How to create a global hotkey?

[k04jg02]

I want to make a Python app that runs in the background, and when a
user hits a key combination, for a function to run. This sounds simple
enough, but all of the keypress detecting libraries I can find count on
you creating a window and then detecting keypresses while that window
has focus. I want my function to execute when the user presses the
hotkey anywhere. I searched the PyGTK documentation and found an old
newsgroup post where someone mentioned the C GTK+ library has it but
PyGTK does not, PyQT showed no results, not sure where else I should
look. I'd be willing to use a library that isn't a windowing toolkit --
I just want to be able to be able to globally detect a keypress. Any
ideas?

 

[Diez B. Roggisch]

I want to make a Python app that runs in the background, and when a
user hits a key combination, for a function to run. This sounds simple
enough, but all of the keypress detecting libraries I can find count on
you creating a window and then detecting keypresses while that window
has focus. I want my function to execute when the user presses the
hotkey anywhere. I searched the PyGTK documentation and found an old
newsgroup post where someone mentioned the C GTK+ library has it but
PyGTK does not, PyQT showed no results, not sure where else I should
look. I'd be willing to use a library that isn't a windowing toolkit --
I just want to be able to be able to globally detect a keypress. Any
ideas?

What OS on? That is the key question here (sorry for the bad pun). It
heavily depends on that, and possibly it hasn't to do with python at all,
but instead configuring e.g. your window manager.

Diez

 

[Gerold Penz]

I want my function to execute when the user presses the

hotkey anywhere.

Hi!

- XLib unter Linux: http://python-xlib.sourceforge.net/
- wxPython unter Windows:
http://wxpython.org/docs/api/wx.Window-class.html#RegisterHotKey

regards,
Gerold


--
________________________________________________________________________
Gerold Penz - bcom - Programmierung
(e-mail address removed) | http://gerold.bcom.at | http://sw3.at
Ehrliche, herzliche Begeisterung ist einer der
wirksamsten Erfolgsfaktoren. Dale Carnegie

 

[dakman]

XLib would really only see the keys pressed when under X, do you want
it to catch the keys directly from the keyboard?

 

[Jordan]

If you're using python 2.4, you can use the pyHook library (I don't
think it has been ported to 2.5 yet... I should email him about that),
which can hook both the mouse and keyboard, so your program can be
running in the background and still catch what keys (or mouse clicks)
are pressed. The pyHook extension comes with some very good examples
of how to use it, but if they aren't good enough examples (I can't
imagine that would happen), you should check out pykeylogger
(sourceforge) which uses the pyHook extension (it's a really good
program. Although not like conventional keyloggers built in C/C++ which
hide themselves from the OS - the purpose was not actually to spy on
the user but to create backups of what was typed - it still does a very
good job and the latest release has a lot of options and
extendability). If your OS is linux, unix, or mac... good luck ;D

Cheers,
Jordan

 

[k04jg02]

Sorry, I should have mentioned that I'm running Linux, and I only will
be running this app while X is running. pyHook doesn't seem to be an
option because it's win32 only. I'm guessing python-xlib is the way to
go, but it seems to be that it relies on you understanding the C xlib
library, which is old and heavily obfuscated. Any advice on how to use
python xlib to register a global hotkey? In the docs I found the
KeyEvent event type, but it seems to want a specific window too.

 

[Paul Boddie]

Sorry, I should have mentioned that I'm running Linux, and I only will
be running this app while X is running.

Global "hot keys" are typically the domain of the desktop environment
(or window manager for archaic desktops). For example, KDE has a
configuration dialogue where you can define hot keys or key
combinations that do particular things: I've got the Windows key doing
useful stuff in combination with other keys, for example.

So programmatically setting hot keys may be something that requires
communication with the desktop environment, and it would appear that on
KDE you have to put hot key definitions in a file and then import them,
the latter possibly being achieved using the DCOP interprocess
communications mechanism provided in the environment (try "dcop
khotkeys khotkeys" at the shell). Here's the only documentation I've
found so far:

http://developer.kde.org/~seli/khotkeys/

I suppose you could just plug in at the X level and have something
define and intercept a hot key before the desktop environment has a
chance to process it, but I doubt that this would be a particularly
nice solution.

Paul

 

[k04jg02]

Global "hot keys" are typically the domain of the desktop environment
(or window manager for archaic desktops).

Yep, that's why my first thought was to use PyQT or PyGTK.
Unfortunately neither seems to have the ability.

So programmatically setting hot keys may be something that requires
communication with the desktop environment, and it would appear that on
KDE you have to put hot key definitions in a file and then import them,
the latter possibly being achieved using the DCOP interprocess
communications mechanism provided in the environment (try "dcop
khotkeys khotkeys" at the shell).

This is really annoying to setup and would be a KDE specific solution.
Ideally this would work under Gnome or KDE. Applications do this all
the time -- Amarok for example adds global shortcuts for playing,
pausing, jumping to next track, etc. that work whether or not you're in
KDE or Gnome.

I suppose you could just plug in at the X level and have something
define and intercept a hot key before the desktop environment has a
chance to process it, but I doubt that this would be a particularly
nice solution.

Why not? If I had to guess at this point I'd say it's the 'right' way
to do it. I'm going to be dealing with keypresses that no other apps or
the desktop environments have bound to anything, so I'm not sure it
really qualifies as 'intercepting'. If multiple apps have registered to
receive global keypresses, and the first app that looks at a keypress
doesn't know how to handle it, shouldn't it just get passed on to the
next app?

 

[Jonathan Curran]

I want to make a Python app that runs in the background, and when a
user hits a key combination, for a function to run. This sounds simple
enough, but all of the keypress detecting libraries I can find count on
you creating a window and then detecting keypresses while that window
has focus. I want my function to execute when the user presses the
hotkey anywhere. I searched the PyGTK documentation and found an old
newsgroup post where someone mentioned the C GTK+ library has it but
PyGTK does not, PyQT showed no results, not sure where else I should
look. I'd be willing to use a library that isn't a windowing toolkit --
I just want to be able to be able to globally detect a keypress. Any
ideas?

A little bit of googling revealed:

XGrabKey: http://tronche.com/gui/x/xlib/input/XGrabKey.html
Example: http://tigerdyr.wheel.dk/ctwm-archive/1328.html

It's done here in C, hopefully you can do the same with the python module for
xlib that was mentioned earlier.

- Jonathan

Google = best friend

 

[Paul Boddie]

Paul Boddie wrote:
[DCOP]

This is really annoying to setup and would be a KDE specific solution.

Searching for "PyKDE global shortcut" produced something at the PyQt
level:

http://lists.kde.org/?l=pykde&m=115451566321878&w=2

I don't know whether that is useful in this context, however.

Ideally this would work under Gnome or KDE. Applications do this all
the time -- Amarok for example adds global shortcuts for playing,
pausing, jumping to next track, etc. that work whether or not you're in
KDE or Gnome.

The source code for Amarok is available, so if you're not afraid of
looking at C++ code there may be an answer somewhere in there.

Why not? If I had to guess at this point I'd say it's the 'right' way
to do it. I'm going to be dealing with keypresses that no other apps or
the desktop environments have bound to anything, so I'm not sure it
really qualifies as 'intercepting'. If multiple apps have registered to
receive global keypresses, and the first app that looks at a keypress
doesn't know how to handle it, shouldn't it just get passed on to the
next app?

I'm not that familiar with the event model involved, but one
disadvantage of handling things at the X level is that people may not
be able to inspect or override any shortcuts or hot keys that your
application defines within their desktop environment's configuration
dialogues. That's why it may be best going through the desktop
environment, even though that might mean dealing with different
mechanisms in different cases.

Unfortunately, the freedesktop.org people haven't introduced standards
for global shortcuts, as far as I can tell. Here are some documents I
found (by searching for "global shortcut freedesktop standard"):

http://www.freedesktop.org/wiki/Standards_2fdefault_2dkeys_2dspec
http://portland.freedesktop.org/wiki/IntegrationTasks

Paul