GetEventID

PowerBuilder Native Interface

IPBX_VisualObject interface:

GetEventID method

Description

Returns the identifier of an event when the window's parent is notified that the event occurred.

Syntax

GetEventID(HWND hWnd, uint iMsg, WPARAM wParam,   LPARAM lParam)

Argument

Description

hWnd

The handle of the parent window.

iMsg

The message sent to the parent.

wParam

The word parameter of the message.

For WM_COMMAND, the high-order word specifies:

  • The notification code if the message is from a control

  • 1 if the message is from an accelerator

  • 0 if the message is from a menu.

The low-order word specifies the identifier of the control, accelerator, or menu.

For WM_NOTIFY, this parameter contains the identifier of the control sending the message.

lParam

The long parameter of the message.

For WM_COMMAND, this parameter contains the handle of the control sending the message if the message is from a control. Otherwise, this parameter is null.

For WM_NOTIFY, this parameter contains a pointer to a structure.

Return Values

Integer.

Examples

In this 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;
}

Usage

This function is used to process Windows messages, such as WM_COMMAND and WM_NOTIFY, that 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 GetEventID to process these messages.

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. PowerBuilder event token identifiers are mapped to unsigned integer values in the pbevtid.h header file. The identifiers in pbevtid.h are associated with PowerBuilder event token names. For example, the identifier PB_BNCLICKED is associated with the token name pbm_bnclicked.

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

See Also