MVVM # Episode 1

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

namespace Views
{
    /*
     * This source file contains all the converters used.
     */


    /// <summary>
    /// Returns false if the object is null, true otherwise.
    /// handy for using when something needs to be enabled or disabled depending on
    /// whether a value has been selected from a list.
    /// </summary>
    [ValueConversion(typeof(object), typeof(bool))]
    public class NullToFalseBooleanConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return (value != null);
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return null;
        }

    }

    /// <summary>
    /// Returns false if the object is null, true otherwise.
    /// handy for using when something needs to be enabled or disabled depending on
    /// whether a value has been selected from a list.
    /// </summary>
    [ValueConversion(typeof(object), typeof(Visibility))]
    public class NullToHiddenVisibilityConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value == null)
            {
                return Visibility.Hidden;
            }
            else
            {
                return Visibility.Visible;
            }
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return null;
        }

    }
}