Shaker/Avalonia/ShakerApp/Views/LEDControl.axaml

<UserControl
    x:Class="ShakerApp.LEDControl"
    xmlns="https://github.com/avaloniaui"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    d:DesignHeight="450"
    d:DesignWidth="450"
    mc:Ignorable="d">
    <Viewbox Stretch="Fill">
        <Grid
            Width="56"
            Height="56"
            Margin="0"
            HorizontalAlignment="Center"
            VerticalAlignment="Center">
            <Ellipse
                Width="46"
                Height="46"
                HorizontalAlignment="Center"
                VerticalAlignment="Center">
                <Ellipse.Fill>
                    <RadialGradientBrush Center="50% 50%" GradientOrigin="50% 50%">
                        <GradientStop Offset="0" Color="{Binding $parent[UserControl].Foreground, Converter={StaticResource BrushToColorConverter}, ConverterParameter=10}" />
                        <GradientStop Offset="0.7" Color="{Binding $parent[UserControl].Foreground, Converter={StaticResource BrushToColorConverter}, ConverterParameter=180}" />
                        <GradientStop Offset="1" Color="{Binding $parent[UserControl].Foreground, Converter={StaticResource BrushToColorConverter}}" />
                    </RadialGradientBrush>
                </Ellipse.Fill>
            </Ellipse>
            <Ellipse
                Width="56"
                Height="56"
                HorizontalAlignment="Center"
                VerticalAlignment="Center"
                Fill="Transparent"
                Stroke="{Binding $parent[UserControl].Foreground}"
                StrokeThickness="2" />
        </Grid>
    </Viewbox>
</UserControl>