Creating a window from a new thread in WPF app with no main window

Question

I'm working on a WPF application that has no main window (it runs in the notification area using code from http://www.codeproject.com/KB/WPF/wpf_notifyicon.aspx).

In the App.xaml.cs, I've created a new thread which runs some monitoring code that returns a custom collection of alerts. The collection has a render() method which I planned to use to show a window with the alert information in them, but I can't figure out how to accomplish it. I'd be grateful for any input.

Code samples below:

App.xaml:

<Application x:Class="DowntimeReportMonitor.Views.Icon.App"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         Startup="Application_Startup"
         Exit="Application_Exit">
<Application.Resources>
    <ResourceDictionary>
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="IconDictionary.xaml" />
        </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
</Application.Resources>
</Application>

App.xaml.cs

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Threading;
using System.Windows;

using Hardcodet.Wpf.TaskbarNotification;

using DowntimeReportMonitor.Core;

namespace DowntimeReportMonitor.Views.Icon
{
/// <summary>
/// Interaction logic for App.xaml
/// </summary>
public partial class App : Application
{
    private TaskbarIcon _taskbaricon;

    private AlertWorker _alertWorker;
    private Thread _alertWorkerThread;

    /// <summary>
    /// Event handler for Application startup
    /// </summary>
    /// <param name="sender">The event sender</param>
    /// <param name="e">Event arguments</param>
    private void Application_Startup(object sender, StartupEventArgs e)
    {
        // Create and start a new TaskbarIcon.
        this._taskbaricon = (TaskbarIcon)FindResource("notificationIcon");

        // Create and start a new AlertWorker.
        this._alertWorker = new AlertWorker();
        this._alertWorkerThread = new Thread(this._alertWorker.doWork);
        this._alertWorkerThread.SetApartmentState(ApartmentState.STA);
        this._alertWorkerThread.Start();
    }



    /// <summary>
    /// Event handler for Application exit
    /// </summary>
    /// <param name="sender">The event sender</param>
    /// <param name="e">Event arguments</param>
    private void Application_Exit(object sender, ExitEventArgs e)
    {
        // Stop the alert worker.
        this._alertWorker.requestStop();
        this._alertWorkerThread.Join();

        // Dispose of the notification icon.
        this._taskbaricon.Dispose();
    }
}
}

AlertWorker.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

using DowntimeReportMonitor.Core;

namespace DowntimeReportMonitor.Views.Icon
{
class AlertWorker
{
    private volatile bool _stopRequested;

    private ReportMonitor _reportMonitor;

    public AlertWorker()
    {
        _reportMonitor = new ReportMonitor(new wpfRenderableReportAlertCollection());
    }

    public void doWork()
    {
        while (!_stopRequested)
        {
            this._reportMonitor.monitorReports().render();

            Thread.Sleep(30000);
        }
    }

    public void requestStop()
    {
        this._stopRequested = true;
    }
}
}

Answer 1

Well, first of all, you need a dedicated UI thread. Usually it's the initial application thread, but you can take any. (It must be an STA thread.)

Next, you start a dispather in that thread (Dispatcher.CurrentDispatcher.Run).

Next, you can post commands to that thread using Dispatcher.Invoke or Dispatcher.BeginInvoke.

Finally, you can post to your thread window.Show for your custom Window class.