[2.0] Win32 Handles From VB6 to C#

[Kuranes]

Hi everyone. I'm encountering a roadblock with a VB6/C# integration project which I'm hoping someone will have a solution or workaround for.

Basic Synopsis: I have an existing program written entirely in VB6, and I'm (unsuccessfully) trying to use the VB6 program to open a modal wizard dialog programmed in C#, but I'm unable to pass to the C# application the appropriate Win32 handle of the VB6 application (to make the VB6 program the "owner") and as such the C# program does not run in modal mode.


In my VB6 application, I call the C# application using a Shell command:

Private Sub mnuImport_Click()
   Shell App.Path & "\ImportWizard.exe " & Me.hWnd, vbNormalFocus
End Sub

The Main() of the C# project takes in the hWnd argument and passes it on to the main form:

[ STAThread ]
static void Main(string[] args)
{
   Application.EnableVisualStyles();
   Application.SetCompatibleTextRenderingDefault(false);

   if (args.Length > 0)
   {
      long hWnd = Convert.ToInt64(args[0]);
      Application.Run(new frmWizard(hWnd));
   }
   else
   {
      Application.Run(new frmWizard());
   }
}

Finally, in the constructor of the main form that accepts a long value, I attempt to open the form as a modal dialog, which is where the roadblock is:

public frmWizard(long handle)
{
   InitializeComponent();
   this.ShowDialog(handle); //doesn't work
}

Basically, my problem is: the ShowDialog() method only accepts an IWin32Window object, and the only reference to the VB6 window I can give is the value passed from the hWnd property. It seems as though ShowDialog() will only accept a Win32 handle from a form which implements the IWin32Window interface, in which case I may be in trouble.

Any ideas/feedback would be greatly appreciated.

Thanks.

[Kuranes]

I found a solution that seems to work.

I created a wrapper class which inherits from IWin32Window with a single constructor which takes in an IntPtr value and a read-only property that returns the properly wrapped handle of the window.

This makes the C# window a modal child of the VB6 parent form.

    
class WindowWrapper : System.Windows.Forms.IWin32Window 
    {
        private IntPtr _hWnd;
        
        public WindowWrapper(IntPtr handle)
        {
            _hWnd = handle;
        }

        public IntPtr Handle
        {
            get
            {
                return _hWnd;
            }
        }
    }

Then the wizard form constructor I modified thusly:

public frmWizard(long handle)
{
   InitializeComponent();
   IntPtr parent = new IntPtr(handle);
   this.ShowDialog(new WindowWrapper(parent)); //works
}

This solution I got from CodeProject.