DrvPrinterEvent function

A printer interface DLL's DrvPrinterEvent function is called by the print spooler when processing printer-specific events that might require action by the printer driver.


BOOL DrvPrinterEvent(
  LPWSTR pPrinterName,
  int    DriverEvent,
  DWORD  Flags,
  LPARAM lParam



Caller-supplied pointer to a NULL-terminated printer name string. The string format can be \Machine<i>PrinterName to specify a remote printer, or PrinterName to specify a local printer.


Caller-supplied event code identifying the event. The following event codes are defined:

Event Code Definition
PRINTER_EVENT_ADD_CONNECTION The spooler has just finished processing a call to its AddPrinterConnection function (described in the Microsoft Windows SDK documentation), which allows a client user to connect to a previously created remote printer.
PRINTER_EVENT_ATTRIBUTES_CHANGED The attribute bits for a printer have changed. In response to an application's call to the SetPrinter function (described in the Windows SDK documentation), the spooler calls the printer driver's DrvPrinterEvent function, passing the event code in the call. When this event code is used, the lParam parameter points to a PRINTER_EVENT_ATTRIBUTES_INFO structure that describes the old and the new attributes.
PRINTER_EVENT_CACHE_DELETE The spooler is deleting the client's file cache.
PRINTER_EVENT_CACHE_REFRESH The spooler is updating the client's cached files.
PRINTER_EVENT_CONFIGURATION_UPDATE The printer configuration has changed. When this event code is used, the lParam parameter points to a Unicode string that contains a notification formatted according the Bidi Notification Schema.
PRINTER_EVENT_DELETE_CONNECTION The spooler has just finished processing a call to its DeletePrinterConnection function (described in the Windows SDK documentation), which allows a client user to remove a printer connection.
PRINTER_EVENT_DELETE The spooler has just finished processing a call to its DeletePrinter function (described in the Windows SDK documentation), which allows an administrator to delete a printer instance.
PRINTER_EVENT_INITIALIZE The spooler has just finished processing a call to its AddPrinter function, which allows an administrator to make a printer available on a server, or its SetPrinter function, which allows an administrator to modify a printer's state. AddPrinter and SetPrinter are described in the Windows SDK documentation.

In a client-side rendering connection, the client computer has just added the GUID printer.

The PRINTER_EVENT_INITIALIZE event specifies a NULL lParam parameter value for DrvPrinterEvent calls on Windows Vista and earlier releases. For Windows 7 and later releases, the lParam parameter is a user token handle. The print drivers may use the returned token handle to query user data or impersonate the user.


Caller-supplied bit flag, defined as follows:

Value Definition
PRINTER_EVENT_FLAG_NO_UI If set, the function mustnot display a user interface. During the installation of a print processor, print monitor, or printer driver, the only way in which a user interface is permitted is through the use of the VendorSetup directive. See Printer INF File Entries and Customized Printer Setup Operations for more information.
Important  : Be aware that VendorSetup is now deprecated and should not be used by any new v3 or v4 drivers that you develop. This information about VendorSetup is provided for reference only, or for the maintenance of existing v3 drivers that already use this INF directive.


Not used unless the DriverEvent parameter is set to PRINTER_EVENT_ATTRIBUTES_CHANGED. In this case, lParam contains the address of a PRINTER_EVENT_ATTRIBUTES_INFO structure. (See the preceding description of the DriverEvent parameter.) For all other values of the DriverEvent parameter, the lParam parameter is NULL.

Return Value

If the operation succeeds, the function should return TRUE; otherwise, it should return FALSE. Currently, however, the only time the function's return value is checked is when the spooler has called DrvPrinterEvent during processing of the AddPrinter function, with DriverEvent set to PRINTER_EVENT_INITIALIZE. If DrvPrinterEvent returns FALSE in this case, the spooler does not create the printer and instead causes AddPrinter to fail.


All printer interface DLLs must provide a DrvPrinterEvent function, and the function must support the PRINTER_EVENT_INITIALIZE event code. Support for all other event codes is optional.

Registry settings stored when handling a PRINTER_EVENT_INITIALIZE event should be stored under the HKEY_LOCAL_MACHINE key by calling SetPrinterData. For the PRINTER_EVENT_INITIALIZE and PRINTER_EVENT_DELETE event codes, the spooler verifies that the caller has administrative privilege and calls DrvPrinterEvent while impersonating the caller.

In contrast, if you need to store settings in the registry when handling a PRINTER_EVENT_ADD_CONNECTION event, the printer interface DLL should write them under the HKEY_CURRENT_USER key so that they are stored on a per-user basis. Then if a user with a roaming profile logs onto another system, the connection follows the user. The DrvPrinterEvent function is called only when the user first makes the connection, and not when the user subsequently logs onto other systems using the roaming profile.

For the PRINTER_EVENT_ADD_CONNECTION and PRINTER_EVENT_DELETE_CONNECTION event codes, the DrvPrinterEvent function's execution context is the calling application (usually the Print Folder), and the function can display a user interface. For all other event codes, the execution context is the print spooler and a user interface cannot be displayed.

An example of a driver that might display a user interface when a connection is made is a FAX driver, which could prompt the user for the name and telephone number of the user (FAX sender), and save the information until the connection is deleted.

An example of the type of file that might be stored in a client cache is a large font-metrics file that contains too much information to be written to the registry. When the DrvPrinterEvent function's event code is PRINTER_EVENT_CACHE_REFRESH, the printer interface DLL can reload the file from the server to ensure the cache is up to date.


Target Platform Desktop
Header winddiui.h (include Winddiui.h)