Question

In my keyboard hook, each keypress gets a flag that states if it was injected or not.
http://msdn.microsoft.com/en-us/library/ms644967(VS.85).aspx

I’ve distilled a KBDLLHOOKSTRUCT from the lParam. I can access kbd.flags.XXX. I just don’t know how to convert this 8bit flag into an if (injected) {... type conditional that I know how to use.

If one of you smart computer-science types would help me out I’d really appreciate it.

    private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
    {
        KBDLLHOOKSTRUCT kbd = new KBDLLHOOKSTRUCT();
        Marshal.PtrToStructure(lParam, kbd);

        //if (injected) {...

Cheers!

Answer 1

You need to bitwise-and it with a mask. For example, the injected bit is bit 4. That’s binary 00010000, hex 0x10. So you bitwise-and it with 0x10, and see if anything’s left:

bool isInjected = ((kbd.flags & 0x10) != 0);

(Of course, as per Andrew’s answer, it would be a good idea to define a LLKHF_INJECTED constant for this rather than including the hex value directly in your code!)