这是一个自动执行淡出、切换值、淡入的实现
使用（将 xmlns:l 设置为正确的命名空间后：
Label l:AnimatedSwitch.Property="Content" l:AnimatedSwitch.Binding="{Binding SomeProp}"/>
代码（这是概念验证代码，没有错误处理，还没有准备好生产）。
public class AnimatedSwitch : DependencyObject
{
// Define the attached properties
public static DependencyProperty BindingProperty =
DependencyProperty.RegisterAttached("Binding", typeof(object), typeof(AnimatedSwitch),
new PropertyMetadata(BindingChanged));
public static DependencyProperty PropertyProperty =
DependencyProperty.RegisterAttached("Property", typeof(string), typeof(AnimatedSwitch));
public static object GetBinding(DependencyObject e)
{
return e.GetValue(BindingProperty);
}
public static void SetBinding(DependencyObject e, object value)
{
e.SetValue(BindingProperty, value);
}
public static string GetProperty(DependencyObject e)
{
return (string)e.GetValue(PropertyProperty);
}
public static void SetProperty(DependencyObject e, string value)
{
e.SetValue(PropertyProperty, value);
}
// When the value changes do the fadeout-switch-fadein
private static void BindingChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
Storyboard fadeout = new Storyboard();
var fadeoutAnim = new DoubleAnimation(){To=0,Duration=new Duration(TimeSpan.FromSeconds(0.3))};
Storyboard.SetTarget(fadeoutAnim,d);
Storyboard.SetTargetProperty(fadeoutAnim, new PropertyPath("Opacity"));
fadeout.Children.Add(fadeoutAnim);
fadeout.Completed += (d1, d2) =>
{
d.GetType().GetProperty(GetProperty(d)).SetValue(d, GetBinding(d), null);
Storyboard fadein = new Storyboard();
var fadeinAnim = new DoubleAnimation() { To = 1, Duration = new Duration(TimeSpan.FromSeconds(0.3)) };
Storyboard.SetTarget(fadeinAnim, d);
Storyboard.SetTargetProperty(fadeinAnim, new PropertyPath("Opacity"));
fadein.Children.Add(fadeinAnim);
fadein.Begin();
};
fadeout.Begin();
}
}