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|
use crate::error::*;
use std::io::Write as _;
use crate::private::Output as _;
/// Switches the terminal on `stdout` to alternate screen mode, and restores
/// it when this object goes out of scope.
pub struct ScreenGuard {
cleaned_up: bool,
}
impl ScreenGuard {
/// Switches the terminal on `stdout` to alternate screen mode and returns
/// a guard object. This is typically called as part of
/// [`Output::new`](Output::new).
pub fn new() -> Result<Self> {
write_stdout(crate::INIT)?;
Ok(Self { cleaned_up: false })
}
/// Switch back from alternate screen mode early.
pub fn cleanup(&mut self) -> Result<()> {
if self.cleaned_up {
return Ok(());
}
self.cleaned_up = true;
write_stdout(crate::DEINIT)
}
}
impl Drop for ScreenGuard {
/// Calls `cleanup`.
fn drop(&mut self) {
let _ = self.cleanup();
}
}
/// Manages drawing to the terminal on `stdout`.
///
/// Most functionality is provided by the [`Textmode`](crate::Textmode) trait.
/// You should call those trait methods to draw to the in-memory screen, and
/// then call [`refresh`](Output::refresh) when you want to update the
/// terminal on `stdout`.
pub struct Output {
screen: Option<ScreenGuard>,
cur: vt100::Parser,
next: vt100::Parser,
}
impl crate::private::Output for Output {
fn cur(&self) -> &vt100::Parser {
&self.cur
}
fn cur_mut(&mut self) -> &mut vt100::Parser {
&mut self.cur
}
fn next(&self) -> &vt100::Parser {
&self.next
}
fn next_mut(&mut self) -> &mut vt100::Parser {
&mut self.next
}
}
impl crate::Textmode for Output {}
impl Output {
/// Creates a new `Output` instance containing a
/// [`ScreenGuard`](ScreenGuard) instance.
pub fn new() -> Result<Self> {
let mut self_ = Self::new_without_screen();
self_.screen = Some(ScreenGuard::new()?);
Ok(self_)
}
/// Creates a new `Output` instance without creating a
/// [`ScreenGuard`](ScreenGuard) instance.
pub fn new_without_screen() -> Self {
let (rows, cols) = match terminal_size::terminal_size() {
Some((terminal_size::Width(w), terminal_size::Height(h))) => {
(h, w)
}
_ => (24, 80),
};
let cur = vt100::Parser::new(rows, cols, 0);
let next = vt100::Parser::new(rows, cols, 0);
Self {
screen: None,
cur,
next,
}
}
/// Removes the [`ScreenGuard`](ScreenGuard) instance stored in this
/// `Output` instance and returns it. This can be useful if you need to
/// manage the lifetime of the [`ScreenGuard`](ScreenGuard) instance
/// separately.
pub fn take_screen_guard(&mut self) -> Option<ScreenGuard> {
self.screen.take()
}
/// Draws the in-memory screen to the terminal on `stdout`. This is done
/// using a diff mechanism to only update the parts of the terminal which
/// are different from the in-memory screen.
pub fn refresh(&mut self) -> Result<()> {
let diff = self.next().screen().state_diff(self.cur().screen());
write_stdout(&diff)?;
self.cur_mut().process(&diff);
Ok(())
}
}
fn write_stdout(buf: &[u8]) -> Result<()> {
let mut stdout = std::io::stdout();
stdout.write_all(buf).map_err(Error::WriteStdout)?;
stdout.flush().map_err(Error::WriteStdout)?;
Ok(())
}
|
