Search code examples
wpfwindows.net-5windows-11

Minimize window using Windows 11 animation effect

There are two (it would seem) idiomatic ways to minimize a WPF window in code:

  • window.WindowState = window.WindowState.Minimized
  • SystemCommands.MinimizeWindow(window)

The desired behavior is that the windows 11 window minimize animation is seen. The actual behavior is that the window instantly disappears from the screen.

Please note: This is for a window with a custom chrome - therefore triggering the behavior from code seems necessary:

<Window
    WindowStyle="None"
    AllowTransparency="True
    Background="Transparent">

    <!-- custom windows chrome here  -->

</Window>

Is this a defect in the WPF desktop pack for .NET 5 (and 6)?

How does one not get the desired behavior without reverting back to default windows with standard chrome? It is not an option to use a WinUI 3.0 window since XAML islands have not been released yet and gradual modernization is needed.

There are some proposed solutions on the web, like:

And the other (old) stackoverflow question:

However, I could not get it to work with a window with a transparent background.

===== update after issue was closed =====

Reviewer: please read this carefully before voting to close the issue again and point to exact workable solution.

Issues with existing answers:

  • First suggestion is to change WindowStyle, then WindowState; this poses a problem since it requires AllowTransparency=false which defeats the purpose of the exercise here - which is getting a custom chrome.

  • Other suggestion is to use Win32 API's. Again I tried to do that but it did not work in my setting. I haven't logged the exact error messages I got though. However, looking at the code again there is an obvious issue with it: it has the same window requirement as the first suggestion: the window must not be transparent - observe code from the old answer:

    private IntPtr WindowProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    if (msg == ApiCodes.WM_SYSCOMMAND)
    {
        if (wParam.ToInt32() == ApiCodes.SC_MINIMIZE)
        {
            WindowStyle = WindowStyle.SingleBorderWindow;
            WindowState = WindowState.Minimized;
            handled = true;
        }
        else if (wParam.ToInt32() == ApiCodes.SC_RESTORE)
        {
            WindowState = WindowState.Normal;
            WindowStyle = WindowStyle.None;
            handled = true;
        }
    }
    return IntPtr.Zero;
}
Solution

  • It seems to be on the roadmap in Themes of .NET for .NET 7:

    Also this amazing piece of open-source just landed:

    • WPF UI - Windows 11 styles and controls for WPF