tui-textarea

tui-textarea is a simple yet powerful text editor widget like <textarea> in HTML for tui-rs and ratatui. Multi-line text editor can be easily put as part of your TUI application.

Features:

• Multi-line text editor widget with basic operations (insert/delete characters, auto scrolling, ...)
• Emacs-like shortcuts (C-n/C-p/C-f/C-b, M-f/M-b, C-a/C-e, C-h/C-d, C-k, M-</M->, ...)
• Undo/Redo
• Line number
• Cursor line highlight
• Search with regular expressions
• Mouse scrolling
• Yank support. Paste text deleted with C-k, C-j, ...
• Backend agnostic. crossterm, termion, and your own backend are all supported
• Multiple textarea widgets in the same screen
• Support both tui-rs (the original) and ratatui (the fork by community)

Documentation

Examples

Running cargo run --example in this repository can demonstrate usage of tui-textarea.

minimal

cargo run --example minimal

Minimal usage with crossterm support.

editor

cargo run --example editor --features search file.txt

Simple text editor to edit multiple files.

single_line

cargo run --example single_line

Single-line input form with float number validation.

split

cargo run --example split

Two split textareas in a screen and switch them. An example for multiple textarea instances.

termion

cargo run --example termion --features=termion

Minimal usage with termion support.

variable

cargo run --example variable

Simple textarea with variable height following the number of lines.

modal

cargo run --example modal

Simple modal text editor like vi.

Examples for ratatui support

All above examples uses tui-rs, but some examples provide ratatui version. Try ratatui_ prefix. In these cases, you need to specify features to use ratatui and --no-default-features flag explicitly.

# ratatui version of `minimal` example
cargo run --example ratatui_minimal --no-default-features --features=ratatui-crossterm

# ratatui version of `editor` example
cargo run --example ratatui_editor --no-default-features --features=ratatui-crossterm,search file.txt

# ratatui version of `termion` example
cargo run --example ratatui_termion --no-default-features --features=ratatui-termion

Installation

Add tui-textarea crate to dependencies in your Cargo.toml. This enables crossterm backend support by default.

[dependencies]
tui = "*"
tui-textarea = "*"

If you need text search with regular expressions, enable search feature. It adds regex crate crate as dependency.

[dependencies]
tui = "*"
tui-textarea = { version = "*", features = ["search"] }

If you're using tui-rs with termion, enable termion feature instead of crossterm feature.

[dependencies]
tui = { version = "*", default-features = false, features = ["termion"] }
tui-textarea = { version = "*", default-features = false, features = ["termion"] }

If you're using ratatui instead of tui-rs, you need to enable features for using ratatui crate. The following table shows feature names corresponding to the dependencies.

For example, when you want to use the combination of ratatui and crossterm,

[dependencies]
ratatui = "*"
tui-textarea = { version = "*", features = ["ratatui-crossterm"], default-features=false }

Note that tui-rs support and ratatui support are exclusive. When you use ratatui support, you must disable tui-rs support by default-features=false.

In addition to above dependencies, you also need to install crossterm or termion to initialize your application and to receive key inputs. Note that version of crossterm crate is different between tui-rs and ratatui. Please select the correct version.

Minimal Usage

use tui_textarea::TextArea;
use crossterm::event::{Event, read};

let mut term = tui::Terminal::new(...);

// Create an empty `TextArea` instance which manages the editor state
let mut textarea = TextArea::default();

// Event loop
loop {
    term.draw(|f| {
        // Get `tui::layout::Rect` where the editor should be rendered
        let rect = ...;
        // `TextArea::widget` builds a widget to render the editor with tui
        let widget = textarea.widget();
        // Render the widget in terminal screen
        f.render_widget(widget, rect);
    })?;

    if let Event::Key(key) = read()? {
        // Your own key mapping to break the event loop
        if key.code == KeyCode::Esc {
            break;
        }
        // `TextArea::input` can directly handle key events from backends and update the editor state
        textarea.input(key);
    }
}

// Get text lines as `&[String]`
println!("Lines: {:?}", textarea.lines());

TextArea is an instance to manage the editor state. By default, it disables line numbers and highlights cursor line with underline.

TextArea::widget() builds a widget to render the current state of the editor. Create the widget and render it on each tick of event loop.

TextArea::input() receives inputs from tui backends. The method can take key events from backends such as crossterm::event::KeyEvent or termion::event::Key directly if the features are enabled. The method handles default key mappings as well.

Default key mappings are as follows:

Deleting multiple characters at once saves the deleted text to yank buffer. It can be pasted with Ctrl+Y later.

If you don't want to use default key mappings, see the 'Advanced Usage' section.

Basic Usage

Create TextArea instance with text

TextArea implements Default trait to create an editor instance with an empty text.

let mut textarea = TextArea::default();

TextArea::new() creates an editor instance with text lines passed as Vec<String>.

let mut lines: Vec<String> = ...;
let mut textarea = TextArea::new(lines);

TextArea implements From<impl Iterator<Item=impl Into<String>>>. TextArea::from() can create an editor instance from any iterators whose elements can be converted to String.

// Create `TextArea` from from `[&str]`
let mut textarea = TextArea::from([
    "this is first line",
    "this is second line",
    "this is third line",
]);

// Create `TextArea` from `String`
let mut text: String = ...;
let mut textarea = TextARea::from(text.lines());

TextArea also implements FromIterator<impl Into<String>>. Iterator::collect() can collect strings as an editor instance. This allows to create TextArea reading lines from file efficiently using io::BufReader.

let file = fs::File::open(path)?;
let mut textarea: TextArea = io::BufReader::new(file).lines().collect::<io::Result<_>>()?;

Get text contents from TextArea

TextArea::lines() returns text lines as &[String]. It borrows text contents temporarily.

let text: String = textarea.lines().join("\n");

TextArea::into_lines() moves TextArea instance into text lines as Vec<String>. This can retrieve the text contents without any copy.

let lines: Vec<String> = textarea.into_lines();

Note that TextArea always contains at least one line. For example, an empty text means one empty line. This is because any text file must end with newline.

let textarea = TextArea::default();
assert_eq!(textarea.into_lines(), [""]);

Show line number

By default, TextArea does now show line numbers. To enable, set a style for rendering line numbers by TextArea::set_line_number_style(). For example, the following renders line numbers in dark gray background color.

use tui::style::{Style, Color};

let style = Style::default().bg(Color::DarkGray);
textarea.set_line_number_style(style);

Configure cursor line style

By default, TextArea renders the line at cursor with underline so that users can easily notice where the current line is. To change the style of cursor line, use TextArea::set_cursor_line_style(). For example, the following styles the cursor line with bold text.

use tui::style::{Style, Modifier};

let style = Style::default().add_modifier(Modifier::BOLD);
textarea.set_line_number_style(style);

To disable cursor line style, set the default style as follows:

use tui::style::{Style, Modifier};

textarea.set_line_number_style(Style::default());

Configure tab width

The default tab width is 4. To change it, use TextArea::set_tab_length() method. The following sets 2 to tab width. Typing tab key inserts 2 spaces.

textarea.set_tab_length(2);

Configure max history size

By default, past 50 modifications are stored as edit history. The history is used for undo/redo. To change how many past edits are remembered, use TextArea::set_max_histories() method. The following remembers past 1000 changes.

textarea.set_max_histories(1000);

Setting 0 disables undo/redo.

textarea.set_max_histories(0);

Text search with regular expressions

To search text in textarea, set a regular expression pattern with TextArea::set_search_pattern() and move cursor with TextArea::search_forward() for forward search or TextArea::search_back() backward search. The regular expression is handled by regex crate.

Text search wraps around the textarea. When searching forward and no match found until the end of textarea, it searches the pattern from start of the file.

Matches are highlighted in textarea. The text style to highlight matches can be changed with TextArea::set_search_style(). Setting an empty string to TextArea::set_search_pattern() stops the text search.

// Start text search matching to "hello" or "hi". This highlights matches in textarea but does not move cursor.
// `regex::Error` is returned on invalid pattern.
textarea.set_search_pattern("(hello|hi)").unwrap();

textarea.search_forward(false); // Move cursor to the next match
textarea.search_back(false);    // Move cursor to the previous match

// Setting empty string stops the search
textarea.set_search_pattern("").unwrap();

No UI is provided for text search. You need to provide your own UI to input search query. It is recommended to use another TextArea for search form. To build a single-line input form, see 'Single-line input like <input> in HTML' in 'Advanced Usage' section below.

editor example implements a text search with search form built on TextArea. See the implementation for working example.

To use text search, search feature needs to be enabled in your Cargo.toml. It is disabled by default to avoid depending on regex crate until it is necessary.

tui-textarea = { version = "*", features = ["search"] }

Advanced Usage

Single-line input like <input> in HTML

To use TextArea for single-line input widget like <input> in HTML, ignore all key mappings which inserts newline.

use crossterm::event::{Event, read};
use tui_textarea::{Input, Key};

let default_text: &str = ...;
let default_text = default_text.replace(&['\n', '\r'], " "); // Ensure no new line is contained
let mut textarea = TextArea::new(vec![default_text]);

// Event loop
loop {
    // ...

    // Using `Input` is not mandatory, but it's useful for pattern match
    // Ignore Ctrl+m and Enter. Otherwise handle keys as usual
    match read()?.into() {
        Input { key: Key::Char('m'), ctrl: true, alt: false }
        | Input { key: Key::Enter, .. } => continue,
        input => {
            textarea.input(key);
        }
    }
}

let text = textarea.into_lines().remove(0); // Get input text

See single_line example for working example.

Define your own key mappings

All editor operations are defined as public methods of TextArea. To move cursor, use tui_textarea::CursorMove to notify how to move the cursor.

To define your own key mappings, simply call the above methods in your code instead of TextArea::input() method. The following example defines modal key mappings like Vim.

use crossterm::event::{Event, read};
use tui_textarea::{Input, Key, CursorMove, Scrolling};

let mut textarea = ...;

enum Mode {
    Normal,
    Insert,
}

let mut mode = Mode::Normal;

// Event loop
loop {
    // ...

    match mode {
        Mode::Normal => match read()?.into() {
            Input { key: Key::Char('h'), .. } => textarea.move_cursor(CursorMove::Back),
            Input { key: Key::Char('j'), .. } => textarea.move_cursor(CursorMove::Down),
            Input { key: Key::Char('k'), .. } => textarea.move_cursor(CursorMove::Up),
            Input { key: Key::Char('l'), .. } => textarea.move_cursor(CursorMove::Forward),
            Input { key: Key::Char('i'), .. } => mode = Mode::Insert, // Enter insert mode
            // ...Add more mappings
            _ => {},
        },
        Mode::Insert => match read()?.into() {
            Input { key: Key::Esc, .. } => {
                mode = Mode::Normal; // Back to normal mode with Esc or Ctrl+C
            }
            input => {
                textarea.input(input); // Use default key mappings in insert mode
            }
        },
    }
}

See modal example for working example. It implements more Vim-like key mappings.

If you don't want to use default key mappings, TextArea::input_without_shortcuts() method can be used instead of TextArea::input(). The method only handles very basic operations such as inserting/deleting single characters, tabs, newlines.

match read()?.into() {
    // Handle your own key mappings here
    // ...
    input => textarea.input_without_shortcuts(input),
}

Use your own backend

tui-rs allows to make your own backend by implementing tui::backend::Backend trait. tui-textarea also supports it. In this case, please use your-backend feature for tui-rs or ratatui-your-backend feature for ratatui. They avoid adding backend crates (crossterm and termion) since you're using your own backend.

[dependencies]
tui = { version = "*", default-features = false }
tui-textarea = { version = "*", default-features = false, features = ["your-backend"] }

tui_textarea::Input is a type for backend-agnostic key input. What you need to do is converting key event in your own backend into the tui_textarea::Input instance. Then TextArea::input() method can handle the input as other backend.

In the following example, let's say your_backend::KeyDown is a key event type for your backend and your_backend::read_next_key() returns the next key event.

// In your backend implementation

pub enum KeyDown {
    Char(char),
    BS,
    Del,
    Esc,
    // ...
}

// Return tuple of (key, ctrlkey, altkey)
pub fn read_next_key() -> (KeyDown, bool, bool) {
    // ...
}

Then you can implement the logic to convert your_backend::KeyDown value into tui_textarea::Input value.

use tui_textarea::{Input, Key};
use your_backend::KeyDown;

fn keydown_to_input(key: KeyDown, ctrl: bool, alt: bool) -> Input {
    match key {
        KeyDown::Char(c) => Input { key: Key::Char(c), ctrl, alt },
        KeyDown::BS => Input { key: Key::Backspace, ctrl, alt },
        KeyDown::Del => Input { key: Key::Delete, ctrl, alt },
        KeyDown::Esc => Input { key: Key::Esc, ctrl, alt },
        // ...
        _ => Input::default(),
    }
}

For the keys which are not handled by tui-textarea, tui_textarea::Input::default() is available. It returns 'null' key. An editor will do nothing with the key.

Finally, convert your own backend's key input type into tui_textarea::Input and pass it to TextArea::input().

let mut textarea = ...;

// Event loop
loop {
    // ...

    let (key, ctrl, alt) = your_backend::read_next_key();
    if key == your_backend::KeyDown::Esc {
        break; // For example, quit your app on pressing Esc
    }
    textarea.input(keydown_to_input(key, ctrl, alt));
}

Put multiple TextArea instances in screen

You don't need to do anything special. Create multiple TextArea instances and render widgets built from each instances.

The following is an example to put two textarea widgets in application and manage the focus.

use tui_textarea::{TextArea, Input, Key};
use crossterm::event::{Event, read};

let editors = &mut [
    TextArea::default(),
    TextArea::default(),
];

let mut focused = 0;

loop {
    term.draw(|f| {
        let rects = ...;

        for (editor, rect) in editors.iter_mut().zip(rects.into_iter()) {
            let widget = editor.widget();
            f.render_widget(widget, rect);
        }
    })?;

    match read()?.into() {
        // Switch focused textarea by Ctrl+S
        Input { key: Key::Char('s'), ctrl: true, .. } => focused = (focused + 1) % 2;
        // Handle input by the focused editor
        input => editors[focused].input(input),
    }
}

See split example and editor example for working example.

Minimum Supported Rust Version

MSRV of this crate is depending on tui crate. Currently MSRV is 1.56.1.

Versioning

This crate is not reaching v1.0.0 yet. There is no plan to bump the major version for now. Current versioning policy is as follows:

• Major: Fixed to 0
• Minor: Bump on breaking change
• Patch: Bump on new feature or bug fix

Contributing to tui-textarea

This project is developed on GitHub.

For feature requests or bug reports, please create an issue. For submitting patches, please create a pull request.

Please see CONTRIBUTING.md before making a PR.

License

tui-textarea is distributed under The MIT License.