Pass arguments to running application

Question

I am making an image uploader (upload image to image hosting website) and I'm having some issues passing an argument (image location to an already running application)

• First of all let's say MyApp.exe is always running
• Whenever I right click on an image I have added an item in the default windows context menu that says "Upload image".
• When that's clicked it needs to pass the location to the already running application.

My program.cs:

static class Program
{
    [DllImport("user32.dll")]
    static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

    [DllImport("user32.dll")]
    static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, UIntPtr
    wParam, IntPtr lParam);

    [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
    static extern uint RegisterWindowMessage(string lpString);

    [STAThread]
    static void Main(params string[] Arguments)
    {
        if (Arguments.Length > 0)
        {
    //This means that the the upload item in the context menu is clicked
    //Here the method "uploadImage(string location)"
    //of the running application must be ran
        }
        else
        {
    //just start the application
            Application.Run(new ControlPanel());
        }
    }
}

Note that the ControlPanel class doesn't have a visible form, only a tray icon is present since a form is not needed.

Could I get any help on how to do this?

Answer 1

I have figured it out, so awesome thanks for the person who posted the http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/a5bcfc8a-bf69-4bbc-923d-f30f9ecf5f64 link, this is exactly what I was looking for!

Here's a the full solution:

static class Program
{
    [STAThread]
    static void Main(params string[] Arguments)
    {
        SingleInstanceApplication.Run(new ControlPanel(), NewInstanceHandler);
    }

    public static void NewInstanceHandler(object sender, StartupNextInstanceEventArgs e)
    {
        string imageLocation = e.CommandLine[1];
        MessageBox.Show(imageLocation);
        e.BringToForeground = false;
        ControlPanel.uploadImage(imageLocation);
    }

    public class SingleInstanceApplication : WindowsFormsApplicationBase
    {
        private SingleInstanceApplication()
        {
            base.IsSingleInstance = true;
        }

        public static void Run(Form f, StartupNextInstanceEventHandler startupHandler)
        {
            SingleInstanceApplication app = new SingleInstanceApplication();
            app.MainForm = f;
            app.StartupNextInstance += startupHandler;
            app.Run(Environment.GetCommandLineArgs());
        }
    }  
}

Thanks alot all, and especially the person who posted that link I mentioned above but I guess he deleted his answer?

Regards, Kenny

Answer 2

Well you will have to establish a communication channel for other applications to post the images to. This communication channel can be one of the following - not a complete list just samples:

• A directory that is watched by your app and the file is added once it is added to the directory.
• A port where other applications can send information to.
• A self-hosted web service that accepts the images.
• A TCP port that receives the images.
• A named pipe.
• ....

As you see there are several possibilities. The right one for you depends on your scenario. The file system is an option that can be implemented easily using a FileSystemWatcher for a sample see here.

A self-hosted web sevice exposes a web service that can receive images. See here for a sample.

IMHO, these are the two options that are easiest. But ... there are several more.

For the TCP port see Tim's post.