CODEWITHSUNDEEP
cwindows
Serinice
Serinice

Reputation: 138

Wait for a keypress in an application with no console or window

I need a way to get a keypress from an application which has no console or GUI windows. I'm currently polling using GetAsyncKeyState but this uses unnecessary amounts of CPU time.

Is there a better solution?

Note: Since the application does not have a console, I cannot use getchar or other such console only functions.

Upvotes: 0

Views: 134

Answers (1)

WalterM
WalterM

Reputation: 2706

This is a low level hook so it receive events from the kernel. That means you will receive these events even if it's for another application.

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

LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam){
    KBDLLHOOKSTRUCT *kbd = (KBDLLHOOKSTRUCT*)lParam;
    switch(nCode){
        case HC_ACTION:
            switch(wParam){
                case WM_KEYUP:
                case WM_KEYDOWN:
                    printf("[%i %s %c]\r\n", kbd->time,
                            wParam == WM_KEYUP ? "Up" : "Down",
                            kbd->vkCode);
                    break;
            }
            break;
    }
    return CallNextHookEx(0, nCode, wParam, lParam);
}

int main(int argc, char** argv) {
    HHOOK kbdHook = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, 0, 0);
    MSG msg;
    while (GetMessage(&msg, 0, 0, 0)) {

    }
    UnhookWindowsHookEx(kbdHook);
    return 1;
}

Upvotes: 3

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