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.
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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; } |