WPF Trigger based on Object Type

Solution 1:

This is based on @AndyG's answer but is a bit safer because it's strongly typed.

Implement an IValueConverter named DataTypeConverter, which accepts an object and returns its Type (as a System.Type):

public class DataTypeConverter:IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, 
      CultureInfo culture)
    {
        return value?.GetType() ?? Binding.DoNothing;
    }

    public object ConvertBack(object value, Type targetType, object parameter,
      CultureInfo culture)
    {
       throw new NotImplementedException();
    }
}

Change your DataTrigger to use the Converter, and set the value to the Type:

<DataTrigger Binding="{Binding SelectedItem,  
      Converter={StaticResource DataTypeConverter}}" 
      Value="{x:Type local:MyType}">
...
</DataTrigger>

Declare DataTypeConverter in the resources:

<UserControl.Resources>
    <v:DataTypeConverter x:Key="DataTypeConverter"></v:DataTypeConverter>
</UserControl.Resources>

Solution 2:

Why not just use a converter that takes an object and returns a string of the object type?

Binding="{Binding SelectedItem, Converter={StaticResource ObjectToTypeString}}"

and define the converter as:

public class ObjectToTypeStringConverter : IValueConverter
{
    public object Convert(
     object value, Type targetType,
     object parameter, System.Globalization.CultureInfo culture)
    {
        return value.GetType().Name;            
    }

    public object ConvertBack(
     object value, Type targetType,
     object parameter, System.Globalization.CultureInfo culture)
    {
        // I don't think you'll need this
        throw new Exception("Can't convert back");
    }
}

You'll need to declare the static resource somewhere in your xaml:

<Window.Resources>
    <convs:ObjectToTypeStringConverter x:Key="ObjectToTypeString" />
</Window.Resources>

Where 'convs' in this case is the namespace of where the converter is.

Hope this helps.