Manage Print Jobs

To pause or resume a print job or a print queue.

Windows Management Instrumentation allows you to retrieve a vast amount of system information using a query-like syntax. One of the tasks you can perform with WMI is to retrieve a list of outstanding print jobs, along with information about each one. You can also perform operations such as printing and resuming a job or all the jobs for a printer. In order to use WMI, you need to add a reference to the System.Management.dll assembly.

The following code shows a Windows-based application that interacts with the print queue. It performs a WMI query to get a list of all the outstanding jobs on the computer and displays the job ID for each one in a list box. When the user selects the item, a more complete WMI query is performed, and additional details about the print job are displayed in a text box. Finally, the user can click the Pause and Resume button after selecting a job to change its status.

using System;
using System.Windows.Forms;
using System.Management;
using System.Collections;

public class PrintQueueTest : System.Windows.Forms.Form {

    private System.Windows.Forms.ListBox lstJobs;
    private System.Windows.Forms.Button cmdRefresh;
    private System.Windows.Forms.TextBox txtJobInfo;
    private System.Windows.Forms.Button cmdPause;
    private System.Windows.Forms.Button cmdResume;
    private System.Windows.Forms.Label label1;
    private System.Windows.Forms.Label label2;

    // (Designer code omitted.)
    private void PrintQueueTest_Load(object sender, System.EventArgs e) {
    
        cmdRefresh_Click(null, null);
    }

    private void cmdRefresh_Click(object sender, System.EventArgs e) {
    
        // Select all the outstanding print jobs.
        string query = "SELECT * FROM Win32_PrintJob";
        ManagementObjectSearcher jobQuery = 
          new ManagementObjectSearcher(query);
        ManagementObjectCollection jobs = jobQuery.Get();

        // Add the jobs in the queue to the list box.
        lstJobs.Items.Clear();
        txtJobInfo.Text = "";
        foreach (ManagementObject job in jobs) {
            lstJobs.Items.Add(job["JobID"]);
        }
    }

    // This helper method performs a WMI query and returns the
    // WMI job for the currently selected list box item.
    private ManagementObject GetSelectedJob() {

        try {

            // Select the matching print job.
            string query = "SELECT * FROM Win32_PrintJob " +
              "WHERE JobID='" + lstJobs.Text + "'";
            ManagementObjectSearcher jobQuery = 
              new ManagementObjectSearcher(query);           
            ManagementObjectCollection jobs = jobQuery.Get();
            IEnumerator enumerator = jobs.GetEnumerator();
            enumerator.MoveNext();
            return (ManagementObject)enumerator.Current;

        }catch (InvalidOperationException){

            // the Current property of the enumerator is invalid
            return null;
        }
    }

    private void lstJobs_SelectedIndexChanged(object sender, 
      System.EventArgs e) {
    
        ManagementObject job = GetSelectedJob();
        if (job == null) {
            txtJobInfo.Text = "";
            return;
        }

        // Display job information.
        string jobInfo = "Document: " + job["Document"].ToString();
        jobInfo += Environment.NewLine;
        jobInfo += "DriverName: " + job["DriverName"].ToString();
        jobInfo += Environment.NewLine;
        jobInfo += "Status: " + job["Status"].ToString();            
        jobInfo += Environment.NewLine;
        jobInfo += "Owner: " + job["Owner"].ToString();

        jobInfo += Environment.NewLine;
        jobInfo += "PagesPrinted: " +
        job["PagesPrinted"].ToString();
        jobInfo += Environment.NewLine;
        jobInfo += "TotalPages: " + job["TotalPages"].ToString();

        if (job["JobStatus"] != null) {
            txtJobInfo.Text += Environment.NewLine;
            txtJobInfo.Text += "JobStatus: " + job["JobStatus"].ToString();
        }
        if (job["StartTime"] != null) {
            jobInfo += Environment.NewLine;
            jobInfo += "StartTime: " + job["StartTime"].ToString();
        }

        txtJobInfo.Text = jobInfo;
    }

    private void cmdPause_Click(object sender, System.EventArgs e) {
    
        if (lstJobs.SelectedIndex == -1) return;
        ManagementObject job = GetSelectedJob();
        if (job == null) return;
        
        // Attempt to pause the job.
       int returnValue = Int32.Parse( 
         job.InvokeMethod("Pause", null).ToString());

        // Display information about the return value.
        if (returnValue == 0) {
            MessageBox.Show("Successfully paused job.");

        }else {
            MessageBox.Show("Unrecognized return value when pausing job.");
        }
    }

    private void cmdResume_Click(object sender, System.EventArgs e) {
    
        if (lstJobs.SelectedIndex == -1) return;
        ManagementObject job = GetSelectedJob();
        if (job == null) return;
        
        if ((Int32.Parse(job["StatusMask"].ToString()) & 1) == 1) {
        
            // Attempt to resume the job.
            int returnValue = Int32.Parse(
              job.InvokeMethod("Resume", null).ToString());

            // Display information about the return value.
            if (returnValue == 0) {
                MessageBox.Show("Successfully resumed job.");

            }else if (returnValue == 5) {
                MessageBox.Show("Access denied.");

            }else {
                MessageBox.Show(
                  "Unrecognized return value when resuming job.");
            }
        }
    }
}

Remember that Windows permissions might prevent you from pausing or removing a print job created by another user. In fact, permissions might even prevent you from retrieving status information and could cause an exception to be thrown.

Technorati : C# Print Jobs Management