/// <summary>
/// Determines what value this converter should return.
/// </summary>
/// <param name="value">The value produced by the binding source.</param>
/// <param name="targetType">The type of the binding target property.</param>
/// <param name="parameter">The converter parameter to use.</param>
/// <returns>
/// <c>true</c> if the specified value is visible; otherwise, <c>false</c>.
/// </returns>
protected override bool IsVisible(object value, Type targetType, object parameter)
{
bool invert = ConverterHelper.ShouldInvert(parameter);
return(invert ? (value == null) : (value != null));
}
