xml code
---------------------------------------------------
<Page
    x:Class="MyApp.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:MyApp"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    
 
    <Grid>
        <Grid.Resources>
            <Storyboard x:Key="std" x:Name="std" RepeatBehavior="Forever" AutoReverse="True">
                <DoubleAnimation Storyboard.TargetName="scltrf" Storyboard.TargetProperty="ScaleX" Duration="0:0:2" From="1" To="2"/>
                <DoubleAnimation Storyboard.TargetName="scltrf" Storyboard.TargetProperty="ScaleY" Duration="0:0:2" From="1" To="2"/>
            </Storyboard>
        </Grid.Resources>
        <Ellipse Width="150" Height="150" Fill="SkyBlue" HorizontalAlignment="Center" VerticalAlignment="Center" RenderTransformOrigin="0.5,0.5">
            <Ellipse.RenderTransform>
                <ScaleTransform x:Name="scltrf"/>
            </Ellipse.RenderTransform>
        </Ellipse>
    </Grid>
</Page>
 
 
C# code
------------------------------------------------------------------
 public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
 
            this.NavigationCacheMode = NavigationCacheMode.Required;
        }
 
        /// <summary>
在此页将要在
        /// </summary>
        /// <param name="e">描述如何访问此页的事件数据。
此参数通常用于配置页。</param>
        protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            this.std.Begin();
        }
    }