public static IChangeNotification Create(PRINTER_CHANGE changes,
string printerName = null,
PRINTER_NOTIFY_CATEGORY category = PRINTER_NOTIFY_CATEGORY.PRINTER_NOTIFY_CATEGORY_ALL,
NotifyOptions options = null)
{
var notification = new ChangeNotification
{
_printerHandle = OpenPrinter(printerName)
};
var ptrNotifyOptions = IntPtr.Zero;
try
{
if (options != null)
{
var size = SizeOfNotifyOptions(options);
ptrNotifyOptions = Marshal.AllocHGlobal(size);
ToPtr(ptrNotifyOptions, options);
}
notification._changeHandle = NativeMethods.FindFirstPrinterChangeNotification(
notification._printerHandle,
(UInt32)changes,
(UInt32)category,
ptrNotifyOptions);
if (notification._changeHandle == INVALID_HANDLE_VALUE)
{
throw new Win32Exception();
}
// Don't let SafeWaitHandle own the handle as it can't close it
notification.SafeWaitHandle = new SafeWaitHandle(notification._changeHandle, false);
}
catch
{
NativeMethods.ClosePrinter(notification._printerHandle);
throw;
}
finally
{
Marshal.FreeHGlobal(ptrNotifyOptions);
}
return(notification);
}
private static void MonitorPrinter(string printerName, NotifyOptions printerNotifyOptions, PRINTER_CHANGE change)
{
if (printerNotifyOptions == null && change == 0)
{
throw new Exception("Either or both of printer changes or fields to monitor must be set.");
}
using var printerChangeNotification = ChangeNotification.Create(change,
printerName,
PRINTER_NOTIFY_CATEGORY.PRINTER_NOTIFY_CATEGORY_ALL, printerNotifyOptions);
while (true)
{
printerChangeNotification.WaitHandle.WaitOne();
NotifyInfo printerNotifyInfo;
bool refresh = false;
do
{
printerNotifyInfo = printerChangeNotification.FindNextPrinterChangeNotification(refresh);
WriteToConsole(printerNotifyInfo);
refresh = true; // For next iteration if data overflowed
} while ((printerNotifyInfo.Flags & NotifyInfo.PRINTER_NOTIFY_INFO_DISCARDED) != 0);
}
}
