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https://github.com/johnnovak/illwill

A curses inspired simple cross-platform console library for Nim
https://github.com/johnnovak/illwill

gui nim nim-lang terminal tui

Last synced: 20 days ago
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A curses inspired simple cross-platform console library for Nim

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README 

        
# illwill



## Overview



**illwill** is a *(n)curses* inspired simple terminal library that aims to make

writing cross-platform text mode applications easy. Having said that, it's

much simpler than (n)curses and it's not as robust by far in terms of

supporting different encodings, terminal types, etc. The aim was to write

something small and simple in pure Nim that works for 99% of users without

requiring any external dependencies or a terminfo database.



For "serious" applications, the best is always to write different backends for

*nix and Windows (one of the main reasons being that the Windows Console is

buffer based, not file based). But I think this library is perfect for small

cross-platform programs and utilities where you need something more than the

basic blocking console I/O, but you don't actually want to bother with

a full-blown GUI.



### Main features



* **Non-blocking** keyboard input.

* Support for **key combinations** and **special keys** available both in the standard

  Windows Console (`cmd.exe`) and most common POSIX terminals.

* **Virtual terminal buffers** with **double-buffering** support (only display changes

  from the previous frame and minimise the number of attribute changes to

  reduce CPU usage).

* Simple graphics using **UTF-8 box drawing** symbols.

* **Full-screen support** with restoring the contents of the terminal after exit.

* **Mouse support** with modifier key reporting.

* **No dependencies**—only depends on the standard terminal module.



illwill in action

illwill in action





nim-mod is an oldschool MOD

player that uses illwill for its awesome text-mode user interface



### Use it if



* You just want something simple that lets you write full-screen terminal

  apps with non-blocking keyboard input that work on Windows, Mac OS X and

  99.99% of modern Linux distributions.

* You don't need to support any fancy encodings and terminal types other than

  UTF-8.

* You're developing a custom UI so you don't need any predefined widgets.

* You don't mind the [immediate mode UI](https://github.com/ocornut/imgui)

  style/approach.

* You absolutely don't want any external dependencies.



### Projects using illwill



- [nim-mod](https://github.com/johnnovak/nim-mod) — A Nim MOD player just for fun 

- [ttop](https://github.com/inv2004/ttop) — System monitoring tool with historical data service, triggers and top-like TUI

- [promexplorer](https://github.com/marcusramberg/promexplorer) — A simple tool to explore Prometheus exporter metrics

- [clipclap](https://github.com/tttardigrado/clipclap) — A terminal-based ClipBoard Manager written in Nim

- [illwillWidgets](https://github.com/enthus1ast/illwillWidgets) — Mouse enabled widgets for illwill

- [tui_widget](https://github.com/jaar23/tui_widget) — Terminal UI widgets based on illwill

- [nimSnake](https://github.com/ColTrez/nimSnake) — Classic game of snake implemented in nim using the illwill TUI library for graphics



### Don't use it if



* You need ultimate robustness in terms of supporting obscure terminals,

  character encodings and Linux/Unix distributions.

* You need predefined widgets.

* You like complicating your life :sunglasses:



### Limitations & known issues



* Suspend/resume (SIGTSTP/SIGCONT handling) works, but it doesn't properly

  reset the terminal when suspending the app.

* The contents of the terminal is not restored after exiting a full-screen app

  on Windows.



## Installation



The best way to install the library is by using

[nimble](https://github.com/nim-lang/nimble):



```

nimble install illwill

```



## Documentation



https://www.johnnovak.net/illwill/



## Usage



This is a simple example on the general structure of a fullscreen terminal

application. Check out the [examples](/examples) for more advanced use cases

(e.g. using box drawing buffers, handling terminal resizes, etc.)



```nimrod

import os, strutils

import illwill



# 1. Initialise terminal in fullscreen mode and make sure we restore the state

# of the terminal state when exiting.

proc exitProc() {.noconv.} =

  illwillDeinit()

  showCursor()

  quit(0)



illwillInit(fullscreen=true)

setControlCHook(exitProc)

hideCursor()



# 2. We will construct the next frame to be displayed in this buffer and then

# just instruct the library to display its contents to the actual terminal

# (double buffering is enabled by default; only the differences from the

# previous frame will be actually printed to the terminal).

var tb = newTerminalBuffer(terminalWidth(), terminalHeight())



# 3. Display some simple static UI that doesn't change from frame to frame.

tb.setForegroundColor(fgBlack, true)

tb.drawRect(0, 0, 40, 5)

tb.drawHorizLine(2, 38, 3, doubleStyle=true)



tb.write(2, 1, fgWhite, "Press any key to display its name")

tb.write(2, 2, "Press ", fgYellow, "ESC", fgWhite,

               " or ", fgYellow, "Q", fgWhite, " to quit")



# 4. This is how the main event loop typically looks like: we keep polling for

# user input (keypress events), do something based on the input, modify the

# contents of the terminal buffer (if necessary), and then display the new

# frame.

while true:

  var key = getKey()

  case key

  of Key.None: discard

  of Key.Escape, Key.Q: exitProc()

  else:

    tb.write(8, 4, ' '.repeat(31))

    tb.write(2, 4, resetStyle, "Key pressed: ", fgGreen, $key)



  tb.display()

  sleep(20)



```



## License



Copyright © 2018-2024 John Novak <>



This work is free. You can redistribute it and/or modify it under the terms of

the [Do What The Fuck You Want To Public License, Version 2](http://www.wtfpl.net/), as published

by Sam Hocevar. See the [COPYING](./COPYING) file for more details.