PRB: MFC ActiveX Control in IE Doesn't Detect Keystrokes

RESOLUTION

Here is a typical PreTranslateMessage. This code forwards ARROW, HOME, and END keys back to the control so that they can be received using a MESSAGE_MAP entry:

   // trap keys and forward on to the control
   BOOL CMyActiveXCtrl::PreTranslateMessage(MSG* pMsg)
   {
      switch (pMsg->message)
      {
         case WM_KEYDOWN:
         case WM_KEYUP:
            switch (pMsg->wParam)
            {
               case VK_UP:
               case VK_DOWN:
               case VK_LEFT:
               case VK_RIGHT:
               case VK_HOME:
               case VK_END:
                  SendMessage (pMsg->message, pMsg->wParam, pMsg->lParam);
                  // Windowless controls won't be able to call SendMessage.
                  // Instead, just respond to the message here.
                  return TRUE;
            }
            break;
      }
      return COleControl::PreTranslateMessage(pMsg);
   }
				

If you have a child control within your ActiveX control, you need to UI-Activate the whole control whenever that child control is activated. For example, if you have an edit control inside your ActiveX control, add a handler as follows to your ActiveX control class:

   int CMyActiveXCtrl::OnMouseActivate(CWnd* pDesktopWnd, UINT nHitTest, UINT
   message)
   {
      if (!m_bUIActive)
          OnActivateInPlace (TRUE, NULL); // == UI-Activate the control
      return COleControl::OnMouseActivate(pDesktopWnd, nHitTest, message);
   }
				

Because Internet Explorer may not immediately UI-Activate a control, even if that is the only control on the page, it may be desirable to automatically request a UI-Activation when the control is created. This can be done during the COleControl::OnCreate (WM_CREATE) handler. Windowless controls do not get WM_CREATE or any windows messages; therefore, this code won't work in a windowless control. Also note that this does not guarantee that a control will remain UI-Activated. If there are other controls on a page that request UI-Activation in a similar manner, only one will eventually be UI-Activated and receive keystroke messages as described. And if the user TABs away from an ActiveX Control, Internet Explorer will automatically UI-deactivate the control.

   int CMyActiveXCtrl::OnCreate(LPCREATESTRUCT lpCreateStruct)
   {
      if (COleControl::OnCreate(lpCreateStruct) == -1)
         return -1;
      OnActivateInPlace (TRUE, NULL); // == UI-Activate the control
      return 0;
   }