: bool,
}
/// Interface to the terminal backed by Termion
pub struct Terminal<B>
where B: Backend
{
backend: B,
/// Cache to prevent the layout to be computed at each draw call
layout_cache: HashMap<(Group, Rect), LayoutEntry>,
/// Holds the results of the current and previous draw calls. The two are compared at the end
/// of each draw pass to output the necessary updates to the terminal
buffers: [Buffer; 2],
/// Index of the current buffer in the previous array
current: usize,
}
impl<B> Terminal<B>
where B: Backend
{
/// Wrapper around Termion initialization. Each buffer is initialized with a blank string and
/// default colors for the foreground and the background
pub fn new(backend: B) -> Result<Terminal<B>, io::Error> {
let size = try!(backend.size());
Ok(Terminal {
backend: backend,
layout_cache: HashMap::new(),
buffers: [Buffer::empty(size), Buffer::empty(size)],
current: 0,
})
}
pub fn backend(&self) -> &B {
&self.backend
}
pub fn backend_mut(&mut self) -> &mut B {
&mut self.backend
}
/// Check if we have already computed a layout for a given group, otherwise it creates one and
/// add it to the layout cache. Moreover the function marks the queried entries so that we can
/// clean outdated ones at the end of the draw call.
pub fn compute_layout(&mut self, group: &Group, area: &Rect) -> Vec<Rect> {
let entry = self.layout_cache
.entry((group.clone(), *area))
.or_insert_with(|| {
let chunks = split(area, &group.direction, group.margin, &group.sizes);
debug!("New layout computed:\n* Group = {:?}\n* Chunks = {:?}",
group,
chunks);
LayoutEntry {
chunks: chunks,
hot: true,
}
});
entry.hot = true;
entry.chunks.clone()
}
/// Builds a string representing the minimal escape sequences and characters set necessary to
/// update the UI and writes it to stdout.
pub fn flush(&mut self) -> Result<(), io::Error> {
let width = self.buffers[self.current].area.width;
let content = self.buffers[self.current]
.content
.iter()
.zip(self.buffers[1 - self.current].content.iter())
.enumerate()
.filter_map(|(i, (c, p))| if c != p {
let i = i as u16;
let x = i % width;
let y = i / width;
Some((x, y, c))
} else {
None
});
self.backend.draw(content)
}
/// Calls the draw method of a given widget on the current buffer
pub fn render<W>(&mut self, widget: &W, area: &Rect)
where W: Widget
{
widget.draw(area, &mut self.buffers[self.current]);
}
/// Updates the interface so that internal buffers matches the current size of the terminal.
/// This leads to a full redraw of the screen.
pub fn resize(&mut self, area: Rect) -> Result<(), io::Error> {
self.buffers[self.current].resize(area);
self.buffers[1 - self.current].resize(area);
self.buffers[1 - self.current].reset();
self.layout_cache.clear();
self.backend.clear()
}
/// Flushes the current internal state and prepares the interface for the next draw call
pub fn draw(&mut self) -> Result<(), io::Error> {
// Draw to stdout
self.flush()?;
// Clean layout cache
let hot = self.layout_cache
.drain()
.filter(|&(_, ref v)| v.hot)
.collect::<Vec<((Group, Rect), LayoutEntry)>>();
for (key, value) in hot {
self.layout_cache.insert(key, value);
}
for e in self.layout_cache.values_mut() {
e.hot = false;
}
// Swap buffers
self.buffers[1 - self.current].reset();
self.current = 1 - self.current;
// Flush
self.backend.flush()?;
Ok(())
}
pub fn hide_cursor(&mut self) -> Result<(), io::Error> {
self.backend.hide_cursor()
}
pub fn show_cursor(&mut self) -> Result<(), io::Error> {
self.backend.show_cursor()
}
pub fn clear(&mut self) -> Result<(), io::Error> {
self.backend.clear()
}
pub fn size(&self) -> Result<Rect, io::Error> {
self.backend.size()
}
}