Determine Light or Dark Theme with WP7

Determine Light or Dark Theme with WP7

Visibility v = (Visibility)Resources["PhoneLightThemeVisibility"];
  
 if (v == System.Windows.Visibility.Visible)
 {
     ImageBrush ib = new ImageBrush();
     Uri u = new Uri("PanoramaBack2.png", UriKind.Relative);
     ib.ImageSource = new System.Windows.Media.Imaging.BitmapImage(u);
     PanoramaControl.Background = ib;
 }

Any time you use a background image you can check the
PhoneLightThemeVisibility resource and switch between different versions of the
image to provide the best experience with either Black or White text.

http://mobileworld.appamundi.com/blogs/peterfoot/archive/2010/09/17/determine-light-or-dark-theme-with-wp7-rtm.aspx