Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #53881 > unrolled thread

Monitor key presses in Python?

Back to article view | Back to comp.lang.python

Contents

  Monitor key presses in Python? eamonnrea@gmail.com - 2013-09-09 10:39 -0700
    Re: Monitor key presses in Python? Dave Angel <davea@davea.name> - 2013-09-09 18:19 +0000
    Re: Monitor key presses in Python? John Gordon <gordon@panix.com> - 2013-09-09 18:40 +0000
    Re: Monitor key presses in Python? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-09-09 23:37 +0000
    Re: Monitor key presses in Python? Nobody <nobody@nowhere.com> - 2013-09-10 02:33 +0100
    Re: Monitor key presses in Python? Michael Torrie <torriem@gmail.com> - 2013-09-09 20:43 -0600
    Re: Monitor key presses in Python? Grant Edwards <invalid@invalid.invalid> - 2013-09-10 14:18 +0000
      Re: Monitor key presses in Python? eamonnrea@gmail.com - 2013-09-14 10:44 -0700
        Re: Monitor key presses in Python? Roy Smith <roy@panix.com> - 2013-09-14 14:03 -0400
          Re: Monitor key presses in Python? eamonnrea@gmail.com - 2013-09-14 11:10 -0700
            Re: Monitor key presses in Python? Dave Angel <davea@davea.name> - 2013-09-14 22:03 +0000
        Re: Monitor key presses in Python? Paul Rubin <no.email@nospam.invalid> - 2013-09-14 11:42 -0700

#53881 — Monitor key presses in Python?

Is there a way to detect if the user presses a key in Python that works on most OS's? I've only seen 1 method, and that only works in Python 2.6 and less.  If you get the key, can you store it in a variable?

Also, is there a way to create a callback in Python?

[toc] | [next] | [standalone]

#53882

On 9/9/2013 13:39, eamonnrea@gmail.com wrote:

> Is there a way to detect if the user presses a key in Python that works on most OS's? I've only seen 1 method, and that only works in Python 2.6 and less.  If you get the key, can you store it in a variable?
>
> Also, is there a way to create a callback in Python?

What is usually meant by "a callback" is a function object.  In Python,
functions are first class objects.  You just use the function name
without the parentheses.

def my_function():
    print "Executing my_function"

b = my_function   # b is now a function object

b() 

Likewise, instead of storing it in a global, you might pass it to a
method which stores it as an object attribute, or whatever.

Also of interest is that you can easily create partial functions, where
some of the parameters are already decided.  See the docs for
functools.partial

And if you're trying to use a method as a callback, you can store the
bound-method, which is effectively a partial including the self
parameter.

Finally, don't forget lambda functions, which can be useful if you're
trying to create a simple function and don't need a name for it.


-- 
DaveA

[toc] | [prev] | [next] | [standalone]

#53884

In <57051d11-abd9-4621-9618-1574cd37545c@googlegroups.com> eamonnrea@gmail.com writes:

> Is there a way to detect if the user presses a key in Python that works on
> most OS's?

That depends on what you're really asking; your question is somewhat vague.

Are you asking for a function that waits for the user to press a key and
then returns the key that was pressed?

Or are you asking for a function that detects whether a key has been
pressed at all?

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon@panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"

[toc] | [prev] | [next] | [standalone]

#53892

On Mon, 09 Sep 2013 10:39:43 -0700, eamonnrea wrote:

> Is there a way to detect if the user presses a key in Python that works
> on most OS's? I've only seen 1 method, and that only works in Python 2.6
> and less.

http://code.activestate.com/recipes/577977

I have just tried the above under Linux in Python 3.3, and it works fine. 
I have no way of testing it under Windows.


> If you get the key, can you store it in a variable?

You're new to programming, aren't you? :-)

Yes you can store it in a variable. Anything that is returned can be 
stored in a variable. Here is an example:


py> def example():
...     print("Press any character key... ")
...     c = getch()
...     print("You typed: '%c'" % c)
...
py> example()
Press any character key...
You typed: 'y'


The above is running under Python 3.3.


> Also, is there a way to create a callback in Python?

The answer to your question as you ask it is "Yes, naturally." Callback 
is short for *callback function* and describes the *purpose* of the 
function, not how you write it or what it does. 

But a better answer is, "A callback to what? It depends on what is doing 
the calling back."


-- 
Steven

[toc] | [prev] | [next] | [standalone]

#53897

On Mon, 09 Sep 2013 10:39:43 -0700, eamonnrea wrote:

> Is there a way to detect if the user presses a key in Python that works on
> most OS's? I've only seen 1 method, and that only works in Python 2.6 and
> less.

There's no "generic" solution to this.

At a minimum, there's getting "key presses" from a windowing system and
getting character input from a terminal or console. The two cases are
themselves quite different, and each case has differences between
operating systems.

[toc] | [prev] | [next] | [standalone]

#53899

On 09/09/2013 11:39 AM, eamonnrea@gmail.com wrote:
> Is there a way to detect if the user presses a key in Python that
> works on most OS's? I've only seen 1 method, and that only works in
> Python 2.6 and less.  If you get the key, can you store it in a
> variable?
> 
> Also, is there a way to create a callback in Python?

Some python programs display a graphical user interface.  Others run in
a text-mode console (dos prompt, unix shell, etc).  And yet others don't
have any display at all.  If you're talking about a graphical user
interface app (windows, dialogs, buttons, etc), then you'll have to rely
on the particular user interface library you are using to provide that
sort of access.  If you're just running in a dos box, or a unix
terminal, then there are other ways of doing what you want, but I'm not
sure any one way is portable across all operating systems.  I did find
this code segment that claims to work on windows and unix:

http://code.activestate.com/recipes/134892/

Anyway tell us more about what environment and kind of program you are
dealing with.

As for callbacks, of course.  functions are objects in python.  You can
pass them as arguments, assign them to variables, and then call them.
All graphical user interface libraries rely on them to handle events.

[toc] | [prev] | [next] | [standalone]

#53917

On 2013-09-09, eamonnrea@gmail.com <eamonnrea@gmail.com> wrote:

> Is there a way to detect if the user presses a key in Python that
> works on most OS's?

No.  Unless by "most OSes" you mean "most Unixes" or "most Windows".

> I've only seen 1 method, and that only works in
> Python 2.6 and less.

> If you get the key, can you store it in a variable?

Sure.

> Also, is there a way to create a callback in Python?

Yes.

-- 
Grant Edwards               grant.b.edwards        Yow! I'm having an
                                  at               EMOTIONAL OUTBURST!!  But,
                              gmail.com            uh, WHY is there a WAFFLE
                                                   in my PAJAMA POCKET??

[toc] | [prev] | [next] | [standalone]

#54173

It might sound strange, but I'd need this to run without the user knowing.I believe I can do this by making the file a .pyw file, and use a GUI library to monitor the key presses. I think I could use PyGame, PyGlet and/or Cocos2d as well.

[toc] | [prev] | [next] | [standalone]

#54174

In article <5c59400c-45ca-40f0-846c-05bef3eb0233@googlegroups.com>,
 eamonnrea@gmail.com wrote:

> It might sound strange, but I'd need this to run without the user knowing.

It's called a keylogger.  And after all the revelations about the NSA 
over the past few weeks, it doesn't sound strange at all.

[toc] | [prev] | [next] | [standalone]

#54175

I didnt wanna say that, in case people threw a fit and stuff.

So yeah, how would I monitor the key presses?

[toc] | [prev] | [next] | [standalone]

#54179

On 14/9/2013 14:10, eamonnrea@gmail.com wrote:

> I didnt wanna say that, in case people threw a fit and stuff.
>
> So yeah, how would I monitor the key presses?

There's a huge difference between monitoring key presses within your own
process, and intercepting them system-wide.  if you need to see
keystrokes even when your window does not have the focus, then you need
to call some system DLL function, (some kind of "system hook", which
you can probably do using the platform module, or the ctypes module, or
some module that I wouldn't have on Linux.  This type of code is not the
least bit portable, which just means I can't test things here to try to
help.

Note also that if you get one of the ActivePython implementations from
ActiveState, you'll get PyWin32, which may well have a function just for
the purpose.  See:

http://docs.activestate.com/activepython/2.5/pywin32/PyWin32.HTML

I'm sure it can be separately downloaded, but when I used to run
Windows, I just got the whole package.  The ActivePython also had the
best offline documentation I was able to find at the time.

See also Tim Golden's win32 web page:

http://timgolden.me.uk/python/win32_how_do_i.html

There is a separate win32 mailing list;  see:

https://mail.python.org/mailman/listinfo/python-win32

Possibly the most frequent poster there is Tim Golden, so search his
site first.


-- 
DaveA

[toc] | [prev] | [next] | [standalone]

#54176

eamonnrea@gmail.com writes:
> I'd need this to run without the user knowing.

You are asking for programming advice when you should probably be asking
for legal advice instead, about interception of electronic
communications.  We are not qualified to give legal advice here.

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.python

csiph-web