Thread: GetKeyboardState() problem

I can't give an example, but more importanly, it would not help much if I give an example that tries to do something completely different from what you want it to do...

I meain, the function itself is pretty simple:

Code:

#include <windows.h>
int main()
{
   BYTE keyState[256];

   ... Do something for a bit. 
   if ( GetKeyboardState( keyState ) )
   {
      ... Use keystate[] to find out which key(s) were pressed.
   }
   else
      ... print error message. 
   }
   return 0;
}

You may want to read this

Originally Posted by MSDN

The status changes as a thread removes keyboard messages from its message queue. The status does not change as keyboard messages are posted to the thread's message queue, nor does it change as keyboard messages are posted to or retrieved from message queues of other threads. (Exception: Threads that are connected through AttachThreadInput share the same keyboard state.)

I think that may be source of your problems.

--
Mats

If you read the quoted text, I think you will find that it says "As the thread removes keyboard messages from the message queue" (my hand-quoting, typing it in, so it may be slightly misworded - read the original quote in the post above). In your example, it does not read the message queue, so VK_ESCAPE will never get set [unless it already was before the loop].

--
Mats

Originally Posted by hauzer

Yes, I know that but my problem is how to check if a key is pressed/toggled.

Check for KB messages in your message loop.

Or, perhaps, use DirectInput or GetAsyncKeyState.

It all depends on what you ACTUALLY want to do, how often you plan on checking, etc, etc.

Which is why I said "It doesn't matter if I give an example if it does something completely different from what you want to do".

Explain what your application is actually doing [or what you WANT it to do], and we may be able to give better advice. There are several different solutions, all depending on what you are doing and what the rest of the code is doing.

Edit: And I consider it rather rude to remove the post that I just commented on - yes, it contained code that would never work based on the quote I gave - but it would:
1. Make my post make sense to other readers.
2. Serve as an example of "how not to do it".
[Yes, I could have avoided looking like a fool that comment on my own posts by quoting your original post - but you could also have just edited the post to say "Sorry, I realize the above code won't work" after you read my post].

--
Mats

Originally Posted by lruc

While were on the subject of keyboard input, what exactly is the error with GetAsyncKeyState()? I have heard a few times that something is wrong with it.

Provide some context - what error are we talking of? This was requested in the previous thread where you mentioned this problem too. I'm not aware of any "it's so broken you can't possibly use it", but of course, it is an asynchronous interface. If you ask me what time it is, and I say "quarter past three last time I checked", does that actually mean that it IS quarter past three? No, of course not, it's right now (where I am) 15.56, so four minutes to four. Same with GetAsyncKeyState - it provides a snapshot of what the keystate for that key is at the time of asking. If the user presses the key 1 microsecond after you asked, then it's not pressed when you ask. If the user released the key 1 microsecond before you asked, it is not pressed.

--
Mats