IValueConverter for visibility binding in WPF is never called

Question

I want to bind the visibility property of a control in WPF to a boolean value. I wrote a Converter based on IValueConverter:

namespace MyApp.Converter
{
    using System;
    using System.Windows.Data;

    public class BoolToVisibilityConverter : IValueConverter
    {
        public Object Convert(Object value, Type targetType, Object parameter, System.Globalization.CultureInfo culture)
        {            
            if ((Boolean)(value)==true)
            {
                return "Visible";
            }
            return "Collapsed";
        }

        public Object ConvertBack(Object value, Type targetType, Object parameter, System.Globalization.CultureInfo culture)
        {
            ...
        }
    }
}

And tried both: to define the converter in App.xaml and in the Window.Resources of the Window itself:

xmlns:Converters="clr-namespace:MyApp.Converter"
...
<Window.Resources>
    <Converters:BoolToVisibilityConverter x:Key="BoolToVisibilityConverter" />
</Window.Resources>

alternative in App.xaml:

xmlns:Converters="clr-namespace:MyApp.Converter"
...
<Application.Resources>
    <Converters:BoolToVisibilityConverter x:Key="BoolToVisibilityConverter" />
</Application.Resources>

Using the Converter for the visibility property compiles - but the converter is never called and thus the visibility never changes:

<Label Visibility="{Binding ShowCirle,  Converter={StaticResource BoolToVisibilityConverter}}"/>

The binding itself seems ok - since the output of ShowCircle in a label updates correctly:

<Label Content="{Binding ShowCircle}"></Label>

So, what am I missing? The build compiles without errors, starts, but the binding only updates the string (for debug purposes) but not the visibility - and a breakpoint in the converter itself is never hit.

Answer 1

Your converter should not return a string it should be Visiblity.Visible or Visibility.Collapsed.

To check if your Bindings are correct take a look at the Output-Window when debugging. If you see a Binding-Error (20,40 not sure which one) with your Property-Name then something is wrong with your binding. Maybe just a missspelling of the property.