Programatically WPF Fade In (via extension methods)

Answer 1

Sounds like you're looking for something like this:

public static T FadeIn<T>(this T uiElement, int durationInSeconds)
{
  return uiElement.FadeFromTo(0, 1, durationInSeconds, false);
}
public static T FadeOut<T>(this T uiElement, int durationInSeconds)
{
  return uiElement.FadeFromTo(1, 0, durationInSeconds, false);
}

public static T FadeFromTo<T>(this T uiElement,
                              double fromOpacity, double toOpacity,
                              int durationInSeconds, bool loopAnimation)
where T : UIElement
{
  return (T)uiElement.wpfInvoke(()=>
  {
    var doubleAnimation =
      new DoubleAnimation(fromOpacity, toOpacity,
                          new Duration(TimeSpan.FromSeconds(durationInSeconds)));
    if(loopAnimation)
      doubleAnimation.RepeatBehavior = RepeatBehavior.Forever;
    uiElement.BeginAnimation(UIElement.OpacityProperty, doubleAnimation);
    return uiElement;
   });
}