cannot trap VK_RETURN key for subclassed editbox control.

Question

I subclassed an edit box control like

lpfnOldWndProc = (FARPROC)SetWindowLong(hEdit,GWL_WNDPROC, (DWORD)SubClassFunc);




LRESULT FAR PASCAL SubClassFunc(   HWND hWnd,
           UINT Message,
           WPARAM wParam,
           LPARAM lParam)
{

    switch(Message)
    {

    case WM_CHAR:
     //Process this message to avoid message beeps.
     if ((wParam == VK_RETURN) || (wParam == VK_TAB))
     {
      //Do Something
      return 0;
     }

     break;
    case WM_KEYDOWN:
     if ((wParam == VK_RETURN) || (wParam == VK_TAB)) {
      //Do Something
      return 0;
     }

     break ;

    default:
     break;
    }

    return CallWindowProc((WNDPROC)lpfnOldWndProc, hWnd, Message, wParam, lParam);

}

Now when I enter char in editbox this subclassed procedure gets called. But I am not able to get it when enter key is pressed.

Is this something wrong in above procedure.

Answer 1

No, the system uses WM_GETDLGCODE to determine which key presses the control is interested in. By default a edit box doesn't process Return (the dialog procedure interprets it as pressing the default button) and therefore doesn't require that VK_RETURNS are sent to it. You need to process the WM_GETDLGCODE message and return DLGC_WANTALLKEYS then you should get your VK_RETURNS.

The MS documentation outlines this sub-classing scenario pretty well.