<Grid Width="300" Height="460">

         <Grid.RowDefinitions>

             <RowDefinition Height="*"/>

             <RowDefinition Height="60"/>

             <RowDefinition Height="100"/>

         </Grid.RowDefinitions>

         <Grid.Triggers>

             <EventTrigger SourceName="btnStart" RoutedEvent="Button.Click">

                 <BeginStoryboard x:Name="myImageBStoryboard"  >

                     <Storyboard CurrentTimeInvalidated="Storyboard_CurrentTimeInvalidated">

                         <DoubleAnimation Storyboard.TargetName="myImageB" Storyboard.TargetProperty="Opacity" From="1" To="0" Duration="00:00:05">

                         </DoubleAnimation>

                     </Storyboard>

                 </BeginStoryboard>

             </EventTrigger>

             <EventTrigger SourceName="btnPause" RoutedEvent="Button.Click">

                 <PauseStoryboard BeginStoryboardName="myImageBStoryboard"></PauseStoryboard>

             </EventTrigger>

             <EventTrigger SourceName="btnResume" RoutedEvent="Button.Click">

                 <ResumeStoryboard BeginStoryboardName="myImageBStoryboard"></ResumeStoryboard>

             </EventTrigger>

             <EventTrigger SourceName="btnStop" RoutedEvent="Button.Click">

                 <StopStoryboard BeginStoryboardName="myImageBStoryboard"></StopStoryboard>

             </EventTrigger>

             <EventTrigger SourceName="btnMiddle" RoutedEvent="Button.Click">

                 <SeekStoryboard BeginStoryboardName="myImageBStoryboard" Offset="00:00:02">

                 </SeekStoryboard>

             </EventTrigger>

         </Grid.Triggers>

         <Grid Grid.Row="0" Grid.Column="0"  >

             <Image x:Name="myImageA" Source="Images/A.jpg"  Height="300" Width="300" Stretch="Fill"></Image>

             <Image x:Name="myImageB" Source="Images/B.jpg"   Height="300" Width="300"  Stretch="Fill" ></Image>

         </Grid>

         <StackPanel Grid.Row="1" Grid.Column="0" Orientation="Horizontal">

             <Button x:Name="btnStart" Content="Start" Width="50" Height="40"  Margin="3" ></Button>

             <Button x:Name="btnPause" Content="Pause" Width="50" Height="40" Margin="3" ></Button>

             <Button x:Name="btnResume" Content="Resume" Width="50" Height="40" Margin="3" ></Button>

             <Button x:Name="btnStop" Content="Stop" Width="50" Height="40" Margin="3" ></Button>

             <Button x:Name="btnMiddle" Content="SeekToMiddle" Width="50" Height="40" Margin="3" ></Button>

         </StackPanel>

         <StackPanel Grid.Row="2" Grid.Column="0" Orientation="Vertical">

             <TextBlock x:Name="myTextBlock" FontSize="13" Foreground="Red"> </TextBlock>

             <ProgressBar x:Name="myProgressBar"  Height="35" Background="White" Width="300" >

                 <ProgressBar.Foreground>

                     <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">

                         <GradientStop Color="#FF4DF22F" Offset="0.505" />

                         <GradientStop Color="#FFEFF5F1" Offset="1" />

                         <GradientStop Color="#FFF8F8F8" Offset="0.013" />

                     </LinearGradientBrush>

                 </ProgressBar.Foreground>

             </ProgressBar>

         </StackPanel>

     </Grid>

 public partial class MainWindow : Window

     {

         public MainWindow()

         {

             InitializeComponent();

         }

         private void Storyboard_CurrentTimeInvalidated(object sender, EventArgs e)

         {

             Clock storyboardClock = sender as Clock;

             if (storyboardClock.CurrentProgress != null)

             {

                 myTextBlock.Text = storyboardClock.CurrentTime.ToString();

                 myProgressBar.Value = (double)storyboardClock.CurrentProgress*;(注意这儿storyboardClock.CurrentProgres值范围是0至1)

                 System.Diagnostics.Debug.WriteLine(myProgressBar.Value);

             }

             else

             {

                 myProgressBar.Value = ;

                 myTextBlock.Text = "Stopped";

             }

         }

     }