Question

I’ve failed certification because I have an image that’s all white. So when a user switches to the light theme it fails because you can’t see it. How do I swap this imaged based on the theme applied?

Thank you in advance

Answer 1

In XAML

<Image Source="{Binding ImageSource}" />

In the view model that contains property ImageSource

public string ImageSource
{
  get
  {
    if( (Visibility)App.Current.Resources["PhoneDarkThemeVisibility"] 
      == Visibility.Visible ) {
        return "/path/to/dark/image.png";

    } else {
        return "/path/to/light/image.png";

    }
  }
  private set {}
}

This may not change the picture if the user tombstones your app, changes the theme and switches back to the app.

One way to handle that scenario is to cache the current theme setting in the App class constructor, then compare it with the current setting within App.Application_Activated, if they’re different you’ll need to somehow indicate that the above view model needs to fire a property changed notification for ImageSource.