Avalonia/samples/ControlCatalog/Pages/NavigationPage/NavigationPageCurvedHeaderPage.xaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="ControlCatalog.Pages.NavigationPageCurvedHeaderPage">

  <DockPanel>
    <ScrollViewer x:Name="InfoPanel" DockPanel.Dock="Right" Width="300">
      <StackPanel Margin="16" Spacing="16">

        <TextBlock Text="Curved Header Shop App" FontSize="16" FontWeight="SemiBold"
                   Foreground="{DynamicResource SystemControlHighlightAccentBrush}" />

        <TextBlock TextWrapping="Wrap" FontSize="12" Opacity="0.7"
                   Text="A dome-header pattern using a StreamGeometry clip updated on SizeChanged to give the nav bar area its elliptical bottom curve. The avatar floats at the dome tip, straddling the header/content boundary." />

        <Separator />

        <TextBlock Text="Key Techniques" FontSize="13" FontWeight="SemiBold" />
        <StackPanel Spacing="4">
          <TextBlock FontSize="12" TextWrapping="Wrap" Text="• Dome: StreamGeometry ArcTo on SizeChanged" />
          <TextBlock FontSize="12" TextWrapping="Wrap" Text="• Avatar: Canvas overlay, centered at dome Y" />
          <TextBlock FontSize="12" TextWrapping="Wrap" Text="• Home: SetHasNavigationBar(page, false)" />
          <TextBlock FontSize="12" TextWrapping="Wrap" Text="• Profile: BarLayoutBehavior.Overlay (transparent bar)" />
          <TextBlock FontSize="12" TextWrapping="Wrap" Text="• Tap a featured card or recommended item to open the profile page" />
        </StackPanel>

        <Separator />

        <TextBlock Text="API Notes" FontSize="13" FontWeight="SemiBold" />
        <TextBlock TextWrapping="Wrap" FontSize="12" Opacity="0.7"
                   Text="The curved shape is achieved entirely in page content: no NavigationPage API changes needed. A future per-page SetBarBackground(page, brush) API would allow the Overlay back-button foreground to be driven by the page theme rather than the global NavigationBarForeground resource." />


      </StackPanel>
    </ScrollViewer>

    <Border BorderBrush="{DynamicResource SystemControlForegroundBaseMediumLowBrush}"
            BorderThickness="1" CornerRadius="8" ClipToBounds="True">
      <NavigationPage x:Name="NavPage"
                      Background="#f6f7f8">
        <NavigationPage.Resources>
          <SolidColorBrush x:Key="NavigationBarBackground" Color="Transparent" />
          <SolidColorBrush x:Key="NavigationBarForeground" Color="White" />
        </NavigationPage.Resources>
      </NavigationPage>
    </Border>
  </DockPanel>

</UserControl>