Re: key press events & holding keys down

[Stefan Skoglund <Stefan Skoglund agj net>]

mÃn 2012-03-19 klockan 13:37 -0800 skrev Christopher Howard:
> So, you mean, receive both key press and key release events, and then
> maintain my own tracking of whether or not the key is currently being
> held down? Okay, that makes sense to me, provided of course I can be
> certain that all key press and key release events are properly reported
> to my program (otherwise my internal state my gets screwed) and in the
> correct order.
>
> However, the approach I was hoping for, i.e. simply checking the current
> "reality" state of a key (whether it is actually pressed down or not)
> sounds more convenient. If anyone could tell me how to do that, I would
> be grateful.

Which you can't, key events (all events ?) in X11 is edge triggered.

> BTW, in the ClanLib program I did something like so:
>
> code:
> ----------
> // initialize keyboard object
> CL_InputDevice keyboard = window.get_ic().get_keyboard();
>
> // ...snip...
>
> // start main loop
>
> /* get_keycode() would check if that key was currently depressed
>    Obviously, not a very practical approach for word processing
>    or typing into a text box, but simple and quite appropriate
>    in, say, a space combat game
> */
> if(keyboard.get_keycode(49)) // do something

You should understand that the way to deal with events in Gdk is decided
by how X11 deals with for example key events.

You should pick up the key_down event and key_release event but you
should also pick up the enter_focus and leave_focus events (window
looses keyboard focus = window won't get any key events.)

The program should get a consistent view of keyboard key state if the
program as such is prepared to deal with the focus events.