云母材料未出现在辅助 window 上

Question

I have a little problem with a multi-window UWP app.

I have the Mica material applied to my page and when I run my program, the first window shows with the Mica material. If I click on show second window, It pops up, but the background is in my system-accent-color, not the Mica material.

Here my code of MainPage.xaml:

<Page
    x:Class="MultiWindowTest.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:MultiWindowTest"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:muxc="using:Microsoft.UI.Xaml.Controls"
    muxc:BackdropMaterial.ApplyToRootOrPageBackground="True">

    <Grid>
        <Button Click="Button_Click" Content="New Window" HorizontalAlignment="Center" VerticalAlignment="Center"/>
    </Grid>
</Page>

MainPage.xaml.cs:

private async void Button_Click(object sender, RoutedEventArgs e)
{
    AppWindow appWindow = await AppWindow.TryCreateAsync();
    Frame appWindowContentFrame = new Frame();
    appWindowContentFrame.Navigate(typeof(MainPage));
    ElementCompositionPreview.SetAppWindowContent(appWindow, appWindowContentFrame);

    await appWindow.TryShowAsync();
}

Here is also an image, as you can see the first window has the Mica material and the second one is only colored in my Accent color:

Can someone explain this phenomenon? Or did I do something wrong? Or is it a bug from Microsoft?

Answer 1

Mica material not showing up on secondary window

It looks BackdropMaterial is not compatible with AppWindow , please go ahead post this in WinUI github, and currently there is a workaround that use ApplicationView to implement multiple views. And ApplicationView could show BackdropMaterial correctly in the second view.

CoreApplicationView newView = CoreApplication.CreateNewView();
int newViewId = 0;
await newView.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
    Frame frame = new Frame();
    frame.Navigate(typeof(MainPage), null);
    Window.Current.Content = frame;
    // You have to activate the window in order to show it later.
    Window.Current.Activate();

    newViewId = ApplicationView.GetForCurrentView().Id;
});
bool viewShown = await ApplicationViewSwitcher.TryShowAsStandaloneAsync(newViewId);

For more detail, please refer to document here .