private static void ToPtr(IntPtr pos, NotifyOptions options)
{
PRINTER_NOTIFY_OPTIONS st;
st.Flags = options.Flags;
st.Count = (uint)options.Types.Count;
st.Version = 2;
st.pTypes = pos + Marshal.SizeOf <PRINTER_NOTIFY_OPTIONS>();
Marshal.StructureToPtr(st, pos, false);
pos += Marshal.SizeOf <PRINTER_NOTIFY_OPTIONS>();
var fieldsPos = pos + (options.Types.Count * Marshal.SizeOf <PRINTER_NOTIFY_OPTIONS_TYPE>());
foreach (var optionsType in options.Types)
{
PRINTER_NOTIFY_OPTIONS_TYPE str = default;
str.Type = (UInt16)optionsType.Type;
str.Count = (UInt32)optionsType.Fields.Count;
str.pFields = fieldsPos;
Marshal.StructureToPtr(str, pos, false);
pos += Marshal.SizeOf <PRINTER_NOTIFY_OPTIONS_TYPE>();
foreach (var field in optionsType.Fields)
{
Marshal.WriteInt32(fieldsPos, field);
fieldsPos += Marshal.SizeOf(field.GetType());
}
}
}
private static int SizeOfNotifyOptions(NotifyOptions options)
{
var size = Marshal.SizeOf <PRINTER_NOTIFY_OPTIONS>();
foreach (var printerNotifyOptionsType in options.Types)
{
size += Marshal.SizeOf <PRINTER_NOTIFY_OPTIONS_TYPE>();
size += printerNotifyOptionsType.Fields.Count * Marshal.SizeOf <UInt32>();
}
return(size);
}
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);
}
