Hook ValueChanged
event of slider and there you can do animation based on new and old value of slider.
XAML:
<Slider x:Name="mySlider" DockPanel.Dock="Bottom"
Height="30" Width="250"
Value="1" Maximum="3" Minimum="0"
ValueChanged="mySlider_ValueChanged" />
Code behind:
private void mySlider_ValueChanged(object sender,
RoutedPropertyChangedEventArgs<double> e)
{
if (e.NewValue > 2 && e.OldValue <= 2)
{
DoubleAnimation fadeOutAnimation = new DoubleAnimation(0.0,
new Duration(TimeSpan.FromSeconds(1)));
myRectangle.BeginAnimation(Rectangle.OpacityProperty, fadeOutAnimation);
}
else if(e.NewValue < 2 && e.OldValue >= 2)
{
DoubleAnimation fadeInAnimation = new DoubleAnimation(1.0,
new Duration(TimeSpan.FromSeconds(1)));
myRectangle.BeginAnimation(Rectangle.OpacityProperty, fadeInAnimation);
}
}