WPF BooleanToVisibilityConverter that converts to Hidden instead of Collapsed when false?

I've found the simplest and best solution to be this:

[ValueConversion(typeof(bool), typeof(Visibility))]
public sealed class BoolToVisibilityConverter : IValueConverter
{
  public Visibility TrueValue { get; set; }
  public Visibility FalseValue { get; set; }

  public BoolToVisibilityConverter()
  {
    // set defaults
    TrueValue = Visibility.Visible;
    FalseValue = Visibility.Collapsed;
  }

  public object Convert(object value, Type targetType, 
      object parameter, CultureInfo culture)
  {
    if (!(value is bool))
      return null;
    return (bool)value ? TrueValue : FalseValue;    
  }

  public object ConvertBack(object value, Type targetType, 
      object parameter, CultureInfo culture)
  {
    if (Equals(value, TrueValue))
      return true;
    if (Equals(value, FalseValue))
      return false;
    return null;
  }
}

When using it, just configure a version that does exactly what you need it to in XAML like this:

<Blah.Resources>
  <local:BoolToVisibilityConverter
         x:Key="BoolToHiddenConverter"
         TrueValue="Visible" FalseValue="Hidden" />
</Blah.Resources>

Then use it in one or more bindings like this:

<Foo Visibility="{Binding IsItFridayAlready, 
                          Converter={StaticResource BoolToHiddenConverter}}" />

This simple solution addresses hidden/collapsed preferences as well as reversing/negating the effect.

SILVERLIGHT USERS must drop the [ValueConversion] declaration as that attribute is not part of the Silverlight framework. It's not strictly needed in WPF either, but is consistent with built-in converters.


Unfortunately, it only converts to Visible or Collapsed, so you'll have to write your own. Here is the Convert method according to Reflector:

public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
    bool flag = false;
    if (value is bool)
    {
        flag = (bool)value;
    }
    else if (value is bool?)
    {
        bool? nullable = (bool?)value;
        flag = nullable.HasValue ? nullable.Value : false;
    }
    return (flag ? Visibility.Visible : Visibility.Collapsed);
}

Can you not just use a style instead of a converter? The code would be something like:

<Style x:Key="Triggers" TargetType="Button">
    <Style.Triggers>
    <Trigger Property="{Binding ...}" Value="false">
        <Setter Property = "Visibility" Value="Hidden"/>
    </Trigger>
    </Style.Triggers>
</Style>

You'll need to provide the property binding yourself to point to your bool property.