WTL is the best library for Win32 Programming I have seen, simple and powerful. But sometimes during a period of time I have to change my mind and work with other libraries and tools, and then I forget some basic ATL/WTL concepts like:
- Event Sink implementations
- ActiveX instancing
- Other basic hard-to-forget concepts
For this reason I'm developing a little library in a WTL like fashion that will help me, (and maybe someone out there), to make my life easier with WTL.
This class and other related classes in this article will help you to make your job with ActiveX controls easier.
CWTLAxControl is a class that implements :
- SmartPointer (
Maybe it seems to be a hard class to use , but wait a minute and take a look at the next
IExplorer implementation, using this class you will have access to the
IWebBrowser2 methods interface via "->" ( smart pointer ), window messages handling (Host window) and Sink Events events fired from ActiveX hosted to your own event handlers.
#define EVENTFN void __stdcall
class CWTLIExplorer : public CWTLAxControl<CWTLIExplorer,IWebBrowser2>
BEGIN_MSG_MAP( CWTLIExplorer )
LRESULT OnCreate(UINT uMsg, WPARAM wParam , LPARAM lParam,
uMsg, wParam, lParam, bHandled );
BEGIN_SINK_MAP( CWTLIExplorer )
SINK_ENTRY(0, DISPID_NAVIGATECOMPLETE2, OnNavigateComplete2 )
EVENTFN OnNavigateComplete2( IDispatch* pDisp, VARIANT* URL )
MessageBox( "OnNavigateComplete2" );
Well, if you like the above implementation then it is time to get a more detailed view of how it works.
The first step is to take a look into the main parent class
CWTLAxControl that looks like:
template <class T, class Interface>
class CWTLAxControl : public CComPtr<Interface>,
LRESULT OnCreate( UINT uMsg, WPARAM wParam , LPARAM lParam,
BOOL & bHandled )
lRet = DefWindowProc( uMsg, wParam,lParam );
HRESULT AttachControl( BOOL bWithEvents = false )
HRESULT hr = S_OK;
hr |= AtlAxGetControl( m_hWnd, &spUnk);
hr |= spUnk->QueryInterface( __uuidof(Interface),
if ( bWithEvents && ! FAILED(hr) )
hr|= EasyAdvise( spUnk );
This class helps us to attach our
CComPtr to the ActiveX control using the
AttachControl method when it receives the
WM_CREATE message. Furthermore this class is derived from
CWindowImpl that give us the chance to handle all the windows messages that we'll need.
The last class
CWTLDispEventHelper will help us to setup the correct
This class will help us to setup the Event Sink for our control and looks like:
template <class T,class Interface>
class CWTLDispEventHelper : public IDispEventImpl<0,T>
HRESULT EasyAdvise(IUnknown* pUnk)
m_pUnk = pUnk;
return DispEventAdvise(pUnk, &m_iid);
&m_iid, &m_wMajorVerNum, &m_wMinorVerNum);
return DispEventUnadvise(pUnk, &m_iid);
It has only two methods
to setup the Event Sink handler and
to deactivate it.
How to create the Control
Well, this is the easiest thing, the normal way we use to create any window in WTL:
m_pBrowser.Create( m_hWnd, rcDefault, _T("about:blank"),
WS_HSCROLL| WS_VSCROLL| WS_CHILD | WS_VISIBLE |
WS_CLIPSIBLINGS | WS_CLIPCHILDREN );
We can change the
_T("about:blank") by the CLSID of the control we want to create
Well, I expect you will find this article useful and helpful for you, if this is the case and you find anything wrong here, please, send me an email and I will be very happy to solve the mistake and re-upload this article. Bye!
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