Creating a background application with WPF

Thomas Claudius Huber · August 22, 2015

Creating a background application with WPF

By Thomas Claudius Huber 36 Comments

Sometimes you need to have an application running in the background. Then you don’t want your MainWindow to be visible all the time. Instead you just want to have an icon in the notification area that allows the user to open up the MainWindow and to exit the application. In WPF you can do this easily with the help of Windows Forms’ NotifyIcon-class.

Just add references to System.Windows.Forms and System.Drawing to your WPF-project. Add also an icon-file (.ico) to your project resources. To do this just open the Resources.resx-file in the Properties-folder of your project. Select the Icon-resource and click the Add Resource button. I’ve named it MyIcon.

Then go to the App.xaml.cs and implement it like below. The trick is to never close the MainWindow, as a closed Window cannot be shown again. Instead cancel the closing and just hide it.

using System.ComponentModel;
using System.Windows;
 
namespace BackgroundApplication
{
 
    public partial class App : Application
    {
        private System.Windows.Forms.NotifyIcon _notifyIcon;
        private bool _isExit;
 
        protected override void OnStartup(StartupEventArgs e)
        {
            base.OnStartup(e);
            MainWindow = new MainWindow();
            MainWindow.Closing += MainWindow_Closing;
 
            _notifyIcon = new System.Windows.Forms.NotifyIcon();
            _notifyIcon.DoubleClick += (s, args) => ShowMainWindow();
            _notifyIcon.Icon = BackgroundApplication.Properties.Resources.MyIcon;
            _notifyIcon.Visible = true;
 
            CreateContextMenu();
        }
 
        private void CreateContextMenu()
        {
            _notifyIcon.ContextMenuStrip =
              new System.Windows.Forms.ContextMenuStrip();
            _notifyIcon.ContextMenuStrip.Items.Add("MainWindow...").Click += (s, e) => ShowMainWindow();
            _notifyIcon.ContextMenuStrip.Items.Add("Exit").Click += (s, e) => ExitApplication();
        }
 
        private void ExitApplication()
        {
            _isExit = true;
            MainWindow.Close();
            _notifyIcon.Dispose();
            _notifyIcon = null;
        }
 
        private void ShowMainWindow()
        {
            if (MainWindow.IsVisible)
            {
                if (MainWindow.WindowState == WindowState.Minimized)
                {
                    MainWindow.WindowState = WindowState.Normal;
                }
                MainWindow.Activate();
            }
            else
            {
                MainWindow.Show();
            }
        }
 
        private void MainWindow_Closing(object sender, CancelEventArgs e)
        {
            if (!_isExit)
            {
                e.Cancel = true;
                MainWindow.Hide(); // A hidden window can be shown again, a closed one not
            }
        }
    }
}

Now go in addition to the App.xaml and remove the Startup-Uri, so that when you start the application, only the NotifyIcon is added to the notification area

<Application x:Class="BackgroundApplication.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:BackgroundApplication">
  <Application.Resources>
         
    </Application.Resources>
</Application>

Done

Download the sample-project here: Background application

Creating a background application with WPF

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