CODEWITHSUNDEEP
wpf
user1094821
user1094821

Reputation: 1845

Starting a WPF application as hidden

I'm writing a WPF application and want it to start as a hidden window. I've created the Window object and set its Visibility property to Visibility.Hidden before calling Application.Run(). Then, I have an event handler for Window.Loaded that also sets the visibility to Visibility.Hidden. Between the call to Application.Run() and the callback to OnWindowLoaded(), there is a black outline of the window that flashes up on the screen and then disappears. It's like the window manager is creating a drop shadow for the window or something and then hides it immediately.

After running my project through instrumentation, I finally found that Window.Show() was somehow getting called. So, I looked into the source code at http://www.dotnetframework.org/Search.aspx:

I then looked at the source for System.Windows.Window:

Based on this, I don't see how to force the window to stay hidden. By trying to make the window invisible at startup, I'm causing the Application object to call Window.Show(); I don't understand why the Application object even cares about the window's visibility. It's been a frustrating experience... :-(

I've seen other answers that say to not call Application.Run() and to instead set up your own event dispatchers, but that seems like overkill for something that should be easy. I just want the main window to stay hidden, for no "flicker" to appear at app startup, and for the window to become visible when I'm ready for it to do so (which happens later in my application logic).

Can anyone offer a suggestion?

Upvotes: 3

Views: 2941

Answers (2)

Morten Brudvik
Morten Brudvik

Reputation: 479

The comment on this Answer finally led me to find the solution to this issue. I needed to display multiple windows on multiple screens at once, and by minimizing the window it gives me the performance I needed. Thanks.

Upvotes: 1

feO2x
feO2x

Reputation: 5728

Did you remove the StartupUri entry in App.xaml? If you do, the App class won't instantiate the window for you and show it. You can do this by yourself by overwriting the App.OnStartup method.

Basically, I build a composition root in this OnStartup method and just create a window at the end of the process:

    protected override void OnStartup(StartupEventArgs e)
    {
        base.OnStartup(e);

        // Do your custom initialization code here

        MainWindow = new MainWindow();
        MainWindow.Show();
    }

If you really want to omit the whole application build up process (which I wouldn't recommend, as you won't have features like the fallback to Application Resources), you can create a Dispatcher by yourself using this code:

var dispatcher = Dispatcher.CurrentDispatcher;
var synchronizationContext = new DispatcherSynchronizationContext(dispatcher);
SynchronizationContext.SetSynchronizationContext(synchronizationContext);
Dispatcher.Run();

Upvotes: 4

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