转换器属性 IValueConverter

演示如何使用参数 via 属性创建简单转换器，然后在声明中传递它。将 bool 值转换为 Visibility。通过将 Inverted 属性设置为 True 来允许反转结果值。

public class BooleanToVisibilityConverter : IValueConverter
{
    public bool Inverted { get; set; }

    /// <summary>
    /// Convert bool or Nullable bool to Visibility
    /// </summary>
    /// <param name="value">bool or Nullable bool</param>
    /// <param name="targetType">Visibility</param>
    /// <param name="parameter">null</param>
    /// <param name="culture">null</param>
    /// <returns>Visible or Collapsed</returns>
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        bool bValue = false;
        if (value is bool)
        {
            bValue = (bool)value;
        }
        else if (value is Nullable<bool>)
        {
            Nullable<bool> tmp = (Nullable<bool>)value;
            bValue = tmp ?? false;
        }

        if (Inverted)
            bValue = !bValue;
        return (bValue) ? Visibility.Visible : Visibility.Collapsed;
    }

    /// <summary>
    /// Convert Visibility to boolean
    /// </summary>
    /// <param name="value"></param>
    /// <param name="targetType"></param>
    /// <param name="parameter"></param>
    /// <param name="culture"></param>
    /// <returns>True or False</returns>
    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (value is Visibility)
        {
            return ((Visibility) value == Visibility.Visible) && !Inverted;
        }

        return false;
    }
}

使用转换器

1. 命名空间

xmlns:converters="clr-namespace:MyProject.Converters;assembly=MyProject"

2. 定义资源

<converters:BooleanToVisibilityConverter x:Key="BoolToVisibilityInvertedConverter"
                                         Inverted="False"/>

3. 在绑定中使用它

<Button Visibility="{Binding AllowEditing, Converter={StaticResource BoolToVisibilityConverter}}"/>