How to manage print jobs in a Windows Store device app

In Windows 8.1, Windows Store device apps for printers can manage print jobs. This topic uses the C# version of the Print job management and printer maintenance sample to demonstrate how to create a view of print jobs, monitor those jobs, and if necessary, cancel a job. To learn more about Windows Store device apps in general, see Meet Windows Store device apps.

The C# version of the Print job management and printer maintenance sample demonstrates printer maintenance with the DeviceMaintenance.xaml.cs file in the DeviceAppForPrinters2 project. To work with Bidi, the sample uses the printer extension library in the PrinterExtensionLibrary project. The printer extension library provides a convenient way to to access the printer extension interfaces of the v4 print driver. For more info, see the Printer extension library overview.

Note  The code examples shown in this topic are based on the C# version of the Print job management and printer maintenance sample. This sample is also available in JavaScript and C++. Note that because C++ can access COM directly, the C++ version of the sample does not include code library projects. Download the samples to see the latest versions of the code.

Managing print jobs

Windows 8.1 introduces new printer extension interfaces in the v4 printer driver that you can use for managing print jobs: IPrinterQueue2, IPrinterQueueView, IPrinterQueueViewEvent, IPrintJob, and IPrintJobCollection. These interfaces make it possible to monitor and cancel print jobs. For more info, see Print job management (v4 Printer Driver).

Tip  C# and JavaScript apps can't work with COM APIs directly. If you're writing a C# or JavaScript Windows Store device app, use the printer extension library to access these interfaces (as shown in this topic).

Prerequisites

Before you get started:

  1. Make sure your printer is installed using a v4 print driver. For more info, see Developing v4 print drivers.
  2. Get your development PC set up. See Getting started for info about downloading the tools and creating a developer account.
  3. Associate your app with the store. See Create a Windows Store device app for info about that.
  4. Create device metadata for your printer that associates it with your app. See Create device metadata for more about that.
  5. Build the UI for the main page of your app. All Windows Store device apps can be launched from Start, where they'll be displayed full-screen. Use the Start experience to highlight your product or services in a way that matches the specific branding and features of your devices. There are no special restrictions on the type of UI controls it can use. To get started with the design of the full-screen experience, see the Windows Store design principles.
  6. If you're writing you're writing your app with C# or JavaScript, add the PrinterExtensionLibrary project to your Windows Store device app solution. You can find this project in the Print job management and printer maintenance sample.

    Note  Because C++ can access COM directly, C++ apps do not require a separate library to work with the COM-based printer device context.

Step 1: Find printer

Before your app can manage print jobs, it must first locate the printer having the print jobs. To do this, the Print job management and printer maintenance sample includes a handy class named PrinterEnumeration (in the PrinterEnumeration.cs file). This class finds all the printers that are associated with your app via device metadata, and returns a list of PrinterInfo objects, which contains the names and device IDs for each printer.

This example shows the EnumeratePrinters_Click method in the PrintJobManagement.xaml.cs file. It shows how the sample uses the PrinterEnumeration class to get a list of associated printers.


private async void EnumeratePrinters_Click(object sender, RoutedEventArgs e)
{
    try
    {
        rootPage.NotifyUser("Enumerating printers. Please wait", NotifyType.StatusMessage);

        // Retrieve the running app's package family name, and enumerate associated printers.
        string currentPackageFamilyName = Windows.ApplicationModel.Package.Current.Id.FamilyName;

        // Enumerate associated printers.
        PrinterEnumeration pe = new PrinterEnumeration(currentPackageFamilyName);
        List<PrinterInfo> associatedPrinters = await pe.EnumeratePrintersAsync();

        // Update the data binding source on the combo box that displays the list of printers.
        PrinterComboBox.ItemsSource = associatedPrinters;
        if (associatedPrinters.Count > 0)
        {
            PrinterComboBox.SelectedIndex = 0;
            rootPage.NotifyUser(associatedPrinters.Count + " printers enumerated", NotifyType.StatusMessage);
        }
        else
        {
            rootPage.NotifyUser(DisplayStrings.NoPrintersEnumerated, NotifyType.ErrorMessage);
        }
    }
    catch (Exception exception)
    {
        rootPage.NotifyUser("Caught an exception: " + exception.Message, NotifyType.ErrorMessage);
    }
}


Tip  For more info about the PrinterEnumeration and PrinterInfo classes, see the PrinterEnumeration.cs file.

Step 2: Get printer queue

Once you've identified the printer having the print jobs that you want to manage, create a view of the print jobs, with object based on the IPrinterQueueView interface (defined in the PrinterExtensionTypes.cs file of the PrinterExtensionLibrary project). In the Print job management and printer maintenance sample, this object is named currentPrinterQueueView and is re-created each time the printer selection changes.

In the Printer_SelectionChanged method, the sample first uses a PrinterInfo object to create a printer extension context object named context. Then it uses the GetPrinterQueueView method on the context to create the currentPrinterQueueView object. Finally, an event handler is added to handle the currentPrinterQueueView's OnChanged event.

This example shows the Printer_SelectionChanged method in the PrintJobManagement.xaml.cs file. It shows how to create a printer queue view object based on IPrinterQueueView.


private void Printer_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    try
    {
        // Remove the current printer queue view (if any) before displaying the new view.
        if (currentPrinterQueueView != null)
        {
            currentPrinterQueueView.OnChanged -= OnPrinterQueueViewChanged;
            currentPrinterQueueView = null;
        }

        // Retrieve a COM IPrinterExtensionContext object, using the static WinRT factory.
        // Then instantiate one "PrinterExtensionContext" object that allows operations on the COM object.
        PrinterInfo queue = (PrinterInfo)PrinterComboBox.SelectedItem;
        Object comComtext = Windows.Devices.Printers.Extensions.PrintExtensionContext.FromDeviceId(queue.DeviceId);
        PrinterExtensionContext context = new PrinterExtensionContext(comComtext);

        // Display the printer queue view.
        const int FirstPrintJobEnumerated = 0;
        const int LastPrintJobEnumerated = 10;

        currentPrinterQueueView = context.Queue.GetPrinterQueueView(FirstPrintJobEnumerated, LastPrintJobEnumerated);
        currentPrinterQueueView.OnChanged += OnPrinterQueueViewChanged;
    }
    catch (Exception exception)
    {
        rootPage.NotifyUser("Caught an exception: " + exception.Message, NotifyType.ErrorMessage);
    }
}


Also, whenever there is a change to the view of the print jobs, an event handler calls the OnPrinterQueueViewChanged method. This method is responsible for re-binding the PrintJobListBox with an IEnumerable collection of IPrintJob objects. The collection is passed to the method via the PrinterQueueViewEventArgs object, which is defined in the PrinterExtensionTypes.cs file.

This example shows the OnPrinterQueueViewChanged method in the PrintJobManagement.xaml.cs file.


private async void OnPrinterQueueViewChanged(object sender, PrinterQueueViewEventArgs e)
{
    await Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
    {
        // Update the data binding on the ListBox that displays print jobs.
        PrintJobListBox.ItemsSource = e.Collection;
        if (PrintJobListBox.Items.Count > 0)
        {
            // If there are print jobs in the current view, mark the first job as selected.
            PrintJobListBox.SelectedIndex = 0;
        }
    });
}


Step 3: Display print job status

Because the PrintJobListBox is bound to a collection of IPrintJob objects, displaying the status of a job is fairly straightforward. The selected print job is cast as an IPrintJob object, and then the properties of that object are used to fill the PrintJobDetails TextBox.

In the Print job management and printer maintenance sample, the print job status is displayed each time a different print job is selected. This update is taken care of by the PrintJob_SelectionChanged method.

This example shows the PrintJob_SelectionChanged method in the PrintJobManagement.xaml.cs file. It shows how to display the status of a print job, based on an IPrintJob object.


private void PrintJob_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    try
    {
        // Display details of the selected print job.
        IPrintJob job = (IPrintJob)PrintJobListBox.SelectedItem;
        if (job != null)
        {
            PrintJobDetails.Text =
                "Details of print job: " + job.Name + "\r\n" +
                "Pages printed: " + job.PrintedPages + "/" + job.TotalPages + "\r\n" +
                "Submission time: " + job.SubmissionTime + "\r\n" +
                "Job status: " + DisplayablePrintJobStatus.ToString(job.Status);
        }
        else
        {
            PrintJobDetails.Text = "Please select a print job";
        }
    }
    catch (Exception exception)
    {
        rootPage.NotifyUser("Caught an exception: " + exception.Message, NotifyType.ErrorMessage);
    }
}


To help display the print job status description, the PrintJob_SelectionChanged method uses a static dictionary, named printJobStatusDisplayNames, to help display job status descriptions that are in a user-friendly text format.

This example shows the DisplayablePrintJobStatus class in the PrintJobManagement.xaml.cs file. This class contains the static members used by the PrintJob_SelectionChanged.


internal class DisplayablePrintJobStatus
{
    /// <summary>
    /// Converts the PrintJobStatus bit fields to a display string.
    /// </summary>
    internal static string ToString(PrintJobStatus printJobStatus)
    {
        StringBuilder statusString = new StringBuilder();

        // Iterate through each of the PrintJobStatus bits that are set and convert it to a display string.
        foreach (var printJobStatusDisplayName in printJobStatusDisplayNames)
        {
            if ((printJobStatusDisplayName.Key & printJobStatus) != 0)
            {
                statusString.Append(printJobStatusDisplayName.Value);
            }
        }

        int stringlen = statusString.Length;
        if (stringlen > 0)
        {
            // Trim the trailing comma from the string.
            return statusString.ToString(0, stringlen - 1);
        }
        else
        {
            // If no print job status field was set, display "Not available".
            return "Not available";
        }
    }

    /// <summary>
    /// Static constructor that initializes the display name for the PrintJobStatus field.
    /// </summary>
    static DisplayablePrintJobStatus()
    {
        printJobStatusDisplayNames = new Dictionary<PrintJobStatus, string>();

        printJobStatusDisplayNames.Add(PrintJobStatus.Paused, "Paused,");
        printJobStatusDisplayNames.Add(PrintJobStatus.Error, "Error,");
        printJobStatusDisplayNames.Add(PrintJobStatus.Deleting, "Deleting,");
        printJobStatusDisplayNames.Add(PrintJobStatus.Spooling, "Spooling,");
        printJobStatusDisplayNames.Add(PrintJobStatus.Printing, "Printing,");
        printJobStatusDisplayNames.Add(PrintJobStatus.Offline, "Offline,");
        printJobStatusDisplayNames.Add(PrintJobStatus.PaperOut, "Out of paper,");
        printJobStatusDisplayNames.Add(PrintJobStatus.Printed, "Printed,");
        printJobStatusDisplayNames.Add(PrintJobStatus.Deleted, "Deleted,");
        printJobStatusDisplayNames.Add(PrintJobStatus.BlockedDeviceQueue, "Blocked device queue,");
        printJobStatusDisplayNames.Add(PrintJobStatus.UserIntervention, "User intervention required,");
        printJobStatusDisplayNames.Add(PrintJobStatus.Restarted, "Restarted,");
        printJobStatusDisplayNames.Add(PrintJobStatus.Complete, "Complete,");
        printJobStatusDisplayNames.Add(PrintJobStatus.Retained, "Retained,");
    }
    
    /// <summary>
    /// Private constructor to prevent default instantiation.
    /// </summary>
    private DisplayablePrintJobStatus() { }

    /// <summary>
    /// Contains the mapping between PrintJobStatus fields and display strings.
    /// </summary>
    private static Dictionary<PrintJobStatus, string> printJobStatusDisplayNames;
}


Step 4: Cancel print job

Similar to displaying print job status, cancelling a print job is fairly straightforward when you have an IPrintJob object. The IPrintJob class provides a RequestCancel method that initiates the cancellation of the corresponding print job. This is demonstrated in the sample's CancelPrintJob_Click method.

This example shows the CancelPrintJob_Click method in the PrintJobManagement.xaml.cs file.


private void CancelPrintJob_Click(object sender, RoutedEventArgs e)
{
    try
    {
        IPrintJob job = (IPrintJob)PrintJobListBox.SelectedItem;
        job.RequestCancel();
    }
    catch (Exception exception)
    {
        rootPage.NotifyUser("Caught an exception: " + exception.Message, NotifyType.ErrorMessage);
    }
}


Testing

Before you can test your Windows Store device app, it must be linked to your printer using device metadata.

  • You need a copy of the device metadata package for your printer, to add the device app info to it. If you don’t have device metadata, you can build it using the Device Metadata Authoring Wizard as described in the topic Create device metadata for your Windows Store device app.

    Note  To use the Device Metadata Authoring Wizard, you must install Microsoft Visual Studio Professional 2013, Microsoft Visual Studio Ultimate 2013, or the standalone SDK for Windows 8.1, before completing the steps in this topic. Installing Microsoft Visual Studio Express 2013 for Windows installs a version of the SDK that doesn't include the wizard.

The following steps build your app and install the device metadata.

  1. Enable test signing.
    1. Start the Device Metadata Authoring Wizard from %ProgramFiles(x86)%\Windows Kits\8.1\bin\x86, by double-clicking DeviceMetadataWizard.exe
    2. From the Tools menu, select Enable Test Signing.
  2. Reboot the computer
  3. Build the solution by opening the solution (.sln) file. Press F7 or go to Build->Build Solution from the top menu after the sample has loaded.

  4. Disconnect and uninstall the printer. This step is required so that Windows will read the updated device metadata the next time the device is detected.
  5. Edit and save device metadata. To link the device app to your device, you must associate the device app with your device.

    Note  If you haven't created your device metadata yet, see Create device metadata for your Windows Store device app.

    1. If the Device Metadata Authoring Wizard is not open yet, start it from %ProgramFiles(x86)%\Windows Kits\8.1\bin\x86, by double-clicking DeviceMetadataWizard.exe.
    2. Click Edit Device Metadata. This will let you edit your existing device metadata package.
    3. In the Open dialog box, locate the device metadata package associated with your Windows Store device app. (It has a devicemetadata-ms file extension.)
    4. On the Specify Windows Store device app information page, enter the Windows Store app info in the Windows Store device app box. Click on Import Windows Store App manifest file to automatically enter the Package name, Publisher name, and Windows Store App ID.
    5. If your app is registering for printer notifications, fill out the Notification handlers box. In Event ID, enter the name of the print event handler. In Event Asset, enter the name of the file where that code resides.

    6. When you're done, click Next until you get to the Finish page.
    7. On the Review the device metadata package page, make sure that all of the settings are correct and select the Copy the device metadata package to the metadata store on the local computer check box. Then click Save.
  6. Reconnect your printer so that Windows reads the updated device metadata when the device is connected.

Related topics

Job Management (v4 Printer Driver)
Developing v4 print drivers
Bidirectional Communications
Getting started with Windows Store apps
Create a Windows Store device app (step-by-step guide)
Create device metadata for a Windows Store device app (step-by-step guide)

 

 

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