<Button x:Class="UI.btn.ZButton"

             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

             mc:Ignorable="d"

                 xmlns:i="http://schemas.microsoft.com/xaml/behaviors" xmlns:btn="clr-namespace:UI.btn"

        d:DesignHeight="450" d:DesignWidth="800" Cursor="Hand">

    <Button.Template>

        <ControlTemplate  TargetType="Button" >

            <Grid ClipToBounds="True" Background="{TemplateBinding Background}" MouseLeftButtonDown="Grid_MouseLeftButtonDown"  >

                <Border>

                    <ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" Content="{TemplateBinding Content}"  >

                    </ContentPresenter>

                </Border>

                <Path Fill="Black" x:Name="MyPath">

                    <Path.Data>

                        <EllipseGeometry x:Name="MyEllip" Center="{Binding MyProperty}"   RadiusX="0" RadiusY="{Binding RelativeSource={RelativeSource Mode=Self},Path=RadiusX}">

                        </EllipseGeometry>

                    </Path.Data>

                </Path>

            </Grid>

        </ControlTemplate>

    </Button.Template>

</Button>

private void Grid_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)

        {

         var target=Template.FindName("MyEllip", this) as EllipseGeometry;

            target.Center = Mouse.GetPosition(this);

            var animation = new DoubleAnimation()

            {

                From=0,

                To=150,

                Duration=new Duration(TimeSpan.FromSeconds(1))

            };

            target.BeginAnimation(EllipseGeometry.RadiusXProperty, animation);

            var animation2 = new DoubleAnimation()

            {

                From = 0.3,

                To = 0,

                Duration = new Duration(TimeSpan.FromSeconds(1))

            };

            var target2= Template.FindName("MyPath",this) as Path;

            target2.BeginAnimation(Path.OpacityProperty, animation2);

        }