（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>

效果图：