ffi-ncurses
Author: Sean O’Halpin
A pure-ruby wrapper for / ncursesw 5.x using the 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 report them). Having said that, you can do quite a lot with it as it is.
Install
$ [sudo] gem install ffi-ncurses
Usage
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
Set up screen
require 'ffi-ncurses'
FFI::NCurses.initscr
begin
...
ensure
FFI::NCurses.endwin
end
Typical initialization
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)
Colours
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.
Cursor
Turn cursor off
FFI::NCurses.curs_set 0
Turn cursor on
FFI::NCurses.curs_set 1
Windows
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
Panels
See examples/panel_simple.rb
for how to use panels.
Mouse handling
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.
Specifying which curses library to use
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
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 asstdscr
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
Issues
Please report any issues on the github issues page.
Trivia
While researching ncurses on Google, I innocently entered “curses getsx” as a search term. NSFW and definitely not one for “I’m Feeling Lucky”.
TO DO
Tests
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.
Tidy up internals and examples
Things got a bit messy as I switched between the Linux and Mac versions. The examples should be more focussed.
Credits
Thanks to rahul and manveru for their support!