MouseHook to detect when mouse is moving

Question

I am trying to create a simple mouse hook to detect if the mouse is moving, but for some reason when I run the program, the mouse doesnt function at all until I stop the process.

Here is my code:

#include <windows.h>

HHOOK g_hMouse;

LRESULT CALLBACK MouseHook(int nCode, WPARAM wParam, LPARAM lParam)
{
    printf("MOUSE EVENT!\n");

    return CallNextHookEx(NULL, nCode, wParam, lParam);
}

int main()
{
    g_hMouse = SetWindowsHookEx(WH_MOUSE_LL, MouseHook, NULL, NULL);

    while (1) {
        Sleep(2);
    }

    return 0;
}

Any help would be appreciated.

Thanks.

Answer 1

WM_MOUSE_LL hooks require that the thread that installed it keeps pumping messages; so you'll need a GetMessage/DispatchMessage loop here. Details for this are in the MSDN docs for WM_MOUSE_LL :

This hook is called in the context of the thread that installed it. The call is made by sending a message to the thread that installed the hook. Therefore, the thread that installed the hook must have a message loop.

If you just want to try something quick when experimenting/debugging, replace your Sleep() with a call to MessageBox(...) , which will block your code so you can do testing, but it runs its own message loop, so the hook will run.