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Cómo validar y combinar PrintTickets

El esquema de impresión de Microsoft Windows incluye los elementos PrintCapabilities flexibles y PrintTicket extensibles. El primero detalla las funcionalidades de un dispositivo de impresión y este último especifica cómo el dispositivo debe usar esas funcionalidades con respecto a una secuencia determinada de documentos, documentos individuales o páginas individuales.

Una secuencia típica de tareas para una aplicación que admita la impresión sería la siguiente.

  1. Determine las funcionalidades de una impresora.

  2. Configura un PrintTicket para usar las funcionalidades.

  3. Valide el PrintTicket.

En este artículo se muestra cómo hacerlo.

Ejemplo

En el ejemplo sencillo siguiente, solo nos interesa si una impresora puede admitir dúplex , impresión en dos lados. Los pasos principales son los siguientes.

  1. Obtenga un PrintCapabilities objeto con el GetPrintCapabilities método .

  2. Pruebe la presencia de la funcionalidad que desee. En el ejemplo siguiente, probamos la propiedad DuplexingCapability del objeto PrintCapabilities para verificar la capacidad de imprimir en ambos lados de una hoja de papel con el "volteo de página" a lo largo del lado largo de la hoja. Puesto que DuplexingCapability es una colección, usamos el Contains método de ReadOnlyCollection<T>.

    Nota:

    Este paso no es estrictamente necesario. El MergeAndValidatePrintTicket método que se usa a continuación comprobará cada solicitud en comparación con las capacidades de la impresora. Si la impresora no admite la funcionalidad solicitada, el controlador de impresora sustituirá una solicitud alternativa en el PrintTicket devuelto por el método .

  3. Si la impresora admite impresión a doble cara, el código de ejemplo crea un PrintTicket que solicita esta función. Pero la aplicación no especifica todas las opciones de impresora posibles disponibles en el PrintTicket elemento . Eso sería un desperdicio tanto del programador como del tiempo del programa. En su lugar, el código establece solo la solicitud dúplex y, a continuación, combina esto PrintTicket con uno existente, totalmente configurado y validado PrintTicket, en este caso, la configuración predeterminada PrintTicket del usuario.

  4. En consecuencia, el ejemplo llama al método MergeAndValidatePrintTicket para combinar el nuevo y mínimo PrintTicket con el valor predeterminado PrintTicket del usuario. Esto devuelve un ValidationResult que incluye el nuevo PrintTicket como una de sus propiedades.

  5. A continuación, el ejemplo prueba que las nuevas PrintTicket solicitudes admiten dúplex. Si es así, el ejemplo lo convierte en el nuevo vale de impresión predeterminado para el usuario. Si se hubiera omitido el paso 2 anterior y la impresora no hubiera admitido la impresión dúplex a lo largo del lado largo, la prueba habría resultado en false. (Vea la nota anterior).

  6. El último paso significativo es confirmar el cambio de la propiedad UserPrintTicket de PrintQueue usando el método Commit.

/// <summary>
/// Changes the user-default PrintTicket setting of the specified print queue.
/// </summary>
/// <param name="queue">the printer whose user-default PrintTicket setting needs to be changed</param>
static private void ChangePrintTicketSetting(PrintQueue queue)
{
    //
    // Obtain the printer's PrintCapabilities so we can determine whether or not
    // duplexing printing is supported by the printer.
    //
    PrintCapabilities printcap = queue.GetPrintCapabilities();

    //
    // The printer's duplexing capability is returned as a read-only collection of duplexing options
    // that can be supported by the printer. If the collection returned contains the duplexing
    // option we want to set, it means the duplexing option we want to set is supported by the printer,
    // so we can make the user-default PrintTicket setting change.
    //
    if (printcap.DuplexingCapability.Contains(Duplexing.TwoSidedLongEdge))
    {
        //
        // To change the user-default PrintTicket, we can first create a delta PrintTicket with
        // the new duplexing setting.
        //
        PrintTicket deltaTicket = new PrintTicket();
        deltaTicket.Duplexing = Duplexing.TwoSidedLongEdge;

        //
        // Then merge the delta PrintTicket onto the printer's current user-default PrintTicket,
        // and validate the merged PrintTicket to get the new PrintTicket we want to set as the
        // printer's new user-default PrintTicket.
        //
        ValidationResult result = queue.MergeAndValidatePrintTicket(queue.UserPrintTicket, deltaTicket);

        //
        // The duplexing option we want to set could be constrained by other PrintTicket settings
        // or device settings. We can check the validated merged PrintTicket to see whether the
        // the validation process has kept the duplexing option we want to set unchanged.
        //
        if (result.ValidatedPrintTicket.Duplexing == Duplexing.TwoSidedLongEdge)
        {
            //
            // Set the printer's user-default PrintTicket and commit the set operation.
            //
            queue.UserPrintTicket = result.ValidatedPrintTicket;
            queue.Commit();
            Console.WriteLine("PrintTicket new duplexing setting is set on '{0}'.", queue.FullName);
        }
        else
        {
            //
            // The duplexing option we want to set has been changed by the validation process
            // when it was resolving setting constraints.
            //
            Console.WriteLine("PrintTicket new duplexing setting is constrained on '{0}'.", queue.FullName);
        }
    }
    else
    {
        //
        // If the printer doesn't support the duplexing option we want to set, skip it.
        //
        Console.WriteLine("PrintTicket new duplexing setting is not supported on '{0}'.", queue.FullName);
    }
}

''' <summary>
''' Changes the user-default PrintTicket setting of the specified print queue.
''' </summary>
''' <param name="queue">the printer whose user-default PrintTicket setting needs to be changed</param>
Private Shared Sub ChangePrintTicketSetting(ByVal queue As PrintQueue)
    '
    ' Obtain the printer's PrintCapabilities so we can determine whether or not
    ' duplexing printing is supported by the printer.
    '
    Dim printcap As PrintCapabilities = queue.GetPrintCapabilities()

    '
    ' The printer's duplexing capability is returned as a read-only collection of duplexing options
    ' that can be supported by the printer. If the collection returned contains the duplexing
    ' option we want to set, it means the duplexing option we want to set is supported by the printer,
    ' so we can make the user-default PrintTicket setting change.
    '
    If printcap.DuplexingCapability.Contains(Duplexing.TwoSidedLongEdge) Then
        '
        ' To change the user-default PrintTicket, we can first create a delta PrintTicket with
        ' the new duplexing setting.
        '
        Dim deltaTicket As New PrintTicket()
        deltaTicket.Duplexing = Duplexing.TwoSidedLongEdge

        '
        ' Then merge the delta PrintTicket onto the printer's current user-default PrintTicket,
        ' and validate the merged PrintTicket to get the new PrintTicket we want to set as the
        ' printer's new user-default PrintTicket.
        '
        Dim result As ValidationResult = queue.MergeAndValidatePrintTicket(queue.UserPrintTicket, deltaTicket)

        '
        ' The duplexing option we want to set could be constrained by other PrintTicket settings
        ' or device settings. We can check the validated merged PrintTicket to see whether the
        ' the validation process has kept the duplexing option we want to set unchanged.
        '
        If result.ValidatedPrintTicket.Duplexing = Duplexing.TwoSidedLongEdge Then
            '
            ' Set the printer's user-default PrintTicket and commit the set operation.
            '
            queue.UserPrintTicket = result.ValidatedPrintTicket
            queue.Commit()
            Console.WriteLine("PrintTicket new duplexing setting is set on '{0}'.", queue.FullName)
        Else
            '
            ' The duplexing option we want to set has been changed by the validation process
            ' when it was resolving setting constraints.
            '
            Console.WriteLine("PrintTicket new duplexing setting is constrained on '{0}'.", queue.FullName)
        End If
    Else
        '
        ' If the printer doesn't support the duplexing option we want to set, skip it.
        '
        Console.WriteLine("PrintTicket new duplexing setting is not supported on '{0}'.", queue.FullName)
    End If
End Sub

Para que pueda probar rápidamente este ejemplo, el resto de este se presenta a continuación. Cree un proyecto y un espacio de nombres y luego pegue ambos fragmentos de código de este artículo en el bloque del espacio de nombres.

/// <summary>
/// Displays the correct command line syntax to run this sample program.
/// </summary>
static private void DisplayUsage()
{
    Console.WriteLine();
    Console.WriteLine("Usage #1: printticket.exe -l \"<printer_name>\"");
    Console.WriteLine("      Run program on the specified local printer");
    Console.WriteLine();
    Console.WriteLine("      Quotation marks may be omitted if there are no spaces in printer_name.");
    Console.WriteLine();
    Console.WriteLine("Usage #2: printticket.exe -r \"\\\\<server_name>\\<printer_name>\"");
    Console.WriteLine("      Run program on the specified network printer");
    Console.WriteLine();
    Console.WriteLine("      Quotation marks may be omitted if there are no spaces in server_name or printer_name.");
    Console.WriteLine();
    Console.WriteLine("Usage #3: printticket.exe -a");
    Console.WriteLine("      Run program on all installed printers");
    Console.WriteLine();
}

[STAThread]
static public void Main(string[] args)
{
    try
    {
        if ((args.Length == 1) && (args[0] == "-a"))
        {
            //
            // Change PrintTicket setting for all local and network printer connections.
            //
            LocalPrintServer server = new LocalPrintServer();

            EnumeratedPrintQueueTypes[] queue_types = {EnumeratedPrintQueueTypes.Local,
                                                       EnumeratedPrintQueueTypes.Connections};

            //
            // Enumerate through all the printers.
            //
            foreach (PrintQueue queue in server.GetPrintQueues(queue_types))
            {
                //
                // Change the PrintTicket setting queue by queue.
                //
                ChangePrintTicketSetting(queue);
            }
        }//end if -a

        else if ((args.Length == 2) && (args[0] == "-l"))
        {
            //
            // Change PrintTicket setting only for the specified local printer.
            //
            LocalPrintServer server = new LocalPrintServer();
            PrintQueue queue = new PrintQueue(server, args[1]);
            ChangePrintTicketSetting(queue);
        }//end if -l

        else if ((args.Length == 2) && (args[0] == "-r"))
        {
            //
            // Change PrintTicket setting only for the specified remote printer.
            //
            String serverName = args[1].Remove(args[1].LastIndexOf(@"\"));
            String printerName = args[1].Remove(0, args[1].LastIndexOf(@"\")+1);
            PrintServer ps = new PrintServer(serverName);
            PrintQueue queue = new PrintQueue(ps, printerName);
            ChangePrintTicketSetting(queue);
         }//end if -r

        else
        {
            //
            // Unrecognized command line.
            // Show user the correct command line syntax to run this sample program.
            //
            DisplayUsage();
        }
    }
    catch (Exception e)
    {
        Console.WriteLine(e.Message);
        Console.WriteLine(e.StackTrace);

        //
        // Show inner exception information if it's provided.
        //
        if (e.InnerException != null)
        {
            Console.WriteLine("--- Inner Exception ---");
            Console.WriteLine(e.InnerException.Message);
            Console.WriteLine(e.InnerException.StackTrace);
        }
    }
    finally
    {
        Console.WriteLine("Press Return to continue...");
        Console.ReadLine();
    }
}//end Main

''' <summary>
''' Displays the correct command line syntax to run this sample program.
''' </summary>
Private Shared Sub DisplayUsage()
    Console.WriteLine()
    Console.WriteLine("Usage #1: printticket.exe -l ""<printer_name>""")
    Console.WriteLine("      Run program on the specified local printer")
    Console.WriteLine()
    Console.WriteLine("      Quotation marks may be omitted if there are no spaces in printer_name.")
    Console.WriteLine()
    Console.WriteLine("Usage #2: printticket.exe -r ""\\<server_name>\<printer_name>""")
    Console.WriteLine("      Run program on the specified network printer")
    Console.WriteLine()
    Console.WriteLine("      Quotation marks may be omitted if there are no spaces in server_name or printer_name.")
    Console.WriteLine()
    Console.WriteLine("Usage #3: printticket.exe -a")
    Console.WriteLine("      Run program on all installed printers")
    Console.WriteLine()
End Sub


<STAThread>
Public Shared Sub Main(ByVal args() As String)
    Try
        If (args.Length = 1) AndAlso (args(0) = "-a") Then
            '
            ' Change PrintTicket setting for all local and network printer connections.
            '
            Dim server As New LocalPrintServer()

            Dim queue_types() As EnumeratedPrintQueueTypes = {EnumeratedPrintQueueTypes.Local, EnumeratedPrintQueueTypes.Connections}

            '
            ' Enumerate through all the printers.
            '
            For Each queue As PrintQueue In server.GetPrintQueues(queue_types)
                '
                ' Change the PrintTicket setting queue by queue.
                '
                ChangePrintTicketSetting(queue)
            Next queue 'end if -a

        ElseIf (args.Length = 2) AndAlso (args(0) = "-l") Then
            '
            ' Change PrintTicket setting only for the specified local printer.
            '
            Dim server As New LocalPrintServer()
            Dim queue As New PrintQueue(server, args(1))
            ChangePrintTicketSetting(queue) 'end if -l

        ElseIf (args.Length = 2) AndAlso (args(0) = "-r") Then
            '
            ' Change PrintTicket setting only for the specified remote printer.
            '
            Dim serverName As String = args(1).Remove(args(1).LastIndexOf("\"))
            Dim printerName As String = args(1).Remove(0, args(1).LastIndexOf("\")+1)
            Dim ps As New PrintServer(serverName)
            Dim queue As New PrintQueue(ps, printerName)
            ChangePrintTicketSetting(queue) 'end if -r

        Else
            '
            ' Unrecognized command line.
            ' Show user the correct command line syntax to run this sample program.
            '
            DisplayUsage()
        End If
    Catch e As Exception
        Console.WriteLine(e.Message)
        Console.WriteLine(e.StackTrace)

        '
        ' Show inner exception information if it's provided.
        '
        If e.InnerException IsNot Nothing Then
            Console.WriteLine("--- Inner Exception ---")
            Console.WriteLine(e.InnerException.Message)
            Console.WriteLine(e.InnerException.StackTrace)
        End If
    Finally
        Console.WriteLine("Press Return to continue...")
        Console.ReadLine()
    End Try
End Sub

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