Direct access to the keyboard?

Question

Hi all -
I'm having some trouble because I'm making an application that I want to run on all platforms. I'm creating it on OS X, but I want to have it run on Linux as well.
The problem, which I'm sure at least some of you are aware, is that in Linux (at least in KDE) the 'key repeat' function triggers 'key released' events as well as 'key pressed' events even when the user is holding down the key. This makes it very hard to do (seemingly) simple things like determine how long the user has been holding down a key.
I'm aware of some of the work arounds, so lets just get that out of the way:
1. Turn off 'key repeat'. That just isn't realistic if you want to make a commercial application you can't expect users to be changing their system settings to just run your application when they don't have to for any other application. C++ people would make fun of me ;)
2. Use a timer to figure out if the last 'key released' event was a real one. This doesn't work because it is hard to know what value the user has their key repeat set to, you don't know if the user is holding down the key or pressing it rapidly, and it adds extra overhead for OS's that don't have this problem.
3. Post the event to your internal actions and then consume it. Again, no way to tell if the user is holding down the key or not and you are somewhat dependant on the key repeat being very rapid.
So I figure that if I can at least just get an array or something of the current state of the keyboard, then I can figure all this out for myself. I'm asking this in the 'games' section because I know this is a common way to do games programming (in DirectX for example). I've looked at some of the Xith3D and similar boards, but everyone there seems to be happy with one of the previously mentioned solutions.
Is there a real solution to this? ...or if not, can I at least look at the key state myself and just deal with it on my own?
Thanks!

Answer 1

Thanks, Luther.
That solution works well on Linux, but fails on Mac OS X. (Have not tested on Windows).
I can't believe there's no way to do something as basic as actually knowing when the user has a key pressed down! This seems like a pretty big hole, and I imagine there must be some real workaround somewhere...
Here's another hack, but it only works in video games, etc., where you have a separate thread running (and SOMETIMES it may still fail due to synchronization issues):
http://forums.dreamincode.net/showtopic14233.htm
My solution, which may or may not work on any given OS, but worked when tested on Linux and Mac OS X:
          long lastUpTime=0;
          char lastUpChar='a';
               public void keyPressed(KeyEvent e) {
                    System.out.println("lastUpTime="+lastUpTime);
                    // it's zero under linux, it's <6 for Mac OS, so we just use 10ms tolerance
                    if (lastUpTime-e.getWhen()<10 && lastUpChar==e.getKeyChar()) {
                         System.out.println(" think it was FAKE released");
                         lastUpTime = 0;
                         lastUpChar='a';
                         return;
                    } else if (lastUpTime!=0) {
                         // okay, the key was released. log at that time.
                         System.out.println("Key released: \""+lastUpChar+"\" a while ago, at "+lastUpTime);
                         lastUpChar='a';
                         lastUpTime=0;
                         return;
                    System.out.println("Key pressed: "+e.getKeyChar());
                    lastUpTime=0;
                    lastUpChar='a';
               public void keyReleased(KeyEvent e) {
                    if (e.getKeyChar()==' ' || e.getKeyChar()=='b') {
                         System.out.println("Tentative key realeased: "+e.getKeyChar());
                         lastUpTime=e.getWhen();
                         lastUpChar=e.getKeyChar();
               }});