#region Using directives

using System;
using System.Collections.ObjectModel;
using System.Windows.Forms;

using Microsoft.VisualBasic.ApplicationServices;

#endregion

namespace SingleMDISample {
  public class SingleMDIApplication : WindowsFormsApplicationBase {

    private static SingleMDIApplication application;
    internal static SingleMDIApplication Application {
      get {
        if( application == null ) {
          application = new SingleMDIApplication();
        }
        return application;
      }
    }
    
    // Must call base constructor to ensure correct initial 
    // WindowsFormsApplicationBase configuration
    public SingleMDIApplication() : base() {
      
      // This ensures the underlying single-SDI framework is employed, 
      // and OnStartupNextInstance is fired
      this.IsSingleInstance = true;
    }

    // Load MDI parent form and first MDI child form
    protected override void OnCreateMainForm() {
      this.MainForm = new MDIParentForm();
      this.CreateMDIChildWindow(this.CommandLineArgs);
    }

    // Load subsequent MDI child form
    protected override void OnStartupNextInstance(StartupNextInstanceEventArgs e) {
      this.CreateMDIChildWindow(e.CommandLine);
    }

    private void CreateMDIChildWindow(ReadOnlyCollection<string> args) {
      // Get file name, if provided
      string fileName = (args.Count > 0 ? args[0] : null);
      
      // Ask MDI parent to create a new MDI child and open
      // file, if one was passed
      ((MDIParentForm)this.MainForm).CreateMDIChildWindow(fileName);
    }
  }
}