by Conrad Herrmann
25 May 97
Updated 12 Feb 1998

function ClientSite( obj: IUnknown ): IOleClientSite;
var
  Site: IOleClientSite;
  OleObj: IOleObject;
begin
if (obj.QueryInterface( IOleObject, OleObj ) = S_OK) and
(OleObj.GetClientSite( Site ) = S_OK) then
  Result := Site
else
  Result := nil;
end; 

The obj parameter is your ActiveX Control. For example, you can call from

within a method of your control using the following code:

type TButtonX = class(TActiveXControl)
  ...
end;
...
procedure TButtonX.Click;
var 
  Site: IOleClientSite;
begin
  Site := ClientSite(Self);
end;

The site reference is the only means your control has for communicating with its container. By query-casting the site reference to other interfaces, your can gain access to extended container information. Some of the more interesting site interfaces:

• IDispatch: the ambient properties of your control.
• IServiceProvider: how you get to control an IDE, among other things.
• IOleInPlaceSite: how you can query info about the windows you're embedded in, including the interfaces that will be able to return the handle of the frame window or the document window containing you.