Sub PreviewWindowSet( _
   ByVal _bsChannelID As String, _
   ByVal _hWndParent As Long _
) 

void PreviewWindowSet( 
   string _bsChannelID,
   long _hWndParent
)

procedure PreviewWindowSet( 
    _bsChannelID: String;
    _hWndParent: Int64
); 

void PreviewWindowSet( 
   BSTR* _bsChannelID,
   long _hWndParent
) 

Parameters

_bsChannelID

channel ID. By default use empty string

_hWndParent

handle of a control where preview will be displayed

Here is example of how to initialize a preview:

m_objPreview = new MFPreviewClass();
//Configure preview
m_objPreview.PreviewWindowSet("", panelPreview.Handle.ToInt32());
m_objPreview.PreviewEnable("", 1, 1);

Reference

IMPreview Interface
IMPreview Members