【WPF.NET开发】验证和合并 PrintTicket

本文内容

Microsoft Windows 打印架构
包括灵活且可扩展的 PrintCapabilities 和 PrintTicket 元素。 前一个元素逐条列出打印设备的功能，后一个指定设备应如何使用这些功能来处理特定文档序列、单个文档或单个页面。

支持打印的应用程序的典型任务序列应如下。

1. 确定打印机的功能。

2. 配置一个 PrintTicket，用来使用这些功能。

3. 验证 PrintTicket。

本文介绍如何执行此操作。

示例

在下面的简单示例中，我们仅对打印机是否支持双工（即双面打印）感兴趣。 主要步骤如下。

1. 使用 GetPrintCapabilities 方法获取 PrintCapabilities 对象。

2. 测试是否有你需要的功能。 在下面的示例中，我们测试 PrintCapabilities 对象的 DuplexingCapability 属性是否有以下功能：在一张纸的两面进行打印，并沿纸张的长边“翻页”。 DuplexingCapability 是集合，因此我们使用 Contains 的 ReadOnlyCollection 方法。

    备注

   此步骤不是绝对必需的。 下面使用的 MergeAndValidatePrintTicket 方法将根据打印机的功能检查 PrintTicket 中的每个请求。 如果打印机不支持请求的功能，打印机驱动程序将在方法返回的 PrintTicket 中用备用请求作为替代。

3. 如果打印机支持双工，示例代码创建要求双工的 PrintTicket。 但应用程序不指定 PrintTicket 元素中可用的每个可能的打印机设置。 那样做会在程序员和程序时间两个方面产生浪费。 相反，代码只设置双工请求，然后将此 PrintTicket 与已完全配置且验证的现有 PrintTicket 合并，在本例中为用户的默认 PrintTicket。

4. 相应的，该示例调用 MergeAndValidatePrintTicket 方法将新的最小 PrintTicket 与用户的默认 PrintTicket 合并。 这会返回一个 ValidationResult 属性，它包含 PrintTicket 作为其属性之一。

5. 然后，该示例测试新的 PrintTicket 请求双工。 如果是这样，该示例接下来将它设为用户的新的默认打印工单。 如果漏掉了上面的步骤 2，并且打印机不支持沿长边双工，测试会得出 false。 （请参阅上面的说明。）

6. 最后一个重要步骤是使用 Commit 方法将更改提交到 PrintQueue 的 UserPrintTicket 属性。

/// 

/// Changes the user-default PrintTicket setting of the specified print queue.
/// 
/// the printer whose user-default PrintTicket setting needs to be changed
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);
    }
}

这样，你就能快速地测试此示例，下面显示了该示例的其余部分。 创建项目和命名空间，然后将本文中的两个代码片段粘贴到命名空间块中。

/// 

/// Displays the correct command line syntax to run this sample program.
/// 
static private void DisplayUsage()
{
    Console.WriteLine();
    Console.WriteLine("Usage #1: printticket.exe -l \"\"");
    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 \"\\\\\\\"");
    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