FindFirstPrinterChangeNotification

FindFirstPrinterChangeNotification

The FindFirstPrinterChangeNotification function creates a change notification object and returns a handle to the object. You can then use this handle in a call to one of the wait functions to monitor changes to the printer or print server.

The FindFirstPrinterChangeNotification call specifies the type of changes to be monitored. You can specify a set of conditions to monitor for changes, a set of printer information fields to monitor, or both.

A wait operation on the change notification handle succeeds when one of the specified changes occurs in the specified printer or print server. You then call the FindNextPrinterChangeNotification function to retrieve information about the change, and to reset the change notification object for use in the next wait operation.

HANDLE FindFirstPrinterChangeNotification(

HANDLE hPrinter,	// handle to printer or print server to monitor for changes
DWORD fdwFlags,	// flags that specify the conditions to monitor
DWORD fdwOptions,	// reserved, must be zero
LPVOID pPrinterNotifyOptions	// pointer to structure specifying printer information to monitor
);

Parameters

hPrinter

Handle to the printer or print server that you want to monitor. This handle is obtained by calling the OpenPrinter function.

fdwFlags

A set of bit flags that specify the conditions that will cause the change notification object to enter a signaled state. A change notification occurs when one or more of the specified conditions are met. The fdwFlags parameter can be zero if pPrinterNotifyOptions is non-NULL.

You can set one or more of the following change notification constants:

Value

Meaning

PRINTER_CHANGE_FORM

Notify of any changes to a form. You can set this general flag or one or more of the following specific flags:
PRINTER_CHANGE_ADD_FORM PRINTER_CHANGE_SET_FORM PRINTER_CHANGE_DELETE_FORM

PRINTER_CHANGE_JOB

Notify of any changes to a job. You can set this general flag or one or more of the following specific flags:
PRINTER_CHANGE_ADD_JOB PRINTER_CHANGE_SET_JOB PRINTER_CHANGE_DELETE_JOB PRINTER_CHANGE_WRITE_JOB

PRINTER_CHANGE_PORT

Notify of any changes to a port. You can set this general flag or one or more of the following specific flags:
PRINTER_CHANGE_ADD_PORT PRINTER_CHANGE_CONFIGURE_PORT PRINTER_CHANGE_DELETE_PORT

PRINTER_CHANGE_PRINT_PROCESSOR

Notify of any changes to a print processor. You can set this general flag or one or more of the following specific flags: PRINTER_CHANGE_ADD_PRINT_PROCESSOR PRINTER_CHANGE_DELETE_PRINT_PROCESSOR

PRINTER_CHANGE_PRINTER

Notify of any changes to a printer. You can set this general flag or one or more of the following specific flags:
PRINTER_CHANGE_ADD_PRINTER PRINTER_CHANGE_SET_PRINTER PRINTER_CHANGE_DELETE_PRINTER PRINTER_CHANGE_FAILED_CONNECTION_PRINTER

PRINTER_CHANGE_PRINTER_DRIVER

Notify of any changes to a printer driver. You can set this general flag or one or more of the following specific flags:
PRINTER_CHANGE_ADD_PRINTER_DRIVER PRINTER_CHANGE_SET_PRINTER_DRIVER PRINTER_CHANGE_DELETE_PRINTER_DRIVER

PRINTER_CHANGE_ALL

Notify if any of the preceding changes occur.

For descriptions of the more specific flags in the preceding table, see the FindNextPrinterChangeNotification function.

fdwOptions

Reserved; must be zero.

pPrinterNotifyOptions

Pointer to a PRINTER_NOTIFY_OPTIONS structure. The pTypes member of this structure points to an array of one or more PRINTER_NOTIFY_OPTIONS_TYPE structures, each of which specifies a printer information field to monitor. A change notification occurs when one or more of the specified fields changes. When a change occurs, the FindNextPrinterChangeNotification function can retrieve the new printer information. This parameter can be NULL if fdwFlags is nonzero.

For a list of fields that can be monitored, see PRINTER_NOTIFY_OPTIONS_TYPE.

Return Values

If the function succeeds, the return value is a handle to a change notification object associated with the specified printer or print server.

If the function fails, the return value is INVALID_HANDLE_VALUE. To get extended error information, call GetLastError.

Remarks

To monitor a printer or print server, call the FindFirstPrinterChangeNotification function, then use the returned change notification object handle in a call to one of the wait functions. A wait operation on a change notification object is satisfied when the change notification object enters the signaled state. The system signals the object when one or more of the changes specified by fdwFlags or pPrinterNotifyOptions occurs in the monitored printer or print server.

When you call FindFirstPrinterChangeNotification, either fdwFlags must be nonzero or pPrinterNotifyOptions must be non-NULL. If both are specified, notifications will occur for both.

When a wait operation on a printer change notification object is satisfied, call the FindNextPrinterChangeNotification function to determine the cause of the notification. For a condition specified by fdwFlags, FindNextPrinterChangeNotification reports the condition or conditions that changed. For a printer information field specified by pPrinterNotifyOptions , FindNextPrinterChangeNotification reports the field or fields that changed as well as the new information for these fields. FindNextPrinterChangeNotification also resets the change notification object to the nonsignaled state so you can use it in another wait operation to continue monitoring the printer or print server.

Do not call the FindNextPrinterChangeNotification function if the change notification object is not in the signaled state. If the wait function returns the value WAIT_TIMEOUT, the change object is not in the signaled state. Call the FindNextPrinterChangeNotification function only if the wait function succeeds without timing out.

When you no longer need the change notification object, close it by calling the FindClosePrinterChangeNotification function.

The three Find*PrinterChangeNotification functions, in combination with the wait functions, provide an asynchronous and resource-efficient alternative to the WaitForPrinterChange function.