Re: Hooking into the input queue(?)

["Brian J. Tarricone" <bjt23 cornell edu>]

On 12/02/04 15:16, Jan wrote:
> Tristan Van Berkom wrote:
> > On Thu, 02 Dec 2004 14:15:06 +0000, Jan <jandersen informatica com> wrote:
> > [...]
> > > I know that in the earlier versions of Windows an application could hook
> > > in to different places in the system, among others the keyboard message
> > > queue, and I assume this is what the producers of this game did. How
> > > would one do the same in Gnome?
> >
> > I think you are looking for something like this:
> > http://developer.gnome.org/doc/API/2.0/gtk/gtk-General.html#gtk-key-snooper-install
> >
> > The prerequisite is that the application in question has to have keyboard 
> > forcus
> > somewhere (i.e. the keyboard snooper approach lets you get key input events
> > that are delivered to your application before they get delivered to
> > particular widgets
> > such as text entries etc.)
> >
> > I think that to get "global" key input then you have to fool around with
> > the terminal that X is running in and kind of tee the output, there might 
> > be
> > some kind of inittab entry for that or something.
> Yes, it is this global approach I am after - it has to be possible 
> somehow. I assume the X server is the one that captures the physical 
> keystrokes and sends them to - the window manager? Or directly to the 
> application?

there's a draft spec for an X extension out, called the X Event Interception
Extension.  it's listed on freedesktop:
http://freedesktop.org/Standards
unfortunately, the link appears to be broken.  i don't know if there's a
working implementation of this.

i know the WM is capable of getting all keyboard events, as some WMs 
implement global keybindings that way.  last time i tried calling
XSelectInput() on the root window to get KeyPress events, my app quit with
a BadMatch error.  hmmph.  so, hacking your favorite WM might do the trick,
though this may not be the kind of effort you were looking for.

        -brian