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.