HandyControl/src/Shared/System.Windows.Interactivity/Interaction.cs

using System;
using System.Windows;

namespace HandyControl.Interactivity;

public static class Interaction
{
    private static readonly DependencyProperty TriggersProperty =
        DependencyProperty.RegisterAttached("ShadowTriggers", typeof(TriggerCollection), typeof(Interaction),
            new FrameworkPropertyMetadata(OnTriggersChanged));

    private static readonly DependencyProperty BehaviorsProperty =
        DependencyProperty.RegisterAttached("ShadowBehaviors", typeof(BehaviorCollection), typeof(Interaction),
            new FrameworkPropertyMetadata(OnBehaviorsChanged));

    internal static bool ShouldRunInDesignMode { get; set; }

    public static TriggerCollection GetTriggers(DependencyObject obj)
    {
        var triggerCollection = (TriggerCollection) obj.GetValue(TriggersProperty);
        if (triggerCollection == null)
        {
            triggerCollection = new TriggerCollection();
            obj.SetValue(TriggersProperty, triggerCollection);
        }
        return triggerCollection;
    }

    public static BehaviorCollection GetBehaviors(DependencyObject obj)
    {
        var behaviorCollection = (BehaviorCollection) obj.GetValue(BehaviorsProperty);
        if (behaviorCollection == null)
        {
            behaviorCollection = new BehaviorCollection();
            obj.SetValue(BehaviorsProperty, behaviorCollection);
        }
        return behaviorCollection;
    }

    private static void OnBehaviorsChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
    {
        var oldValue = (BehaviorCollection) args.OldValue;
        var newValue = (BehaviorCollection) args.NewValue;
        if (Equals(oldValue, newValue))
            return;
        if (oldValue?.AssociatedObject != null)
            oldValue.Detach();
        if (newValue == null || obj == null)
            return;
        if (newValue.AssociatedObject != null)
            throw new InvalidOperationException(ExceptionStringTable
                .CannotHostBehaviorCollectionMultipleTimesExceptionMessage);
        newValue.Attach(obj);
    }

    private static void OnTriggersChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args)
    {
        var oldValue = args.OldValue as TriggerCollection;
        var newValue = args.NewValue as TriggerCollection;
        if (Equals(oldValue, newValue))
            return;
        if (oldValue?.AssociatedObject != null)
            oldValue.Detach();
        if (newValue == null || obj == null)
            return;
        if (newValue.AssociatedObject != null)
            throw new InvalidOperationException(ExceptionStringTable
                .CannotHostTriggerCollectionMultipleTimesExceptionMessage);
        newValue.Attach(obj);
    }

    internal static bool IsElementLoaded(FrameworkElement element)
    {
        return element.IsLoaded;
    }
}