JosefNemec_Playnite/source/Playnite.DesktopApp/Controls/ComboBoxListBase.cs

using Playnite.Common;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Xml.Linq;

namespace Playnite.DesktopApp.Controls
{
    [TemplatePart(Name = "PART_ItemsPanel", Type = typeof(ItemsControl))]
    [TemplatePart(Name = "PART_ButtonClearFilter", Type = typeof(Button))]
    [TemplatePart(Name = "PART_TextFilterString", Type = typeof(TextBlock))]
    public abstract class ComboBoxListBase : Control
    {
        internal ItemsControl ItemsPanel;
        internal Button ButtonClearFilter;
        internal TextBlock TextFilterString;

        internal bool IgnoreChanges { get; set; }

        public bool IsThreeState
        {
            get => (bool)GetValue(IsThreeStateProperty);
            set => SetValue(IsThreeStateProperty, value);
        }

        public static readonly DependencyProperty IsThreeStateProperty = DependencyProperty.Register(
            nameof(IsThreeState),
            typeof(bool),
            typeof(ComboBoxListBase));

        public override void OnApplyTemplate()
        {
            base.OnApplyTemplate();

            ButtonClearFilter = Template.FindName("PART_ButtonClearFilter", this) as Button;
            TextFilterString = Template.FindName("PART_TextFilterString", this) as TextBlock;
            ItemsPanel = Template.FindName("PART_ItemsPanel", this) as ItemsControl;

            if (ButtonClearFilter != null)
            {
                ButtonClearFilter.Click += (_, e) => ClearButtonAction(e);
            }

            if (ItemsPanel != null)
            {
                BindingTools.SetBinding(
                    ItemsPanel,
                    ItemsControl.ItemsSourceProperty,
                    this,
                    "ItemsList");

                XNamespace pns = "http://schemas.microsoft.com/winfx/2006/xaml/presentation";

                ItemsPanel.ItemsPanel = Xaml.FromString<ItemsPanelTemplate>(new XDocument(
                    new XElement(pns + nameof(ItemsPanelTemplate),
                        new XElement(pns + nameof(VirtualizingStackPanel)))
                ).ToString());

                ItemsPanel.Template = Xaml.FromString<ControlTemplate>(new XDocument(
                     new XElement(pns + nameof(ControlTemplate),
                        new XElement(pns + nameof(ScrollViewer),
                            new XAttribute(nameof(ScrollViewer.Focusable), false),
                            new XElement(pns + nameof(ItemsPresenter))))
                ).ToString());

                ItemsPanel.ItemTemplate = Xaml.FromString<DataTemplate>(new XDocument(
                    new XElement(pns + nameof(DataTemplate),
                        new XElement(pns + nameof(CheckBox),
                            new XAttribute(nameof(CheckBox.IsChecked), "{Binding Selected}"),
                            new XAttribute(nameof(CheckBox.Content), "{Binding Item}"),
                            new XAttribute(nameof(CheckBox.Style), $"{{DynamicResource ComboBoxListItemStyle}}")))
                ).ToString());

                ScrollViewer.SetCanContentScroll(ItemsPanel, true);
                KeyboardNavigation.SetDirectionalNavigation(ItemsPanel, KeyboardNavigationMode.Contained);
                VirtualizingPanel.SetIsVirtualizing(ItemsPanel, true);
                VirtualizingPanel.SetVirtualizationMode(ItemsPanel, VirtualizationMode.Recycling);
            }
        }

        public virtual void ClearButtonAction(RoutedEventArgs e)
        {
        }
    }
}