Question

I want to show a different icon/image depending on an enum value. For example, if I had the following enum:

  public enum UploadStatus
  {
      Unknown = 0,
      WaitingToUpload = 10,
      Uploading = 20,
      Uploaded = 30,
      UploadFailed = 40
  }

I’d like to write XAML that looks something like this:

...

<EnumImage Value="{Binding Path=CurrentStatus}">
  <EnumImageItem Value="Unknown"         Image="/images/unknown.png" />
  <EnumImageItem Value="WaitingToUpload" Image="/images/clock.png" />
  <EnumImageItem Value="Uploading"       Image="/images/upload.png" />
  <EnumImageItem Value="Uploaded"        Image="/images/tick.png" />
  <EnumImageItem Value="UploadFailed"    Image="/images/error.png" />
</EnumImage>

...

I’ve found many posts suggesting custom IValueConverters, but those solutions don’t fit the XAML paradigm.

Any pointers or suggestions?

Answer 1

Here is a Value converter which maintains the “XAML paradigm” that is the relationship between enum values and images is maintained in XAML.

[ContentProperty("Items")]
public class EnumToObjectConverter : IValueConverter
{
    public ResourceDictionary Items { get; set; }

    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        string key = Enum.GetName(value.GetType(), value);
        return Items[key];
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException("This converter only works for one way binding");
    }
}

Note that this is very generic it actually maps values of any enum type to any arbitary object. This is what its usage looks like in Xaml:-

<Grid.Resources>
  <local:EnumToObjectConverter x:Key="Icons">
    <ResourceDictionary>
 <BitmapImage x:Key="Unknown" UriSource="/images/unknown.png" />
      <BitmapImage x:Key="WaitingToUpload" UriSource="/images/clock.png" />        
      <BitmapImage x:Key="Uploading"       UriSource="/images/upload.png" />        
      <BitmapImage x:Key="Uploaded"        UriSource="/images/tick.png" />        
      <BitmapImage x:Key="UploadFailed"    UriSource="/images/error.png" />        
    </ResourceDictionary>
  </local:EnumToObjectConverter>
</Grid.Resources>

This converter can be used when binding property of the enum type:-

 <Image Source="{Binding Status, Converter={StaticResource Icons}}" />