winform application to launch and read from a file with custom extension

Question

I am building a windows forms application using C# that needs to get launched when a user clicks on a file with custom extension(eg. filename.mycustomextension) I plan to put a url in the filename.mycustomextension file. when user clicks on this file, we winform application should launch and also read contents of this file. Is it possible to do this?

Answer 1

First and most obviously you'll need to associate the file extension with the application either by "open with" in the shell, through an installer or directly in the registry.

MSDN - Best Practices for File Associations

Then from there it's really pretty simple.

   static class Program
    {    
        [STAThread]
        static void Main()
        {
            string[] args = Environment.GetCommandLineArgs(); 
            string text = File.ReadAllText(args[1]);

            // ...
        }
    }

• args[0] is the application path.
• args[1] will be the file path.
• args[n] will be any other arguments passed in.

Offhand I can't find any examples that show all of this together simply but Scott Hanselman has a nice example of loading files through a single instance WinForms application, about the same...

http://www.hanselman.com/blog/CommentView.aspx?guid=d2f676ea-025b-4fd6-ae79-80b04a34f24c

Answer 2

Yes, it is possible.

The idea is that when your application is clicked, you modify the registry key, to associate the extension file with your application.

Here are the sketches:

1. Use the FileAssociation class from here.
2. Initialize it, set all the parameters.

Here is an example:

            var FA = new FileAssociation();
            FA.Extension = "blah";
            FA.ContentType = "application/blah";
            FA.FullName = "blah Project File";
            FA.ProperName = "blahFile";
            FA.AddCommand("open", string.Format("\"{0}\" \"%1\"", System.Reflection.Assembly.GetExecutingAssembly().Location));
            //"C:\\mydir\\myprog.exe %1");
            FA.IconPath = System.Reflection.Assembly.GetExecutingAssembly().Location;
            FA.IconIndex = 0;
            FA.Create();