Compile a Visual Studio C# project for two TargetPlatformVersion

Question

I developed a .NET windows application which worked both on Windows 7 and 8.1. Then I added the Toast notification feature that came with Windows 8 (from this question: How can I use the Windows.UI namespace from a regular (Non-Store) Win32 .NET application? ). This also worked, I just had to add:

<PropertyGroup> <TargetPlatformVersion>8.0</TargetPlatformVersion> </PropertyGroup>

to the project file.

As I referenced the Windows.winmd file from the Windows 8.1 SDK C:\\Program Files (x86)\\Windows Kits\\8.1\\References\\CommonConfiguration\\Neutral\\Windows.winmd , the executable does not start on Windows 7 anymore! I double-click and that's it. No errors, no messages.

As I did not find any solution online, that's where my question comes up: How do I manage to do both: Offer the toast feature to my users AND make the same .exe run on Windows 7 ?

Thank you in advance!

EDIT It turns out that though TargetPlatformVersion is set to 8.0, the executable starts on Windows 7 anyway, but crashes as soon as the program tries to load the Windows 8 libraries:

An unhandled exception of type 'System.TypeLoadException' occurred in ToastTester.exe. Additional information: Could not find Windows Runtime type 'Windows.UI.Notifications.ToastNotificationManager'.

on line Application.Run(new Form1());

In Form1.cs in line 9 I've got using Windows.UI.Notifications;

What is the best way to avoid this exception during runtime, even though it is expected that this executable will run in environments like Windows 7 where the Windows.UI.Notifications namespace is definitely not available?

Answer 1

I designed my own workaround for being able to support Windows 8 toasts and at the same time prevent application crashes due to missing libraries when running on Windows 7. Note: I am using the Singleton design pattern (member INSTANCE ), but you can always do it otherwise.

ShellLink.cs is taken from here

Win8Toaster.cs:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Windows.Data.Xml.Dom;
using Windows.UI.Notifications;

namespace ToastManager
{
    class Win8Toaster
    {
        public const string APPUSERMODELID = "YourCompany.YourApplicationName";
        public static string ShortcutLocation;
        public static ToastNotifier ToastNotifier;

        private static Win8Toaster _INSTANCE = null;
        public static Win8Toaster INSTANCE
        {
            get
            {
                if (_INSTANCE == null)
                {
                    _INSTANCE = new Win8Toaster();
                }
                return _INSTANCE;
            }
        }

        public Win8Toaster()
        {
            ShortcutLocation = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + @"\Microsoft\Windows\Start Menu\Programs\YourCompany\YourApplication.lnk");
            //We need a start menu shortcut (a ShellLink object) to show toasts.
            if (!File.Exists(ShortcutLocation))
            {
                string directory = Path.GetDirectoryName(ShortcutLocation);
                if (!Directory.Exists(directory))
                {
                    Directory.CreateDirectory(directory);
                }
                using (ShellLink shortcut = new ShellLink())
                {
                    shortcut.TargetPath = System.Reflection.Assembly.GetEntryAssembly().Location;
                    shortcut.Arguments = "";
                    shortcut.AppUserModelID = APPUSERMODELID;
                    shortcut.Save(ShortcutLocation);
                }
            }
            ToastNotifier = ToastNotificationManager.CreateToastNotifier(APPUSERMODELID);
        }

        public void ShowToast(ToastContent Content)
        {
            XmlDocument ToastContent = new XmlDocument();
            ToastContent.LoadXml("<toast><visual><binding template=\"ToastImageAndText02\"><image id=\"1\" src=\"file:///" + Content.ImagePath + "\"/><text id=\"1\">" + Content.Text1 + "</text><text id=\"2\">" + Content.Text2 + "</text></binding></visual></toast>");
            ToastNotification thisToast = new ToastNotification(ToastContent);
            ToastNotifier.Show(thisToast);
        }                
    }
}

Toaster.cs

using System;
using System.Collections.Generic;
using System.Windows.Forms;

namespace ToastManager
{
    public static class Toaster
    {
        private static Win8Toaster ActiveToaster;
        public static bool Win8ToasterAvailable = true;
        public static void ShowToast(ToastContent Content)
        {
            if (Win8ToasterAvailable)
            {
                if (ActiveToaster == null)
                {
                    if (Environment.OSVersion.Version.Major > 6 || Environment.OSVersion.Version.Major == 6 && Environment.OSVersion.Version.Minor >= 2)
                    {
                        try
                        {
                            ActiveToaster = Win8Toaster.INSTANCE;
                        }
                        catch (Exception ex)
                        {
                            Win8ToasterAvailable = false;
                        }
                    }
                    else
                    {
                        Win8ToasterAvailable = false;
                    }
                }
                ActiveToaster.ShowToast(Content);
            }
            else
            {
                //Use alternative notifications because Windows 8 Toasts are not available
            }
        }
    }
    //I also wrote my own toast content structure:
    public class ToastContent
    {

        public string ImagePath, Text1, Text2;
        public ToastContent(string ImagePath, string Text1, string Text2)
        {
            this.ImagePath = ImagePath;
            this.Text1 = Text1;
            this.Text2 = Text2;
        }
    }
}

Now that you've got the necessary classes, here is how to use it (pretty simple, huh?):

ToastManager.Toaster.ShowToast(new ToastManager.ToastContent(@"..\path\toyour\image.png", "Your Application Name", "Time: " + DateTime.Now.ToLongTimeString()));

This example shows a toast notification with the current system time or nothing if you are on Windows 7.

A design suggestion:

I used WinForms to design a notification window which looks similar to that in Windows 8 and simulates the same functions, just with my own forms. Alternatively you can also implement a tray icon and show some notification bubbles.