PulsatingRectangle.xaml

<!-- =====================================================
      PulsatingRectangle.xaml (c) 2006 by Charles Petzold 
     ===================================================== -->
<Canvas xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <Rectangle Name="rect"
               Canvas.Left="96" Canvas.Top="96" 
               Width="192" Height="192"
               Stroke="Black">
        <Rectangle.Fill>
           <LinearGradientBrush x:Name="brush">
                <LinearGradientBrush.GradientStops>
                    <GradientStop Offset="0" Color="Red" />
                    <GradientStop Offset="1" Color="Blue" />
                </LinearGradientBrush.GradientStops>
            </LinearGradientBrush>
        </Rectangle.Fill>
    </Rectangle>

    <Canvas.Triggers>
        <EventTrigger RoutedEvent="Canvas.Loaded">
            <BeginStoryboard>
                <Storyboard>
                    <DoubleAnimation Storyboard.TargetName="rect"
                                     Storyboard.TargetProperty="Width"
                                     From="192" To="204" Duration="0:0:0.1"
                                     AutoReverse="True"
                                     RepeatBehavior="Forever" />

                    <DoubleAnimation Storyboard.TargetName="rect"
                                     Storyboard.TargetProperty="Height"
                                     From="192" To="204" Duration="0:0:0.1"
                                     AutoReverse="True"
                                     RepeatBehavior="Forever" />

                    <DoubleAnimation Storyboard.TargetName="rect"
                                     Storyboard.TargetProperty="(Canvas.Left)"
                                     From="96" To="90" Duration="0:0:0.1"
                                     AutoReverse="True"
                                     RepeatBehavior="Forever" />

                    <DoubleAnimation Storyboard.TargetName="rect"
                                     Storyboard.TargetProperty="(Canvas.Top)"
                                     From="96" To="90" Duration="0:0:0.1"
                                     AutoReverse="True"
                                     RepeatBehavior="Forever" />

                    <PointAnimation Storyboard.TargetName="brush"
                                    Storyboard.TargetProperty="StartPoint"
                                    From="0 0" To="1 0" Duration="0:0:5"
                                    AutoReverse="True"
                                    RepeatBehavior="Forever" />

                    <PointAnimation Storyboard.TargetName="brush"
                                    Storyboard.TargetProperty="EndPoint"
                                    From="1 1" To="0 1" Duration="0:0:5"
                                    AutoReverse="True"
                                    RepeatBehavior="Forever" />

                    <ColorAnimation 
                        Storyboard.TargetName="brush"
                        Storyboard.TargetProperty="GradientStops[0].Color"
                        From="Red" To="Blue" Duration="0:0:1" 
                        AutoReverse="True"
                        RepeatBehavior="Forever" />

                    <ColorAnimation 
                        Storyboard.TargetName="brush"
                        Storyboard.TargetProperty="GradientStops[1].Color"
                        From="Blue" To="Red" Duration="0:0:1" 
                        AutoReverse="True"
                        RepeatBehavior="Forever" />
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </Canvas.Triggers>
</Canvas>