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use std::io;
use tui::{
backend::Backend,
buffer::Buffer,
layout::Rect,
widgets::{StatefulWidget, Widget},
};
#[derive(Debug, Clone, PartialEq)]
/// UNSTABLE
enum ResizeBehavior {
Fixed,
Auto,
}
#[derive(Debug, Clone, PartialEq)]
/// UNSTABLE
pub struct Viewport {
area: Rect,
resize_behavior: ResizeBehavior,
}
impl Viewport {
/// UNSTABLE
pub fn fixed(area: Rect) -> Viewport {
Viewport {
area,
resize_behavior: ResizeBehavior::Fixed,
}
}
}
#[derive(Debug, Clone, PartialEq)]
/// Options to pass to [`Terminal::with_options`]
pub struct TerminalOptions {
/// Viewport used to draw to the terminal
pub viewport: Viewport,
}
/// Interface to the terminal backed by Termion
#[derive(Debug)]
pub struct Terminal<B>
where
B: Backend,
{
backend: B,
/// 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,
/// Whether the cursor is currently hidden
hidden_cursor: bool,
/// Viewport
viewport: Viewport,
}
impl<B> Drop for Terminal<B>
where
B: Backend,
{
fn drop(&mut self) {
// Attempt to restore the cursor state
if self.hidden_cursor {
if let Err(err) = self.show_cursor() {
eprintln!("Failed to show the cursor: {}", err);
}
}
}
}
impl<B> Terminal<B>
where
B: Backend,
{
/// Wrapper around Terminal initialization. Each buffer is initialized with a blank string and
/// default colors for the foreground and the background
pub fn new(backend: B) -> io::Result<Terminal<B>> {
let size = backend.size()?;
Terminal::with_options(
backend,
TerminalOptions {
viewport: Viewport {
area: size,
resize_behavior: ResizeBehavior::Auto,
},
},
)
}
/// UNSTABLE
pub fn with_options(backend: B, options: TerminalOptions) -> io::Result<Terminal<B>> {
Ok(Terminal {
backend,
buffers: [
Buffer::empty(options.viewport.area),
Buffer::empty(options.viewport.area),
],
current: 0,
hidden_cursor: false,
viewport: options.viewport,
})
}
// /// Get a Frame object which provides a consistent view into the terminal state for rendering.
// pub fn get_frame(&mut self) -> Frame<B> {
// Frame {
// terminal: self,
// cursor_position: None,
// }
// }
pub fn current_buffer_mut(&mut self) -> &mut Buffer {
&mut self.buffers[self.current]
}
pub fn backend(&self) -> &B {
&self.backend
}
pub fn backend_mut(&mut self) -> &mut B {
&mut self.backend
}
/// Obtains a difference between the previous and the current buffer and passes it to the
/// current backend for drawing.
pub fn flush(&mut self) -> io::Result<()> {
let previous_buffer = &self.buffers[1 - self.current];
let current_buffer = &self.buffers[self.current];
let updates = previous_buffer.diff(current_buffer);
self.backend.draw(updates.into_iter())
}
/// Updates the Terminal so that internal buffers match the requested size. Requested size will
/// be saved so the size can remain consistent when rendering.
/// This leads to a full clear of the screen.
pub fn resize(&mut self, area: Rect) -> io::Result<()> {
self.buffers[self.current].resize(area);
self.buffers[1 - self.current].resize(area);
self.viewport.area = area;
self.clear()
}
/// Queries the backend for size and resizes if it doesn't match the previous size.
pub fn autoresize(&mut self) -> io::Result<()> {
if self.viewport.resize_behavior == ResizeBehavior::Auto {
let size = self.size()?;
if size != self.viewport.area {
self.resize(size)?;
}
};
Ok(())
}
/// Synchronizes terminal size, calls the rendering closure, flushes the current internal state
/// and prepares for the next draw call.
pub fn draw(&mut self, cursor_position: Option<(u16, u16)>) -> io::Result<()> {
// // Autoresize - otherwise we get glitches if shrinking or potential desync between widgets
// // and the terminal (if growing), which may OOB.
// self.autoresize()?;
// let mut frame = self.get_frame();
// f(&mut frame);
// // We can't change the cursor position right away because we have to flush the frame to
// // stdout first. But we also can't keep the frame around, since it holds a &mut to
// // Terminal. Thus, we're taking the important data out of the Frame and dropping it.
// let cursor_position = frame.cursor_position;
// Draw to stdout
self.flush()?;
match cursor_position {
None => self.hide_cursor()?,
Some((x, y)) => {
self.show_cursor()?;
self.set_cursor(x, y)?;
}
}
// Swap buffers
self.buffers[1 - self.current].reset();
self.current = 1 - self.current;
// Flush
self.backend.flush()?;
Ok(())
}
pub fn hide_cursor(&mut self) -> io::Result<()> {
self.backend.hide_cursor()?;
self.hidden_cursor = true;
Ok(())
}
pub fn show_cursor(&mut self) -> io::Result<()> {
self.backend.show_cursor()?;
self.hidden_cursor = false;
Ok(())
}
pub fn get_cursor(&mut self) -> io::Result<(u16, u16)> {
self.backend.get_cursor()
}
pub fn set_cursor(&mut self, x: u16, y: u16) -> io::Result<()> {
self.backend.set_cursor(x, y)
}
/// Clear the terminal and force a full redraw on the next draw call.
pub fn clear(&mut self) -> io::Result<()> {
self.backend.clear()?;
// Reset the back buffer to make sure the next update will redraw everything.
self.buffers[1 - self.current].reset();
Ok(())
}
/// Queries the real size of the backend.
pub fn size(&self) -> io::Result<Rect> {
self.backend.size()
}
}
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