The IPrint interface enables OLE objects in general and document objects in particular to support programmatic printing. Once a document is loaded, containers and other clients can call IPrint::Print to instruct a document to print itself specifying printing control flags, the target device, the particular pages to print, and other options. The client can also control the continuation of printing by calling the IContinueCallback interface. In the future, additional print-related interfaces may be defined that will be available through QueryInterface where IPrint represents merely a base level of support.
An object that implements IPrint registers itself with the ôPrintableö key stored under its CLSID as follows:
HKEY_CLASSES_ROOT\CLSID\{...}\Printable
Callers determine whether a particular object class supports programmatic printing of its persistent state by looking in the registry for the ôPrintableö key.
When to Implement
Implementing IPrint is optional. You will usually implement IPrint on whatever object is able to load the persistent state of a given document type; that is, on the same object that also implements either IPersistFile or IPersistStorage for that type.
When to Use
Call IPrint when you want an object to print its current state. Using this interface, a caller can tell the object to print itself, set the initial page number of the printed document, and return both the number of pages and the number of the first page to be printed.
Methods in VTable Order
IUnknown Methods Description
QueryInterface
Returns pointers to supported interfaces
AddRef Increments reference count
Release Decrements reference count
IPrint Methods Description
SetInitialPageNum
Sets number of first page
GetPageInfo Returns number of pages and number of first
page
Print Prints objectÆs persistent state