AdaptiveImage.cs

namespace CustomControls
{
    public class AdaptiveImage : ContentControl
    {
        public static readonly DependencyProperty SourceProperty = DependencyProperty.Register(
            "Source",
            typeof(AdaptiveImageSource),
            typeof(AdaptiveImage),
            new PropertyMetadata(null, OnSourceChanged));

        public AdaptiveImageSource Source
        {
            get { return this.GetValue(SourceProperty) as AdaptiveImageSource; }
            set { this.SetValue(SourceProperty, value); }
        }

        private static void OnSourceChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
        {
            // TODO
        }
    }
}