Callback Object for the Print Property Sheet

An application that displays a Print property sheet can implement a callback object to receive notifications and messages from the PrintDlgEx function while the property sheet is displayed. To provide a callback object, specify a pointer to the object in the lpCallback member of the PRINTDLGEX structure.

The callback object must implement the IPrintDialogCallback interface. The PrintDlgEx function calls IPrintDialogCallback methods in the following situations:

• When the dialog box has been initialized
• When the user selects a different printer from the list of installed printers displayed by the property sheet
• When it receives messages for the child dialog box in the lower portion of the property sheet's General page

The callback object should also implement the IObjectWithSite interface. The PrintDlgEx function calls the IObjectWithSite::SetSite method to pass a pointer to an IPrintDialogServices interface to an application. The IPrintDialogCallback methods can use the IPrintDialogServices interface to retrieve information about the currently selected printer. The IPrintDialogServices interface is also useful for applications that create additional pages to follow the General page of the Print property sheet. The dialog box procedures for the additional pages can call IPrintDialogServices methods.