WPF 分享一种背景动画效果

<Window x:Class="WPFSamplesTest.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:WPFSamplesTest"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800"  >
    
    <Window.Triggers>
        <EventTrigger RoutedEvent="Page.Loaded">
            <BeginStoryboard Name="backgroundAnimationsBeginStoryboard">
                <Storyboard >
                    <ColorAnimation 
            Storyboard.TargetName="mainPanel"
            Storyboard.TargetProperty="(DockPanel.Background).(DrawingBrush.Drawing).(DrawingGroup.Children)[0].(GeometryDrawing.Brush).(SolidColorBrush.Color)"
            From="LightGray" To="DarkGray" Duration="0:0:50" RepeatBehavior="Forever" 
            AutoReverse="True"/>
                    <DoubleAnimation 
            Storyboard.TargetName="mainPanel"
            Storyboard.TargetProperty="(DockPanel.Background).(DrawingBrush.Transform).(RotateTransform.Angle)"
            From="0" To="360" Duration="0:5:00" RepeatBehavior="Forever" 
            AutoReverse="True"/>
                    <DoubleAnimation 
            Storyboard.TargetName="mainPanel"
            Storyboard.TargetProperty="(DockPanel.Background).(DrawingBrush.Drawing).(DrawingGroup.Children)[1].(GeometryDrawing.Geometry).(EllipseGeometry.RadiusX)"
            From="0.1" To="0.25" Duration="0:0:5" RepeatBehavior="Forever" 
            AutoReverse="True"/>
                    <PointAnimation 
            Storyboard.TargetName="mainPanel"
            Storyboard.TargetProperty="(DockPanel.Background).(DrawingBrush.Drawing).(DrawingGroup.Children)[2].(GeometryDrawing.Geometry).(EllipseGeometry.Center)"
            From="-0.25, -0.25" To="1.25,1.25" Duration="0:0:10" RepeatBehavior="Forever" 
            AutoReverse="True"/>
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
        
    </Window.Triggers>
    <Grid x:Name="mainPanel"  >
        <Grid.Background>
            <DrawingBrush TileMode="Tile"
        Viewport="0,0,100,100" ViewportUnits="Absolute">
                <DrawingBrush.Drawing>
                    <DrawingGroup>
                        <DrawingGroup.Children>

                            <GeometryDrawing>
                                <GeometryDrawing.Geometry>
                                    <RectangleGeometry Rect="0,0,1,1" />
                                </GeometryDrawing.Geometry>
                                <GeometryDrawing.Brush>
                                    <SolidColorBrush Color="LightGray" />
                                </GeometryDrawing.Brush>
                                <GeometryDrawing.Pen>
                                    <Pen Thickness="0.01" Brush="DarkGray" />
                                </GeometryDrawing.Pen>
                            </GeometryDrawing>

                            <GeometryDrawing Brush="#99CCCCCC">
                                <GeometryDrawing.Geometry>
                                    <EllipseGeometry Center="0.75,0.5" RadiusX="0.25" RadiusY="0.25" />
                                </GeometryDrawing.Geometry>
                            </GeometryDrawing>
                            <GeometryDrawing Brush="#66CCCCCC">
                                <GeometryDrawing.Geometry>
                                    <EllipseGeometry Center="0.25,0.25" RadiusX="0.1" RadiusY="0.1" />
                                </GeometryDrawing.Geometry>
                            </GeometryDrawing>
                        </DrawingGroup.Children>
                    </DrawingGroup>
                </DrawingBrush.Drawing>
                <DrawingBrush.Transform>
                    <RotateTransform CenterX="0.5" CenterY="0.5" />
                </DrawingBrush.Transform>
            </DrawingBrush>
        </Grid.Background>
       
    </Grid>
</Window>