OnlineMonitorSystem/HandyControl/HandyControl_Shared/Controls/Other/BlendEffectBox.cs

using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Markup;
using System.Windows.Media.Effects;

namespace HandyControl.Controls;

[DefaultProperty("Content")]
[ContentProperty("Content")]
public class BlendEffectBox : Control
{
    private readonly ContentPresenter _effectBottomPresenter;

    private readonly ContentPresenter _effectTopPresenter;

    private bool _isInternalAction;

    public BlendEffectBox()
    {
        _effectTopPresenter = new ContentPresenter();
        ActualContent = _effectTopPresenter;

        _effectBottomPresenter = new ContentPresenter();
        _effectBottomPresenter.SetBinding(ContentPresenter.ContentProperty, new Binding(ContentProperty.Name)
        {
            Source = this
        });

        var effects = new ObservableCollection<Effect>();
        effects.CollectionChanged += OnEffectsChanged;
        Effects = effects;
    }

    private void OnEffectsChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        if (Effects == null || Effects.Count == 0)
        {
            ClearEffect(_effectTopPresenter);
            return;
        }

        if (_isInternalAction) return;

        _isInternalAction = true;
        AddEffect(_effectTopPresenter, Effects.Count);
        _isInternalAction = false;
    }

    private void ClearEffect(ContentPresenter presenter)
    {
        if (presenter == null) return;

        if (ReferenceEquals(_effectBottomPresenter, presenter))
        {
            _effectBottomPresenter.SetCurrentValue(EffectProperty, null);
            return;
        }

        presenter.SetCurrentValue(EffectProperty, null);
        ClearEffect(presenter.Content as ContentPresenter);
    }

    private void AddEffect(ContentPresenter presenter, int count)
    {
        var newCount = --count;

        if (newCount >= 0)
        {
            presenter.Effect = Effects[newCount];

            var nextCount = --count;
            if (nextCount >= 1)
            {
                var content = new ContentPresenter();
                presenter.Content = content;
                AddEffect(content, newCount);
            }
            else if (nextCount >= 0)
            {
                _effectBottomPresenter.Effect = Effects[0];
                presenter.Content = _effectBottomPresenter;
            }
            else
            {
                presenter.Content = _effectBottomPresenter;
            }
        }
    }

    [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
    [Bindable(true)]
    public Collection<Effect> Effects { get; }

    public static readonly DependencyProperty ContentProperty = DependencyProperty.Register(
        nameof(Content), typeof(FrameworkElement), typeof(BlendEffectBox), new PropertyMetadata(default(FrameworkElement)));

    public FrameworkElement Content
    {
        get => (FrameworkElement) GetValue(ContentProperty);
        set => SetValue(ContentProperty, value);
    }

    internal static readonly DependencyProperty ActualContentProperty = DependencyProperty.Register(
        nameof(ActualContent), typeof(FrameworkElement), typeof(BlendEffectBox), new PropertyMetadata(default(FrameworkElement)));

    internal FrameworkElement ActualContent
    {
        get => (FrameworkElement) GetValue(ActualContentProperty);
        set => SetValue(ActualContentProperty, value);
    }
}