Thread: Doing stuff when certain Key combo's pushed

I'm sure this is easy for someone, so here goes. I have a dialog based app that accepts use input. When a user hits something like alt and 2 at the same time, I want to change all the text to * or something. How do I check for the key combo being pressed?
-HisWord

Well, alt + combiantions are easy, because there's a special message sent when a key is pressed with ALT.

That is the WM_SYSKEYDOWN message -- you could trap this, or trap WM_SYSCHAR, and if the character is '2' then do what you want to do.

That looks like it should do something, both when you press ALT+f1, and when you release it.

Are you sure that the window you're using has the keyboard focus? In some programs, it can be tricky to know which has focus, in cases where your main window is a frame window, and the window you are interacting with is its client window. In this case, the client window will get the messages.

I'm attaching some of my own code, this DOES work. I hope it helps.

Code:

 switch (msg)
    {
        // other nonrelevant stuff removed for clarity
       case WM_SYSKEYDOWN:
            if (wParam == 'F') s.showFPS = !s.showFPS;
        case WM_KEYDOWN:
            // Handle any non-alt combo key commands
            switch (wParam)
            {
                case VK_F1:
                    PlaySound("audio\\hailduke.aud", 0, SND_ASYNC |  SND_NODEFAULT| SND_FILENAME);
                    break;
                case VK_F2:
                    MIDI->Play("audio\\theme.mus");
                    break;
                case VK_F3:
                    MIDI->Play("audio\\loop.mus",true);
                    break;
                case VK_F4:
                    MIDI->Stop();
                    PlaySound("",0,SND_ASYNC);
                    break;
                case VK_F12:
                    absolutelyUpdate = true;
                    break;
                case VK_SPACE:
                    spaceIsDown = true;
                    break;
            }
            break;
        case WM_SYSKEYUP:
        case WM_KEYUP:
            //handle key release commands
            switch(wParam){
                case VK_SPACE:
                     spaceIsDown = false;
                     break;
                case VK_F12:
                		absolutelyUpdate = false;
                     break;
            }
            break;
}

Crap, it messed up some of the tabs, but it still looks readable.

This, in a nutshell, does the following:

F1 plays a WAV, F2 and F3 play MIDIs. F4 stops playback. The program tracks whether the spacebar is down or up, and when the alt+f combo is pressed, it toggles showing or hiding FPS. As long as f12 is down, it forces total screen redraws ever 1/30th of a second.

This code was basically done to provide a quick means of testing various things (tests MIDIs, WAVs, and forced screen redraw vs. "intelligent" screen redraw).

Funny you ask. I had the same problem a while back. Try this:
PreTranslateMessage is a virtual function that you must add trough the class wizard. This works I just tried it.


BOOL CMyDialog::PreTranslateMessage(MSG* pMsg)
{
if(pMsg->message == WM_KEYDOWN)
{
//do this or the other

MessageBox("Aha!");

return TRUE;

}

return CDialog::PreTranslateMessage(pMsg);
}

Well, a dialog IS a window. It's a style of window, but anything which works on a generic window will work on it.

You're using the Borland compiler -- are you using OWL (is this even supported for the free compiler?) or are you using WinAPI command to create/handle windows?