FindNextPrinterChangeNotification info  Overview  Group

The FindNextPrinterChangeNotification function retrieves information about the most recent change notification for a change notification object associated with a printer or print server. Call this function when a wait operation on the change notification object is satisfied.

The function also resets the change notification object to the not-signaled state. You can then use the object in another wait operation to continue monitoring the printer or print server. The operating system will set the object to the signaled state the next time one of a specified set of changes occurs to the printer or print server. The FindFirstPrinterChangeNotification function creates the change notification object and specifies the set of changes to be monitored.

BOOL FindNextPrinterChangeNotification(

HANDLE hChange,	// handle to change notification object of interest
PDWORD pdwChange,	// pointer to a value that indicates the condition that changed
LPVOID pPrinterNotifyOptions,	// pointer to a structure that specifies a refresh flag
LPVOID *ppPrinterNotifyInfo	// pointer to a pointer that receives printer information buffer
);

Parameters

hChange

Handle to a change notification object associated with a printer or print server. You obtain such a handle by calling the FindFirstPrinterChangeNotification function. The operating system sets this change notification object to the signaled state when it detects one of the changes specified in the object’s change notification filter.

pdwChange

Pointer to a doubleword variable whose bits are set to indicate the changes that occurred to cause the most recent notification. The bit flags that might be set correspond to those specified in the fdwFlags parameter of the FindFirstPrinterChangeNotification call. The system sets one or more of the following bit flags:

Value	Meaning
PRINTER_CHANGE_ADD_FORM
	A form was added to the server.
PRINTER_CHANGE_ADD_JOB
	A print job was sent to the printer.
PRINTER_CHANGE_ADD_PORT
	A port or monitor was added to the server.
PRINTER_CHANGE_ADD_PRINT_PROCESSOR
	A print processor was added to the server.
PRINTER_CHANGE_ADD_PRINTER
	A printer was added to the server.
PRINTER_CHANGE_ADD_PRINTER_DRIVER
	A printer driver was added to the server.
PRINTER_CHANGE_CONFIGURE_PORT
	A port was configured on the server.
PRINTER_CHANGE_DELETE_FORM
	A form was deleted from the server.
PRINTER_CHANGE_DELETE_JOB
	A job was deleted.
PRINTER_CHANGE_DELETE_PORT
	A port or monitor was deleted from the server.
PRINTER_CHANGE_DELETE_PRINT_PROCESSOR
	A print processor was deleted from the server.
PRINTER_CHANGE_DELETE_PRINTER
	A printer was deleted.
PRINTER_CHANGE_DELETE_PRINTER_DRIVER
	A printer driver was deleted from the server.
PRINTER_CHANGE_FAILED_CONNECTION_PRINTER
	A printer connection has failed.
PRINTER_CHANGE_SET_FORM
	A form was set on the server.
PRINTER_CHANGE_SET_JOB
	A job was set.
PRINTER_CHANGE_SET_PRINTER
	A printer was set.
PRINTER_CHANGE_SET_PRINTER_DRIVER
	A printer driver was set.
PRINTER_CHANGE_WRITE_JOB
	Job data was written.

pPrinterNotifyOptions

Pointer to a PRINTER_NOTIFY_OPTIONS structure. Set the Flags member of this structure to PRINTER_NOTIFY_OPTIONS_REFRESH, to cause the function to return the current data for all monitored printer information fields. The function ignores all other members of the structure. This parameter can be NULL.

ppPrinterNotifyInfo

Pointer to a pointer variable that receives the address of a system-allocated, read-only buffer. Call the FreePrinterNotifyInfo function to free the buffer when you are finished with it. This parameter can be NULL if no information is required.

The buffer contains a PRINTER_NOTIFY_INFO structure, which contains an array of PRINTER_NOTIFY_INFO_DATA structures. Each element of the array contains information about one of the fields specified in the pPrinterNotifyOptions parameter of the FindFirstPrinterChangeNotification call. Typically, the function provides data only for the fields that changed to cause the most recent notification. However, if the structure pointed to by the pPrinterNotifyOptions parameter specifies PRINTER_NOTIFY_OPTIONS_REFRESH, the function provides data for all monitored fields.

If the PRINTER_NOTIFY_INFO_DISCARDED bit is set in the Flags member of the PRINTER_NOTIFY_INFO structure, an overflow or error occurred, and notifications may have been lost. In this case, no additional notifications will be sent until you make a second FindNextPrinterChangeNotification call that specifies PRINTER_NOTIFY_OPTIONS_REFRESH.

Return Values

If the function succeeds, the return value is nonzero.

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

Remarks

Call the FindNextPrinterChangeNotification function after a wait operation on a notification object created by FindFirstPrinterChangeNotification has been satisfied. Calling FindNextPrinterChangeNotification lets you obtain information about the change that satisfied the wait operation, and resets the notification object so it can be signaled when the next change occurs.

Do not call the FindNextPrinterChangeNotification function if the change notification object is not in the signaled state. If a 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.

To continue monitoring the printer or print server for changes, repeat the cycle of calling one of the wait functions, and then calling the FindNextPrinterChangeNotification function to examine the change and reset the notification object.

FindNextPrinterChangeNotification may combine multiple changes to the same printer information field into a single notification. When this occurs, the function typically collapses all changes for the field into a single entry in the array of PRINTER_NOTIFY_INFO_DATA structures in ppPrinterNotifyInfo; the single entry reports only the most current information. However, for some job and printer information fields, the function can return multiple array entries for the same field. In this case, the last array entry for the field reports the current data, and the earlier entries contain the data for the intermediate stages.

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

See Also

FindClosePrinterChangeNotification, FindFirstPrinterChangeNotification, PRINTER_NOTIFY_INFO, PRINTER_NOTIFY_INFO_DATA, PRINTER_NOTIFY_OPTIONS 

Questions:

• h.shibuya@vertexsystems.co.jp asks: " pdwChange is changed. However,*ppPrinterNotifyInfo is always NULL. Why? And then pdwChange is 0x7777fff7. My OS is Xp Pro+SP2."