ArcGIS Engine Developer Guide

VISUAL C++
Make sure dialog boxes that host ActiveX
controls inherit from CAxDialogImpl and not
CDialogImpl. If this mistake is made, the
DoModal method of the dialog box simply exits
with no obvious cause.
Make sure applications that use windows
common controls, such as treeview, correctly call
InitCommonControlsEx to load the window
class. Otherwise, the class will not function
correctly.
Make sure applications using COM objects call
CoInitialize. This initializes COM in the
application. Without this call, any CoCreate calls
will fail.
For a detailed discussion on handling events in
ATL, see the later section ‘Handling COM events
in ATL’.
Accessing a control on a dialog box through a COM interface
To retrieve a handle to the control that is hosted on a form, use the GetDlgControl
ATL method that is inherited from CAxDialogImpl to take a resource ID and
return the underlying control pointer:
ITOCControlPtr ipTOCControl;
GetDlgControl(IDC_TOCCONTROL1, IID_ITOCControl, (void**) &ipTOCControl);
ipTOCControl->AboutBox();
Listening to events from a control
The simplest way to add events is to use the class wizard. Right-click the control
and choose Events. Next, click the resource ID of the control, then click the
event (for example, OnMouseDown). Next click Add Handler. Finally, ensure the
dialog box begins listening to events by adding AtlAdviseSinkMap(this,TRUE) to
OnInitDialog. To finish listening to events, add a message handler for OnDestroy and
add a call to AtlAdviseSinkMap(this, FALSE).
Creating a control at run time
The CAxWindow class provides a mechanism to create and host ActiveX controls
in a similar manner to any other window class. This may be desirable if the parent
window of the control is also created at runtime.
AtlAxWinInit();
CAxWindow wnd;
// m_hWnd is the parent window handle.
// rect is the size of ActiveX control in client coordinates.
// IDC_MYCTL is a unique ID to identify the controls window.
RECT rect = {10,10,400,300};
wnd.Create(m_hWnd, rect, _T("esriReaderControl.ReaderControl"),
WS_CHILD|WS_VISIBLE, 0, IDC_MYCTL);
Setting the buddy control property
The ToolbarControl and TOCControl need to be associated with a “buddy” control
on the dialog box. This is typically performed in the OnInitDialog windows message
handler of a dialog box.
124 • ArcGIS Engine Developer Guide