C# ClickOnce SingleInstance project - how ?

Question

I want to create a program that uses ClickOnce for installation and registers a file-association, and always only starts a single instance, so that if a file of that file extension is clicked again it will be sent to the first (already opened) program.

Does anybody know of a good code-example of how to do that ?

Please keep in mind the ClickOnce part - because that changes how one should handle the SingleInstance bit.

Answer 1

I guess this will help you: http://www.openwinforms.com/single_instance_application.html

Answer 2

You could do something similar to this:

using System.Diagnostics;

    namespace Foo

    {

        class Bar

        {

            static void Main(string[] args)

            {

                Process p = Process.GetCurrentProcess();

                Process [] processSearch = Process.GetProcessesByName(p.ProcessName);

                if (processSearch.Length > 1)

                {

                    return;

                }

            }
         }
    }

Answer 3

You should use a Mutex to check if you application is running:

    static void Main()
    {
        bool createdNew;

        using (Mutex mutex = new Mutex(true, Application.ProductName, out createdNew))
        {
            mutex.ReleaseMutex();
            if (createdNew)
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new FormMain());
            }
            else
            {
                using (Process currentProcess = Process.GetCurrentProcess())
                {
                    foreach (Process process in Process.GetProcessesByName(currentProcess.ProcessName))
                    {
                        if (process.Id != currentProcess.Id)
                        {
                            User32.SetForegroundWindow(process.MainWindowHandle);
                            break;
                        }
                    }
                }
            }
        }
    }

The SetForegroundWindow:

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool SetForegroundWindow(IntPtr hWnd);

Answer 4

Same question over here: http://stackoverflow.com/questions/248721/

Try this on: http://northhorizon.net/2010/single-instance-clickonce/