Catel - Part 4 of n: Unit testing with Catel

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="EmptyStringToVisibilityConverter.cs" company="Catel development team">
//   Copyright (c) 2008 - 2011 Catel development team. All rights reserved.
// </copyright>
// <summary>
//   Convert from string to <see cref="System.Windows.Visibility" />.
//   If the string is not null or empty, Visibility.Visible will be returned.
//   If the string is null or empty, Visibility.Collapsed will be returned.
// </summary>
// --------------------------------------------------------------------------------------------------------------------

using System;
using System.Windows;
using System.Windows.Data;

namespace Catel.Windows.Data.Converters
{
    /// <summary>
    /// Convert from string to <see cref="System.Windows.Visibility"/>. 
    /// If the string is not null or empty, Visibility.Visible will be returned. 
    /// If the string is null or empty, Visibility.Collapsed will be returned.
    /// </summary>
#if !SILVERLIGHT
	[ValueConversion(typeof(string), typeof(Visibility))]
#endif
    public class EmptyStringToCollapsingVisibilityConverter : VisibilityConverterBase
    {
        #region Constructor & destructor
        /// <summary>
        /// Initializes a new instance of the <see cref="EmptyStringToCollapsingVisibilityConverter"/> class.
        /// </summary>
        public EmptyStringToCollapsingVisibilityConverter()
            : base(Visibility.Collapsed) { }

        /// <summary>
        /// Initializes a new instance of the <see cref="EmptyStringToCollapsingVisibilityConverter"/> class.
        /// </summary>
        /// <param name="notVisibleVisibility">The <see cref="Visibility"/> state when not visibible should be returned.</param>
        /// <exception cref="ArgumentException">when <paramref name="notVisibleVisibility"/> is <see cref="Visibility.Visible"/>.</exception>
        internal EmptyStringToCollapsingVisibilityConverter(Visibility notVisibleVisibility)
            : base(notVisibleVisibility) { }
        #endregion

        /// <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>
        /// <param name="culture">The culture to use in the converter.</param>
        /// <returns>
        /// 	<c>true</c> if the specified value is visible; otherwise, <c>false</c>.
        /// </returns>
        public override bool IsVisible(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            // Get parameter
            bool invert = ((parameter != null) && (parameter.GetType() == typeof(bool))) ? (bool)parameter : false;

            // Get value
            string stringValue = value as string;

            // Return right value
            if (invert)
            {
                return !string.IsNullOrEmpty(stringValue) ? false : true;
            }

            return string.IsNullOrEmpty(stringValue) ? false : true;
        }
    }

#if !SILVERLIGHT
	/// <summary>
	/// Convert from string to <see cref="System.Windows.Visibility"/>. 
	/// If the string is not null or empty, Visibility.Visible will be returned. 
	/// If the string is null or empty, Visibility.Hidden will be returned.
	/// </summary>
	[ValueConversion(typeof(string), typeof(Visibility))]
    public class EmptyStringToHidingVisibilityConverter : EmptyStringToCollapsingVisibilityConverter
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="EmptyStringToHidingVisibilityConverter"/> class.
        /// </summary>
	    public EmptyStringToHidingVisibilityConverter()
            : base(Visibility.Hidden) { }
    }
#endif
}