RSS-reader that keeps unread items - windows-phone-7

Question

So I have a simple RSS-reader, that has a feed that gets updated when the app is started. How can I add functionality that keeps the new unread items in a different color? I would like to make it visible for the user which posts are new since last time he/she opened the app.

Answer 1

Presuming you have a model something like;
public class RSSItem {
public bool IsUnread { get; set; }
public string Title { get; set; }
}
You'll want to bind the ForegroundColor of a TextBlock to your IsUnread property using a IValueConverter that takes a bool and returns a Color. So your XAML might look like;
<phone:PhoneApplicationPage.Resources>
<converters:UnreadForegroundConverter x:Key="UnreadForegroundConverter" />
</phone:PhoneApplicationPage.Resources>
<ListBox x:Name="RSSItems">
<DataTemplate>
<TextBlock Text="{Binding Title}" Foreground="{Binding IsUnread, Converter={StaticResource UnreadForegroundConverter}}" />
</DataTemplate>
</ListBox>
Don't forget to add the xmlns:converters attribute to your Page's tag.
You'll then want to implement your IValueConverter to do the boolean to colour conversion;
public class UnreadForegroundConverter : IValueConverter {
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) {
if ((bool)value == true) {
return Application.Current.Resources["PhoneAccentColor"];
}
return Application.Current.Resources["PhoneForegroundColor"];
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) {
throw new NotImplementedException();
}
}
And obviously you'll need to bind the listbox, RSSItems, to a collection of RSSItem. Eg.
ObservableCollection<RSSItem> items = new ObservableCollection<RSSItem>();
// populate items somehow
RSSItems.ItemsSource = items;
Hope that helps.