Author: Sean O’Halpin

A pure-ruby wrapper for {invisible-island.net/ncurses/ ncursesw 5.x} using the {github.com/ffi/ffi ffi} library.

All of the core ncursesw functions are supported along with the Panel library. The main things left to do are support for the Menu and Form libraries.

The API is a transliteration of the C API rather than an attempt to provide an idiomatic Ruby object-oriented API. The intent is to provide a ‘close to the metal’ wrapper around the ncurses library upon which you can build your own abstractions.

Please note that this documentation does not cover individual ncursesw methods. For that you’ll need to refer to existing ncursesw documentation. For example, to find out about addstr, use:

$ man addstr

One benefit of using a minimal wrapper approach is that you can use existing examples and man pages to find out how to use the library. To get an overview of ncurses, use:

$ man ncurses

Having said that, this release also includes a wrapper that emulates the existing Ncurses library API. To use it, substitute

require 'ffi-ncurses/ncurses'

for

require 'ncurses'

or create a file called ‘ncurses.rb’ on your +$LOAD_PATH+ ($:) that requires ffi-ncurses/ncurses.rb.

Below you’ll find some very preliminary notes on usage. See the examples directory for real working examples, which among other things show how to input and output UTF-8, deal with pointers and handle wide characters.

This version of ffi-ncurses defaults to loading ncursesw, the ‘wide character’ version which supports UTF-8 and double width characters.

Tested on Ubuntu 10.04 with ruby1.8.7 and 1.9.2 using ffi (>= 0.6.3) and JRuby 1.6.4 (head). A previous version of the library was tested on Mac OS X 10.04. Please let me know if anything has stopped working.

Rubinius is not supported as its FFI does not provide the required API, especially for dealing with buffers and pointers.

This is still very much a work-in-progress, so expect some rough edges (and please {github.com/seanohalpin/ffi-ncurses/issues report them}). Having said that, you can do quite a lot with it as it is.

$ [sudo] gem install ffi-ncurses

Load the library with:

require 'ffi-ncurses'

FFI::NCurses methods can be called as module methods:

begin
  FFI::NCurses.initscr
  FFI::NCurses.clear
  FFI::NCurses.addstr("Hello world!")
  FFI::NCurses.refresh
  FFI::NCurses.getch
ensure
  FFI::NCurses.endwin
end

or as included methods:

include FFI::NCurses

begin
  initscr
  cbreak
  noecho
  curs_set 0
  clear
  move 10, 10
  standout
  addstr("Hi!")
  standend
  refresh
  getch
ensure
  endwin
end

require 'ffi-ncurses'

FFI::NCurses.initscr
begin
  ...
ensure
  FFI::NCurses.endwin
end

FFI::NCurses.initscr
FFI::NCurses.start_color
FFI::NCurses.curs_set 0
FFI::NCurses.raw
FFI::NCurses.noecho
FFI::NCurses.keypad(FFI::NCurses.stdscr, true)

start_color
init_pair(1, FFI::NCurses::COLOR_BLACK, FFI::NCurses::COLOR_RED)
attr_set FFI::NCurses::A_NORMAL, 1, nil
addch("A"[0].ord) # works in both 1.8.7 and 1.9.x
addch("Z"[0].ord | COLOR_PAIR(1))

See examples/color.rb for an example of use.

FFI::NCurses.curs_set 0

FFI::NCurses.curs_set 1

require 'ffi-ncurses'
include FFI::NCurses
begin
  initscr
  win = newwin(6, 12, 15, 15)
  box(win, 0, 0)
  inner_win = newwin(4, 10, 16, 16)
  waddstr(inner_win, (["Hello!"] * 5).join(' '))
  wrefresh(win)
  wrefresh(inner_win)
  ch = wgetch(inner_win)
  delwin(win)

rescue => e
  FFI::NCurses.endwin
  raise
ensure
  FFI::NCurses.endwin
end

See examples/panel_simple.rb for how to use panels.

NOTE: In previous versions of ffi-ncurses, the ncurses mouse API was included separately. You now no longer need to require 'ffi-ncurses/mouse' to get mouse support.

To use the mouse with ffi-ncurses, you first need to specify that you want keypad translation with:

keypad stdscr, true

otherwise your program will receive the raw mouse escape codes, instead of KEY_MOUSE mouse event codes.

Specify which events you want to handle with:

mousemask(ALL_MOUSE_EVENTS | REPORT_MOUSE_POSITION, nil)

and set up a mouse event structure to receive the returned values:

mouse_event = FFI::NCurses::MEVENT.new

Receiving mouse events is a two-stage process: first, you are notified that a mouse event has taken place through a special key code, then you retrieve the event using getmouse. For example:

ch = getch
case ch
when FFI::NCurses::KEY_MOUSE
  if getmouse(mouse_event) == FFI::NCurses::OK

The mouse event contains the button state (bstate) and x, y coordinates. You can test for the button state using:

if mouse_event[:bstate] & FFI::NCurses::BUTTON1_PRESSED

or

if FFI::NCurses.BUTTON_PRESS(mouse_event[:bstate], 1)

The possible button states are: PRESS, RELEASE, CLICK, DOUBLE_CLICK and TRIPLE_CLICK.

See examples/mouse.rb for a complete example.

You can specify which variant of curses you want to use by setting the environment variable RUBY_FFI_NCURSES_LIB to the one you want. For example, to use the PDCurses X11 curses lib, use:

RUBY_FFI_NCURSES_LIB=XCurses ruby examples/example.rb

You could also use this to specify ncursesw-dbg for example to get access to the trace functions.

examples/acs_chars.rb

How to display box drawing characters

examples/attributes.rb

How to set attributes

examples/color.rb

How to initialize and use colour

examples/cursor.rb

How to turn the cursor on and off

examples/doc-eg1.rb

Example 1 from the documentation

examples/doc-eg2.rb

Example 2 from the documentation

examples/doc-eg3.rb

Example 3 from the documentation

examples/example.rb

An example showing off the main features of ncurses

examples/getkey.rb

How to get Unicode input

examples/getsetsyx.rb

Shows how to use the getsetyx function

examples/globals.rb

Display ncurses global variables

examples/hello.rb

Hello world

examples/hellowide.rb

Hello world using wide characters

examples/keys.rb

How to use the getch function. See getkey for a more general solution

examples/mouse.rb

How to use the mouse

examples/multiterm.rb

How to display on more than one tty

examples/newterm.rb

How to use newterm so you can pipe stdin into an ncurses program

examples/panel_simple.rb

How to use panels

examples/printw-variadic.rb

How to call the printw method

examples/ripoffline.rb

An example of the ripoffline method

examples/softkeys.rb

How to set up soft keys (function key labels)

examples/stdscr.rb

Shows that initscr returns same value as stdscr

examples/temp_leave.rb

How to temporarily shell out from an ncurses program

examples/viewer.rb

A simple file viewer (lesser than less) that shows how to use pads and pop up windows

examples/wacs_chars.rb

How to display wide (Unicode) box drawing characters

examples/windows.rb

Move a window about the screen

Please report any issues on the {github.com/seanohalpin/ffi-ncurses/issues github issues} page.

While researching ncurses on Google, I innocently entered “curses getsx” as a search term. NSFW and definitely not one for “I’m Feeling Lucky”.

This is tricky - I’m not sure exactly how to properly test a wrapper for a library like ncurses. I certainly don’t want to test ncurses! Instead, I want to ensure my wrapper faithfully reproduces the functionality of the platform’s ncurses lib. To that end, I’m experimenting with a simple DSL to generate both C and Ruby versions of a test. With that I can generate equivalent programs and compare the output. However, this is not really ready for prime time yet.

Things got a bit messy as I switched between the Linux and Mac versions. The examples should be more focussed.

Thanks to rahul and manveru for their support!