pub struct CrosstermBackend<W: Write> { /* private fields */ }Expand description
A Backend implementation based on the crossterm crate.
CrosstermBackend renders terminal output using Crossterm escape sequences
and works on most platforms, including Windows, macOS, and Linux.
This backend is intended to be used together with [Terminal] and provides
low-level drawing primitives such as cursor movement, color and attribute
management, screen clearing, and buffer flushing.
§Responsibilities
- render cells to the terminal using Crossterm commands
- manage cursor visibility and position
- query terminal size
- clear and flush the terminal output
§What this backend does not do
- enable or disable raw mode
- enter or leave the alternate screen
- handle mouse input
- manage terminal lifetime
Terminal setup and teardown are expected to be handled externally
(for example, by [Altui] or manual Crossterm calls).
§Usage
In most applications, you should prefer using [Altui] instead of
constructing a CrosstermBackend directly.
§See also
- [
Altui] - [
Terminal] - [
backend::Backend]
Implementations§
Source§impl<W> CrosstermBackend<W>where
W: Write,
impl<W> CrosstermBackend<W>where
W: Write,
Sourcepub fn new(buffer: W) -> CrosstermBackend<W> ⓘ
pub fn new(buffer: W) -> CrosstermBackend<W> ⓘ
Creates a new CrosstermBackend using the given output buffer.
The buffer is typically std::io::Stdout, but any type implementing
Write may be used.
§Parameters
buffer: the output target for terminal commands
§Notes
This function does not perform any terminal initialization. Raw mode, alternate screen handling, and mouse capture must be managed by the caller.
Trait Implementations§
Source§impl<W> Backend for CrosstermBackend<W>where
W: Write,
impl<W> Backend for CrosstermBackend<W>where
W: Write,
Source§fn draw<'a, I>(&mut self, content: I) -> Result<()>
fn draw<'a, I>(&mut self, content: I) -> Result<()>
Draws an iterator of cells to the terminal.
The iterator yields (x, y, &Cell) tuples, which are rendered using
efficient cursor movement and minimal attribute changes.
The backend internally tracks:
- foreground color
- background color
- text modifiers
- cursor position
to reduce the number of Crossterm commands sent to the terminal.
§Errors
Returns an error if writing to the output buffer fails.
Source§fn hide_cursor(&mut self) -> Result<()>
fn hide_cursor(&mut self) -> Result<()>
Hides the terminal cursor.
Source§fn show_cursor(&mut self) -> Result<()>
fn show_cursor(&mut self) -> Result<()>
Shows the terminal cursor.
Source§fn get_cursor(&mut self) -> Result<(u16, u16)>
fn get_cursor(&mut self) -> Result<(u16, u16)>
Returns the current cursor position.
The position is reported in terminal coordinates.
Source§fn set_cursor(&mut self, x: u16, y: u16) -> Result<()>
fn set_cursor(&mut self, x: u16, y: u16) -> Result<()>
Moves the cursor to the given position.
Source§impl<W> Write for CrosstermBackend<W>where
W: Write,
CrosstermBackend forwards all Write calls to the underlying buffer.
impl<W> Write for CrosstermBackend<W>where
W: Write,
CrosstermBackend forwards all Write calls to the underlying buffer.
This allows it to be used seamlessly with APIs that expect a writable output stream.
Source§fn write(&mut self, buf: &[u8]) -> Result<usize>
fn write(&mut self, buf: &[u8]) -> Result<usize>
Source§fn flush(&mut self) -> Result<()>
fn flush(&mut self) -> Result<()>
Source§fn is_write_vectored(&self) -> bool
fn is_write_vectored(&self) -> bool
can_vector)1.0.0 · Source§fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>
fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>
Source§fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>
fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>
write_all_vectored)Auto Trait Implementations§
impl<W> Freeze for CrosstermBackend<W>where
W: Freeze,
impl<W> RefUnwindSafe for CrosstermBackend<W>where
W: RefUnwindSafe,
impl<W> Send for CrosstermBackend<W>where
W: Send,
impl<W> Sync for CrosstermBackend<W>where
W: Sync,
impl<W> Unpin for CrosstermBackend<W>where
W: Unpin,
impl<W> UnsafeUnpin for CrosstermBackend<W>where
W: UnsafeUnpin,
impl<W> UnwindSafe for CrosstermBackend<W>where
W: UnwindSafe,
Blanket Implementations§
Source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
Source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Source§impl<T> ExecutableCommand for T
impl<T> ExecutableCommand for T
Source§fn execute(&mut self, command: impl Command) -> Result<&mut T, Error>
fn execute(&mut self, command: impl Command) -> Result<&mut T, Error>
Executes the given command directly.
The given command its ANSI escape code will be written and flushed onto Self.
§Arguments
-
The command that you want to execute directly.
§Example
use std::io;
use crossterm::{ExecutableCommand, style::Print};
fn main() -> io::Result<()> {
// will be executed directly
io::stdout()
.execute(Print("sum:\n".to_string()))?
.execute(Print(format!("1 + 1= {} ", 1 + 1)))?;
Ok(())
// ==== Output ====
// sum:
// 1 + 1 = 2
}Have a look over at the Command API for more details.
§Notes
- In the case of UNIX and Windows 10, ANSI codes are written to the given ‘writer’.
- In case of Windows versions lower than 10, a direct WinAPI call will be made.
The reason for this is that Windows versions lower than 10 do not support ANSI codes,
and can therefore not be written to the given
writer. Therefore, there is no difference between execute and queue for those old Windows versions.
Source§impl<T> Instrument for T
impl<T> Instrument for T
Source§fn instrument(self, span: Span) -> Instrumented<Self>
fn instrument(self, span: Span) -> Instrumented<Self>
Source§fn in_current_span(self) -> Instrumented<Self>
fn in_current_span(self) -> Instrumented<Self>
Source§impl<T> QueueableCommand for T
impl<T> QueueableCommand for T
Source§fn queue(&mut self, command: impl Command) -> Result<&mut T, Error>
fn queue(&mut self, command: impl Command) -> Result<&mut T, Error>
Queues the given command for further execution.
Queued commands will be executed in the following cases:
- When
flushis called manually on the given type implementingio::Write. - The terminal will
flushautomatically if the buffer is full. - Each line is flushed in case of
stdout, because it is line buffered.
§Arguments
-
The command that you want to queue for later execution.
§Examples
use std::io::{self, Write};
use crossterm::{QueueableCommand, style::Print};
fn main() -> io::Result<()> {
let mut stdout = io::stdout();
// `Print` will executed executed when `flush` is called.
stdout
.queue(Print("foo 1\n".to_string()))?
.queue(Print("foo 2".to_string()))?;
// some other code (no execution happening here) ...
// when calling `flush` on `stdout`, all commands will be written to the stdout and therefore executed.
stdout.flush()?;
Ok(())
// ==== Output ====
// foo 1
// foo 2
}Have a look over at the Command API for more details.
§Notes
- In the case of UNIX and Windows 10, ANSI codes are written to the given ‘writer’.
- In case of Windows versions lower than 10, a direct WinAPI call will be made.
The reason for this is that Windows versions lower than 10 do not support ANSI codes,
and can therefore not be written to the given
writer. Therefore, there is no difference between execute and queue for those old Windows versions.
Source§impl<W> SynchronizedUpdate for W
impl<W> SynchronizedUpdate for W
Source§fn sync_update<T>(
&mut self,
operations: impl FnOnce(&mut W) -> T,
) -> Result<T, Error>
fn sync_update<T>( &mut self, operations: impl FnOnce(&mut W) -> T, ) -> Result<T, Error>
Performs a set of actions within a synchronous update.
Updates will be suspended in the terminal, the function will be executed against self, updates will be resumed, and a flush will be performed.
§Arguments
-
Function
A function that performs the operations that must execute in a synchronized update.
§Examples
use std::io;
use crossterm::{ExecutableCommand, SynchronizedUpdate, style::Print};
fn main() -> io::Result<()> {
let mut stdout = io::stdout();
stdout.sync_update(|stdout| {
stdout.execute(Print("foo 1\n".to_string()))?;
stdout.execute(Print("foo 2".to_string()))?;
// The effects of the print command will not be present in the terminal
// buffer, but not visible in the terminal.
std::io::Result::Ok(())
})?;
// The effects of the commands will be visible.
Ok(())
// ==== Output ====
// foo 1
// foo 2
}§Notes
This command is performed only using ANSI codes, and will do nothing on terminals that do not support ANSI codes, or this specific extension.
When rendering the screen of the terminal, the Emulator usually iterates through each visible grid cell and renders its current state. With applications updating the screen a at higher frequency this can cause tearing.
This mode attempts to mitigate that.
When the synchronization mode is enabled following render calls will keep rendering the last rendered state. The terminal Emulator keeps processing incoming text and sequences. When the synchronized update mode is disabled again the renderer may fetch the latest screen buffer state again, effectively avoiding the tearing effect by unintentionally rendering in the middle a of an application screen update.