<Window x:Class="Animation.ImageWipe"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="ImageWipe" Height="300" Width="300"
    >

  <Grid>
    <Grid.RowDefinitions>
      <RowDefinition></RowDefinition>
      <RowDefinition Height="Auto"></RowDefinition>

    </Grid.RowDefinitions>
    <Grid>
      <Image Source="night.jpg"></Image>
      <Image Source="day.jpg" Name="imgDay">
        <Image.OpacityMask>
          <LinearGradientBrush StartPoint="0,0" EndPoint="1,0">
            <GradientStop Offset="0" Color="Transparent" x:Name="transparentStop" />
            <GradientStop Offset="0" Color="Black" x:Name="visibleStop" />
          </LinearGradientBrush>
        </Image.OpacityMask>
      </Image>
    </Grid>
    
      <Button Name="cmdStart" Grid.Row="1" Padding="5" Margin="5">
        Start
        <Button.Triggers>
          <EventTrigger SourceName="cmdStart" RoutedEvent="Button.Click">
            <BeginStoryboard> 
              <Storyboard>
                <DoubleAnimation
                    Storyboard.TargetName="transparentStop"
                    Storyboard.TargetProperty="Offset" BeginTime="0:0:0.2" 
                    From="0" To="1" Duration="0:0:1" ></DoubleAnimation>
                <DoubleAnimation
                    Storyboard.TargetName="visibleStop"
                    Storyboard.TargetProperty="Offset"
                    From="0" To="1.2" Duration="0:0:1.2" ></DoubleAnimation>
              </Storyboard>
            </BeginStoryboard>
          </EventTrigger>

        </Button.Triggers>
      </Button>
      

    
    
  </Grid>
</Window>
