Creating the WIA Driver Item Tree
After the minidriver is initialized, it must create the driver item tree in the IWiaMiniDrv::drvInitializeWia method by:
Creating the driver item tree if it does not already exist. The minidriver sets the root item flags and creates the root item by calling the driver services library function wiasCreateDrvItem. The minidriver stores the returned pointer to the root item in a private member variable.
Creating child items for each item on the device using the wiasCreateDrvItem function. This function creates a device-specific context where the minidriver can store information about the item.
Calling the IWiaDrvItem::AddItemToFolder method on each child item to add the item to the driver item tree.