An incomplete xcb-util port plus some extras
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README.md
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README.md

Introduction

xpybutil is an abstraction over the X Python Binding (xpyb - the Python version of XCB). It exists because xpyb is a very low level library that communicates with X.

The most mature portions of xpybutil are the ICCCM and EWMH modules. Each implement their respective specifications of the same name. The EWMH module also implements the '_NET_WM_WINDOW_OPACITY' and '_NET_VISIBLE_DESKTOPS' non-standard features. The former is widely used by compositing managers and other utilities (i.e., xcompmgr and transset-df) while the latter is used by my fork of Openbox called Openbox Multihead.

Examples

There are a few examples included in the 'examples' directory of the source of xpybutil. You could also look at my 'window-marker' or 'pytyle3' utilities. The former is a small script but the latter is on the order of ~1000 lines and encompasses a wide variety of use cases of xpybutil. (And still yet, other use cases are probably more appropriate only for window manager development.)

Another program that uses xpybutil is 'pager-multihead'. I would advise not looking to it for inspiration, as it mixes xpybutil and GTK. (Namely, it uses GTK's event dispatcher, but interacts with the window manager mostly using xpybutil.)

Usable modules

cursor.py - Provides a listing of all built-in X cursors, and provides a function 'create_font_cursor' to create one. This object can then be directly used in a call to CreateWindow or ChangeWindowAttributes.

ewmh.py - A module that implements the entire EWMH spec.

event.py - A module that can send client events to windows. It also allows registering callback functions to particular events. It can also run the main event loop.

icccm.py - A module that implements most of the ICCCM spec.

image.py - An incomplete and haphazard collection of functions that can bridge a gap between PIL and drawing images with X.

keybind.py - A set of functions devoted to binding key presses and registering callbacks. This will automatically hook into the event callbacks in event.py.

keysymdef.py - The sole purpose of this module is to provide a mapping from X keysyms to english string representations (for easier binding by the user). This should probably never be used directly. It is used by the keysym module.

motif.py - Implements a subset of the Motif spec. This module exists because some window managers still use this as the only way of toggling window decorations via events.

mousebind.py - Similar to keybind.py, but for mice.

rect.py - A few utility functions that do math associated with X style rectangles. (i.e., a 4-tuple of (top_left_x, top_left_y, width, height).) It can also calculate monitor rectangles after accounting for struts.

render.py - A nearly exact port of the module by the same name from xcb-util. I used it once to help with a compositing manager that I wrote with xpyb.

util.py - A vast assortment of utility functions. The ones of interest to you are probably 'get_atom' and 'get_atom_name'. The rest are heavily used throughout the rest of xpybutil.

window.py - A few utility functions related to client windows. In particular, getting an accurate geometry of a client window including the decorations (this can vary with the window manager). Also, a functon to move and/or resize a window accurately by the top-left corner. (Also can change based on the currently running window manager.)

           This module also contains a function 'listen' that must be used
           in order to receive certain events from a window. For example,
           if you wanted to run 'func' whenever a property on the root
           window changed, you could do something like:

           import xpybutil
           import xpybutil.event as event
           import xpybutil.ewmh as ewmh
           import xpybutil.util as util
           import xpybutil.window as window

           def func(e):
             if util.get_atom_name(e.atom) == '_NET_ACTIVE_WINDOW':
               # Do something whenever the active window changes
               active_window_id = ewmh.get_active_window().reply()

           window.listen(xpybutil.root, 'PropertyChange')
           event.connect('PropertyNotify', xpybutil.root, func)

           The idea here is to tell X that you want events that fall under
           the 'PropertyChange' category. Then you bind 'func' to the
           particular event 'PropertyNotify'.

xinerama.py - A couple of functions that support retrieving information about all active physical heads. This is done through the Xinerama extension, which implicitly supports RandR and TwinView.

           The 'get_physical_mapping' function will produce a list of
           monitor indices in a physical ordering (left to right, top to
           bottom). These indices can then be used in the list returned by
           'get_monitors'.

Unusable modules

font.py is pretty inadequate. Mostly because if you find yourself wanting to use font.py, you're probably doing something wrong. (i.e., use pycairo or PIL.)

EWMH and ICCCM

xpybutil's primary purpose was to make accessing ICCCM and EWMH related information extremely easy. This can be done by using the ewmh or icccm modules. Here's a quick example (assuming xpybutil is installed):

import xpybutil.ewmh as ewmh

desktop_names = ewmh.get_desktop_names().reply() current_desktop = ewmh.get_current_desktop().reply()

print names.get(current_desktop, current_desktop)

This imports the ewmh module (and by extension, connects to the X server) and fetches a list of the current desktop names and the current desktop index (starting from 0). Since not every desktop must be named, the desktop index is printed if it has no name.

Note that the functions in the ewmh and icccm module return cookies. In order to pull a response from the X server, call the 'reply()' method on a cookie object. To force a response sent to the X server, call the 'check()' method on the corresponding cookie.

Much of the EWMH and ICCCM modules encapsulate packing data from convenient Python data types into C structs (using the 'struct' Python module). For example, if one wants to fetch the partial struts set by some window with identifier ID, you could do:

import xpybutil.ewmh as ewmh

print ewmh.get_wm_strut_partial(ID).reply()

Which outputs a dictionary with 12 entries, where each corresponds to a value in the partial strut. (i.e., 'left', 'top_end_x', 'right_start_y', etc...).

In general, particularly with the EWMH module, the ewmh module is very nearly representative of the spec itself. Functions that get property values start with 'get_', functions that set property values start with 'set_', and functions that send an event to a client (which typically requests the window manager to DO something) start with 'request_'.

If a request has no reply (typically the 'set_' functions), then the default is to call it 'unchecked'. If you want to check the result (and force retrieval), then use the '_checked' variant.

The reverse goes for the 'get_' functions. By default, they are checked, but you can use the '_unchecked' variant too.

Basically, you should probably almost always use the 'checked' variant of everything. The cases where you don't are when you want to send a whole bunch of requests to the X server at once. You could use the unchecked invariant, and after you've initialized all the cookies, calling 'flush' will force communication with the X server.

Finally, unless you're writing a window manager or creating a client window from scratch, you'll almost always want to use the 'get_' and 'request_' functions, not 'set_'. For example, if you want to change the current desktop...

DON'T DO: ewmh.set_current_desktop_checked(2).check()

DO: ewmh.request_current_desktop_checked(2).check()

The former will probably not work, but the latter will. Just follow the EWMH spec :-)