How can I bring the main WPF window to the front?

Question

How do maximize and bring a WPF mainwindow to the front of my desktop? I have a filewatcher monitoring a directory. If a new file is created in the directory I want to bring my WPF apps main window to the front of the dekstop. As you can see I have tried several methods on the mainwidnow.

Modified Code: (I am getting the following error: "The calling thread cannot access this object because a different thread owns it")

DispatcherOperation o =  Dispatcher.CurrentDispatcher.BeginInvoke(new 
Action(delegate
        {

            var win = System.Windows.Application.Current.MainWindow;
            win.Activate();
            win.WindowState = System.Windows.WindowState.Normal;
            win.Topmost = true;
            win.Focus();


        }), System.Windows.Threading.DispatcherPriority.ContextIdle, null);

        Debug.WriteLine("Invoke");

        o.Wait();

Modified 2 (Tried getting the dispatcher of the main window. I still get " "The calling thread cannot access this object because a different thread owns it".

 System.Windows.Application.Current.MainWindow.Dispatcher.Invoke(() =>
    {
        var win = System.Windows.Application.Current.MainWindow;
        win.Activate();
        win.WindowState = System.Windows.WindowState.Normal;
        win.Topmost = true;
        win.Focus();
    }, DispatcherPriority.Normal);

UPDATE (Working) I guess I was not calling the dispatcher tied to the mainwindow with the above examples. I ended up creating a variable called _mainWindow of type MainWindow in the window class. In the MainWindow constructor I instantiated the variable: _mainwidow = this;

Then I pass the _mainwindow variable in the constructor of the class where I use the FileWatcher. Here I can access the dispatcher of the _mainwindow variable:

        _mainWindow.Dispatcher.Invoke(() =>
        {
            var win = System.Windows.Application.Current.MainWindow;
            win.Activate();
            win.WindowState = System.Windows.WindowState.Normal;
            win.Topmost = true;
            win.Focus();
        }, DispatcherPriority.Normal);

Does [this](https://stackoverflow.com/a/4831839/23074) answer help? — Eric Olsson, Jun 28 '17 at 20:35
Does it work when you use the `Dispatcher` of the main window instead of the current one? — Streamline, Jun 29 '17 at 13:18
Streamline, I tried getting the Dispatcher of the main window by changing my code. See Modified 2 above. I still get "The calling thread cannot access this object because a different thread owns it". — Bill Greer, Jun 29 '17 at 13:33

score 1 · Accepted Answer · answered Jun 29 '17 at 03:01

1

Try this code

 Dispatcher.Invoke(() =>
            {
                this.Activate();
                this.WindowState = System.Windows.WindowState.Normal;
                this.Topmost = true;
                this.Focus(); 
            });

answered Jun 29 '17 at 03:01

Justin CI

2,693
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I am using Dispatcher.CurrentDispatcher.BeginInvoke as it seems like Dispatcher.Invoke is not available in .Net 4.6. Also, "this" does not work for me in my method, so I grabbed a reference to the MainWindow. I am now getting the following error when I try to get a reference to the Window: "The calling thread cannot access this object because a different thread owns it" See my modified code above. – Bill Greer Jun 29 '17 at 12:29

How can I bring the main WPF window to the front?

1 Answers1