Introduction

What is ooxcb?

ooxcb (the object oriented X C binding, yes, the C doesn’t fit here) is a new Python binding to the X server, developed for the samurai-x window manager. xpyb uses a wrapper generator to create python modules out of the XML X protocol descriptions of the xcb project. It aims to provide with an easy-to-use object-oriented interface to the X server.

Why?

There already is a similar project called xpyb which is able to create an usable Python module for every X extension supported by xcb-proto. However, the most important parts of xpyb are in a C extension, and we wanted samurai-x to be pure-python. So we ported the whole C code of xpyb to Python, just using some functions of the libxcb API invoked by the ctypes module (you can get it here, but beware: it’s a bit unstable). Apart from that, xpyb-generated bindings are very close to the X protocol. For every extension, you have one class that has some methods for each request. On the one hand, xpyb is able to cover all the extensions supported by xcb-proto this way; on the other hand, the binding is not very comfortable to use. Because of that, we decided to write our own binding, based on the xpyb-ctypes code (so, big thanks to xpyb!). The ooxcb wrapper generator uses so-called interface files that describe the desired Python API of a specific extension - so we can create an API that is more comfortable and easy-to-use. However, someone has to write these interface files, and depending on the size and complexity of the extension, that’s a time-intensive job. At the moment, everything of the xproto extension (the core extension) is wrapped, but some parts need testing. The xtest extension is already usable, too.

Additionally, ooxcb comes with a simple and powerful event dispatching system (stolen from pyglet) - you don’t have to use it necessarily, but it can make life much easier.

How does it look?

Here’s a minimal example that displays a white window and exits if a mouse button is pressed:

import sys

import ooxcb
from ooxcb.protocol.xproto import *

conn = ooxcb.connect()

screen = conn.setup.roots[conn.pref_screen]
win = Window.create_toplevel_on_screen(conn, screen,
        back_pixel=screen.white_pixel,
        event_mask=EventMask.Exposure | EventMask.ButtonPress
)

with conn.bunch():
    win.configure(width=100)
    win.map()

@win.event
def on_button_press(evt):
    print 'Button pressed, exiting!'
    conn.disconnect()
    sys.exit()

while True:
    try:
        conn.wait_for_event().dispatch()
    except ooxcb.ProtocolException, error:
        print "Protocol error %s received!" % error.__class__.__name__
        break
conn.disconnect()

Is it usable?

As said above, the xproto extension is already wrapped, and ooxcb is relatively stable, so it should be possible to use it (we are already using it for samurai-x). If you stumble upon bugs, please report them on the bug tracker.