Proper way to ask if a Window is open in WPF

Question

I have this click event in my main window to open a new window

private void Button_Click(object sender, RoutedEventArgs e)
{
    cm = new CanalesMain();

    cm.Show();

    cm.Canales.setValues();

}

My cm variable is defined as a member class in my main window because I need to load/refresh the setValues() method every 5 minutes (there's a TimeSpan and a EventHandler for that)

The thing is, in my "refresh data" method I have this if statement to ask if the cm variable is loaded and is not null (I mean, if the window was ever opened or if is opened, ask if isn't closed)

if (cm!=null && cm.IsLoaded)
{
    cm.Canales.setValues();
}

Is this the correct or best way to ask if my window is open?

Answer 1

Strictly speaking no, it's not the right way. IsLoaded doesn't mean that Window is visible, just loaded (even if this may be equivalent in most of scenarios but it means this window has been created once, it has a handle, no mention to its visibility).

What you have to check is the Visibility property (it's what, finally, Show() will change), it'll be Visible if the Window is currently visible or Hidden if it has not been loaded (or it has been loaded and it still is but actually hidden).

To summarize:

if (cm != null && cm.Visibility == Visibility.Visible)
{
}

Please note that if Window is visible then it's implicit it has been loaded (it has a handle) but it's not true the vice-versa (a loaded window may not be visible and maybe it was even not in the past).

Answer 2

There is another way of checking which Windows are currently active:

foreach (Window window in Application.Current.Windows)
{ 
    // Check for your Window here
}

If your Window is of a particular type, then you can do this instead:

foreach (Window window in Application.Current.Windows.OfType<YourWindow>())
{ 
    // Do something with your Window here
}

Your Window will not appear here before it is displayed.