Value converters – small pieces of code that are very useful in case of binding some values in XAML. Without them some types of bindings in XALM would not be so easy. We use them in Windows Phone, Silverlight or WPF projects. In most cases for each new project I copy the most important converters to solution. For me the most important are:

[list]

  • string / Uri to BitmapImage
  • bool to Visibility
  • Color to SolidColorBrush
  • String + StringFormat

[/list]

Please click more to see implementation of the following converters.

BitmapImageConverter

public class BitmapImageConverter : IValueConverter
{
  public object Convert(object value, Type targetType,
                        object parameter, CultureInfo culture)
  {
    string stringValue = value as string;
    if (stringValue != null)
    {
      return new BitmapImage(new Uri(stringValue, UriKind.RelativeOrAbsolute));
    }

    Uri uriValue = value as Uri;
    if (uriValue != null)
    {
      return new BitmapImage(uriValue);
    }

    throw new NotSupportedException();
  }

  public object ConvertBack(object value, Type targetType,
                            object parameter, CultureInfo culture)
  {
    throw new NotSupportedException();
  }
}

BooleanToVisibilityConverter

public class BooleanToVisibilityConverter : IValueConverter
{
  public object Convert(object value, Type targetType, 
                        object parameter, CultureInfo culture)
  {
    return value != null && (bool)value ? Visibility.Visible : Visibility.Collapsed;
  }

  public object ConvertBack(object value, Type targetType,
                            object parameter, CultureInfo culture)
  {
    return ((Visibility)value) == Visibility.Visible;
  }
}

ColorToBrushConverter

public class ColorToBrushConverter : IValueConverter
{
  public object Convert(object value, Type targetType, 
                        object parameter, CultureInfo culture)
  {
    if (value == null)
    {
      return new SolidColorBrush(Colors.Transparent);
    }

    if (value is Color)
    {
      return new SolidColorBrush((Color)value);
    }

    string stringValue = value as string;
    if (stringValue != null)
    {
      stringValue = stringValue.Replace("#", string.Empty);
      return new SolidColorBrush(Color.FromArgb(
        Byte.Parse(stringValue.Substring(0,2), NumberStyles.HexNumber),
        Byte.Parse(stringValue.Substring(2,2), NumberStyles.HexNumber),
        Byte.Parse(stringValue.Substring(4,2), NumberStyles.HexNumber),
        Byte.Parse(stringValue.Substring(6,2), NumberStyles.HexNumber)));
    }

    throw new NotSupportedException();
  }

  public object ConvertBack(object value, Type targetType, 
                            object parameter, CultureInfo culture)
  {
    throw new NotSupportedException();
  }
}

StringFormatConverter

public class StringFormatConverter : IValueConverter
{
  public object Convert(object value, Type targetType, 
                        object parameter, CultureInfo culture)
  {
    if (parameter == null && value == null)
    {
      return String.Empty;
    }

    return parameter == null ? value.ToString() 
        : String.Format(CultureInfo.CurrentCulture, parameter.ToString(), value);
  }

  public object ConvertBack(object value, Type targetType, 
                            object parameter, CultureInfo culture)
  {
    throw new NotSupportedException();
  }
}

Check it:

Default ThumbnailVeryfication of the signed XML document Default ThumbnailSerializableDictionary Default ThumbnailLINQ is not so bad Default ThumbnailStringFormat, XAML and Windows Phone