termwiz: add very basic line editor

termwiz/examples/line_editor.rs

@@ -0,0 +1,15 @@
+use failure::Fallible;
+use termwiz::caps::Capabilities;
+use termwiz::lineedit::LineEditor;
+use termwiz::terminal::new_terminal;
+
+fn main() -> Fallible<()> {
+    let caps = Capabilities::new_from_env()?;
+    let terminal = new_terminal(caps)?;
+    let mut editor = LineEditor::new(terminal);
+
+    let line = editor.read_line()?;
+    println!("read line: {}", line);
+
+    Ok(())
+}

termwiz/src/lib.rs

@@ -43,6 +43,7 @@ pub mod image;
 pub mod input;
 pub mod istty;
 pub mod keymap;
+pub mod lineedit;
 mod readbuf;
 pub mod render;
 pub mod surface;

termwiz/src/lineedit/mod.rs

@@ -0,0 +1,62 @@
+use crate::input::{InputEvent, KeyCode, KeyEvent, Modifiers};
+use crate::surface::{Change, Position};
+use crate::terminal::Terminal;
+use failure::Fallible;
+
+pub struct LineEditor<T: Terminal> {
+    terminal: T,
+    line: String,
+}
+
+impl<T: Terminal> LineEditor<T> {
+    pub fn new(terminal: T) -> Self {
+        Self {
+            terminal,
+            line: String::new(),
+        }
+    }
+
+    fn render(&mut self) -> Fallible<()> {
+        self.terminal.render(&[
+            Change::CursorPosition {
+                x: Position::Absolute(0),
+                y: Position::NoChange,
+            },
+            Change::ClearToEndOfScreen(Default::default()),
+            Change::Text(self.line.clone()),
+        ])?;
+        Ok(())
+    }
+
+    pub fn read_line(&mut self) -> Fallible<String> {
+        self.terminal.set_raw_mode()?;
+        let res = self.read_line_impl();
+        self.terminal.set_cooked_mode()?;
+        println!();
+        res
+    }
+
+    fn read_line_impl(&mut self) -> Fallible<String> {
+        self.line.clear();
+        self.render()?;
+        while let Some(event) = self.terminal.poll_input(None)? {
+            match event {
+                InputEvent::Key(KeyEvent {
+                    key: KeyCode::Enter,
+                    modifiers: Modifiers::NONE,
+                }) => {
+                    break;
+                }
+                InputEvent::Key(KeyEvent {
+                    key: KeyCode::Char(c),
+                    modifiers: Modifiers::NONE,
+                }) => {
+                    self.line.push(c);
+                }
+                _ => {}
+            }
+            self.render()?;
+        }
+        Ok(self.line.clone())
+    }
+}

termwiz/src/render/terminfo.rs

@@ -452,6 +452,10 @@ impl TerminfoRenderer {
                     out.by_ref().write_all(b"\r\n")?;
                 }
                 Change::CursorPosition {
+                    x: Position::Absolute(0),
+                    y: Position::NoChange,
+                }
+                | Change::CursorPosition {
                     x: Position::Absolute(0),
                     y: Position::Relative(0),
                 } => {

termwiz/src/terminal/mod.rs

@@ -3,7 +3,7 @@
 use crate::caps::Capabilities;
 use crate::input::InputEvent;
 use crate::surface::Change;
-use failure::{format_err, Error};
+use failure::{format_err, Error, Fallible};
 use num::{self, NumCast};
 use std::fmt::Display;
 use std::time::Duration;
@@ -56,6 +56,7 @@ pub trait Terminal {
     /// pressed by the user do not implicitly render to the terminal
     /// output, and disables canonicalization of unix newlines to CRLF.
     fn set_raw_mode(&mut self) -> Result<(), Error>;
+    fn set_cooked_mode(&mut self) -> Fallible<()>;
 
     /// Enter the alternate screen.  The alternate screen will be left
     /// automatically when the `Terminal` is dropped.

termwiz/src/terminal/unix.rs

@@ -1,5 +1,5 @@
 use crate::istty::IsTty;
-use failure::{bail, ensure, format_err, Error};
+use failure::{bail, ensure, format_err, Error, Fallible};
 use libc::{self, poll, pollfd, winsize, POLLIN};
 use signal_hook::{self, SigId};
 use std::collections::VecDeque;
@@ -357,6 +357,11 @@ impl Terminal for UnixTerminal {
         Ok(())
     }
 
+    fn set_cooked_mode(&mut self) -> Fallible<()> {
+        self.write
+            .set_termios(&self.saved_termios, SetAttributeWhen::Now)
+    }
+
     fn enter_alternate_screen(&mut self) -> Result<(), Error> {
         if !self.in_alternate_screen {
             write!(

termwiz/src/terminal/windows.rs

@@ -521,6 +521,17 @@ impl Terminal for WindowsTerminal {
         )
     }
 
+    fn set_cooked_mode(&mut self) -> Fallible<()> {
+        let mode = self.input_handle.get_input_mode()?;
+
+        self.input_handle.set_input_mode(
+            (mode & !(ENABLE_WINDOW_INPUT | ENABLE_WINDOW_INPUT))
+                | ENABLE_ECHO_INPUT
+                | ENABLE_LINE_INPUT
+                | ENABLE_PROCESSED_INPUT,
+        )
+    }
+
     fn enter_alternate_screen(&mut self) -> Result<(), Error> {
         // TODO: Implement using CreateConsoleScreenBuffer and
         // SetConsoleActiveScreenBuffer.