Processing events sent to the parent of the window

Processing events sent to the parent of the window

Some Windows messages, such as WM_COMMAND and WM_NOTIFY, are sent to the parent of an object and not to the object itself. Such messages cannot be caught in the visual extension's window procedure. The PBVM calls the GetEventID method to process these messages, as follows:

• If the message is mapped to a PowerBuilder event, GetEventID returns the event's identifier, for example PB_BNCLICKED, and the event is fired automatically.

• If the message is not mapped to an event, GetEventID returns the value PB_NULL and the message is discarded.

In the following example, the GetEventID function returns the identifier PB_BNCLICKED if a WM_COMMAND message with the notification code BN_CLICKED was sent. It returns the identifier PB_ENCHANGE if a WM_NOTIFY message was sent. Otherwise, it returns PB_NULL.

TCHAR CVisualExt::s_className[] = "PBVisualExt";
 
LPCTSTR CVisualExt::GetWindowClassName()
{
  return s_className;
}
 
HWND CVisualExt::CreateControl
(
  DWORD dwExStyle,      // extended window style
  LPCTSTR lpWindowName, // window name
  DWORD dwStyle,        // window style
  int x,               // horizontal position of window
  int y,            // vertical position of window
  int nWidth,       // window width
  int nHeight,      // window height
  HWND hWndParent,  // handle of parent or owner window
  HINSTANCE hInstance // handle of application instance
)
{
  d_hwnd = CreateWindowEx(dwExStyle, s_className,
    lpWindowName, dwStyle, x, y, nWidth, nHeight,
    hWndParent, NULL, hInstance, NULL);
 
  ::SetWindowLong(d_hwnd, GWL_USERDATA, (LONG)this);
 
  return d_hwnd;
}
 
int CVisualExt::GetEventID(
   HWND    hWnd,     /* Handle of parent window */
   UINT    iMsg,     /* Message sent to parent window*/
   WPARAM  wParam,   /* Word parameter of message*/
   LPARAM  lParam    /* Long parameter of message*/
  )
{
  if (iMsg == WM_COMMAND)
  {
    if ((HWND)lParam == d_hwnd)
    {
      switch(HIWORD(wParam))
      {
      case BN_CLICKED:
        return PB_BNCLICKED;
        break;
      }
    }
  }
 
  if (iMsg == WM_NOTIFY)
  {
    return PB_ENCHANGE;
  }
  return PB_NULL;
}