fullscreen application blocks Windows functions

Hi.
I created a little program in C which is using the keybd_event() and GetAsyncKeyState() function.

The purpose is to create an autowalk macro for a game. The program works perfect on the desktop.

However, if I try to use it in the game (which runs in fullscreen), my program won't work. I guess that's because my program is somehow blocked by the game (maybe because it's demanding all resources, I am not sure why).

How can I make sure my program will work anyway?

I'd be thankful for hints!

Thanks,
moccajoghurt

edit: here's the code:

Code:

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#include <stdio.h>
#include <Windows.h>

int main(void) {
   
    printf("autowalk started. press \"num\" to start and stop.\n");
   
    int pressed = 0;
    int walk = 0;
   
    while (1) {
       
        if (GetAsyncKeyState(144) != 0 && pressed == 0) {
           
            pressed = 1;
           
            if (walk == 0) {
                walk = 1;
            } else {
               
                walk = 0;
            }
           
        } else if (GetAsyncKeyState(144) == 0 && pressed == 1) {
           
            pressed = 0;
        }
       
       
        if (walk == 1) {
            keybd_event(87,0,0,0);
        }
       
        Sleep(10);
    }
}

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You don't use the GetAsyncKeyState() correctly at all.

Firstly, instead of magic numbers use the VK_* provided by Windows.
Secondly, GetAsyncKeyState returns many info about the requested key, in order to find if it is pressed at the current time you do ((GetAsyncKeyState(vkey) & 0x8000) != 0)

It's probably a property of the game. It is not uncommon, in full screen mode, for games to only accept actual keyboard input, and they often achieve that by hooking keyboard handlers (i.e. that gets into the system at a lower level than keybd_event() so effectively disable it from affecting the game). A fair few games do this, precisely to reduce chances of automated cheats, and to force players to actually play.

Conversely, some development tools (eg Silverlight) also disable keyboard input completely in full-screen mode, as a security feature (since full screen applications can be transparent, a full-screen application can do keylogging, while the user thinks they are doing something else).

What exactly is GetAsyncKeyState(vkey) & 0x8000 doing? I have never used the "&" operator that way.

Quote:

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Originally Posted by moccajoghurt

What exactly is GetAsyncKeyState(vkey) & 0x8000 doing? I have never used the "&" operator that way.

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The 16th bit ( or the bit #15 ) indicates whether the key is pressed or not. Set if pressed, clear if not pressed.