DataStateBehavior for Enum instead of bool? String?

Question

Is there an easy way in WPF to bind VisualStates to enum values? Kinda like DataStateBehavior, but for an Enum?

Answer 1

The best way is to just go ahead and implement a Behavior that does just that -

public class EnumStateBehavior : Behavior<FrameworkElement>
{
    public object EnumProperty
    {
        get { return (object)GetValue(EnumPropertyProperty); }
        set { SetValue(EnumPropertyProperty, value); }
    }

    // Using a DependencyProperty as the backing store for EnumProperty.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty EnumPropertyProperty =
        DependencyProperty.Register("EnumProperty", typeof(object), typeof(EnumStateBehavior), new UIPropertyMetadata(null, EnumPropertyChanged));

    static void EnumPropertyChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        if (e.NewValue == null) return;

        EnumStateBehavior eb = sender as EnumStateBehavior;

        VisualStateManager.GoToElementState(eb.AssociatedObject, e.NewValue.ToString(), true);
    }

}

The usage is extremely simple - use as follows:

<i:Interaction.Behaviors>
        <local:EnumStateBehavior EnumProperty="{Binding MyEnumProperty}" />
</i:Interaction.Behaviors>

Answer 2

You can do it in pure xaml by using a DataTrigger per possible enum value with each trigger calling GoToStateAction with a different state. See the example below. For more details take a look at Enum driving a Visual State change via the ViewModel.

    <i:Interaction.Triggers>
        <ei:DataTrigger Binding="{Binding ConfirmedAnswerStatus}" Value="Unanswered">
            <ei:GoToStateAction StateName="UnansweredState" UseTransitions="False" />
        </ei:DataTrigger>
        <ei:DataTrigger Binding="{Binding ConfirmedAnswerStatus}" Value="Correct">
            <ei:GoToStateAction StateName="CorrectlyAnsweredState" UseTransitions="True" />
        </ei:DataTrigger>
        <ei:DataTrigger Binding="{Binding ConfirmedAnswerStatus}" Value="Incorrect">
            <ei:GoToStateAction StateName="IncorrectlyAnsweredState" UseTransitions="True" />
        </ei:DataTrigger>
    </i:Interaction.Triggers>