（C#）WPF:LinearGradientBrush 线性渐变画刷和RadialGradientBrush 圆形渐变画刷

<Window x:Class="WpfApp1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
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"
xmlns:local="clr-namespace:WpfApp1"
mc:Ignorable="d"
Title="MainWindow" Height="" Width="">
<Grid VerticalAlignment="Center" HorizontalAlignment="Center">
<Ellipse Width="" Height="">
<Ellipse.Fill>
<RadialGradientBrush GradientOrigin="0.25,0.25" RadiusX="0.75" RadiusY="0.75">
<RadialGradientBrush.GradientStops>
<GradientStop Color="White" Offset="" />
<GradientStop Color="Black" Offset="0.65" />
<GradientStop Color="Gray" Offset="0.8" />
</RadialGradientBrush.GradientStops>
</RadialGradientBrush>
</Ellipse.Fill>
</Ellipse>
</Grid>
</Window>