WIP Adding MultiSelectionComboBox

samples/Avalonia.Labs.Catalog/ViewModels/MultiSelectionComboBoxViewModel.cs

@@ -0,0 +1,17 @@
+using System.Collections.Generic;
+using Avalonia.Labs.Catalog.Views;
+
+namespace Avalonia.Labs.Catalog.ViewModels;
+
+public class MultiSelectionComboBoxViewModel : ViewModelBase
+{
+    static MultiSelectionComboBoxViewModel()
+    {
+        ViewLocator.Register(typeof(MultiSelectionComboBoxViewModel), () => new MultiSelectionComboBoxView());
+    }
+
+    public List<string> Items { get; } =
+    [
+        "Hello", "Avalonia"
+    ];
+}

samples/Avalonia.Labs.Catalog/Views/MultiSelectionComboBoxView.axaml

@@ -0,0 +1,17 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:controls="clr-namespace:Avalonia.Labs.Controls;assembly=Avalonia.Labs.Controls"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             x:Class="Avalonia.Labs.Catalog.Views.MultiSelectionComboBoxView">
+  <Grid ColumnDefinitions="*,3,*">
+    <ScrollViewer>
+      <ItemsControl x:Name="Properties">
+      </ItemsControl>
+    </ScrollViewer>
+
+    <controls:MultiSelectionComboBox Grid.Column="2" x:Name="MultiSelectionComboBox" 
+                                     ItemsSource="{Binding Items}"/>
+  </Grid>
+</UserControl>

samples/Avalonia.Labs.Catalog/Views/MultiSelectionComboBoxView.axaml.cs

@@ -0,0 +1,48 @@
+using System.Collections.Generic;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Templates;
+using Avalonia.Data;
+using Avalonia.Interactivity;
+using Avalonia.Labs.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace Avalonia.Labs.Catalog.Views;
+
+public partial class MultiSelectionComboBoxView : UserControl
+{
+    public MultiSelectionComboBoxView()
+    {
+        InitializeComponent();
+    }
+
+    protected override void OnLoaded(RoutedEventArgs e)
+    {
+        base.OnLoaded(e);
+
+        var mscb = this.Find<MultiSelectionComboBox>("MultiSelectionComboBox")!;
+        var properties = this.Find<ItemsControl>("Properties");
+
+        properties!.ItemsSource = new List<AvaloniaProperty>()
+        {
+            MultiSelectionComboBox.IsReadOnlyProperty,
+            MultiSelectionComboBox.IsEditableProperty
+        };
+
+        properties.ItemTemplate = new FuncDataTemplate<AvaloniaProperty>(
+            property => true,
+            property =>
+        {
+
+            if (property.PropertyType == typeof(bool))
+            {
+                var checkBox = new CheckBox() {Content = property.Name};
+                mscb.Bind(property, new Binding(nameof(checkBox.IsChecked), BindingMode.TwoWay));
+                return checkBox;
+            }
+
+            return new TextBox(){Text = "Unknown DataType"};
+        });
+    }
+}

samples/Avalonia.Labs.Catalog/Views/WelcomeView.axaml

@@ -3,6 +3,7 @@
              xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              xmlns:viewModels="clr-namespace:Avalonia.Labs.Catalog.ViewModels"
+             xmlns:controls="clr-namespace:Avalonia.Labs.Controls;assembly=Avalonia.Labs.Controls"
              mc:Ignorable="d"
              d:DesignWidth="800"
              d:DesignHeight="450"
@@ -173,6 +174,17 @@
         <Label FontSize="18"
                VerticalAlignment="Center">Tab Layout</Label>
       </Button>
+      <Button HorizontalAlignment="Stretch"
+              Height="60"
+              Command="{Binding NavigateTo}"
+              CornerRadius="10"
+              Margin="0,5">
+        <Button.CommandParameter>
+          <viewModels:MultiSelectionComboBoxViewModel/>
+        </Button.CommandParameter>
+        <Label FontSize="18"
+               VerticalAlignment="Center">MultiSelectionComboBox</Label>
+      </Button>
     </StackPanel>
   </Grid>
 </ScrollViewer>

src/Avalonia.Labs.Controls/MultiSelectionComboBox/AddedItemEventArgs.cs

@@ -0,0 +1,43 @@
+using System.Collections;
+using Avalonia.Interactivity;
+
+namespace Avalonia.Labs.Controls
+{
+    /// <summary>
+    /// Provides data for the <see cref="MultiSelectionComboBox.AddedItemEvent"/>
+    /// </summary>
+    public class AddedItemEventArgs : RoutedEventArgs
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AddedItemEventArgs"/> class.
+        /// </summary>
+        /// <param name="routedEvent">The AddedItemEvent</param>
+        /// <param name="source">The source object</param>
+        /// <param name="addedItem">The added object</param>
+        /// <param name="targetList">The target <see cref="IList"/> where the <see cref="AddedItem"/> should be added</param>
+        public AddedItemEventArgs(RoutedEvent routedEvent,
+                                  object source,
+                                  object? addedItem,
+                                  IList? targetList)
+            : base(routedEvent, source)
+        {
+            this.AddedItem = addedItem;
+            this.TargetList = targetList;
+        }
+
+        /// <summary>
+        /// Gets the added item
+        /// </summary>
+        public object? AddedItem { get; }
+
+        /// <summary>
+        /// Gets the <see cref="IList"/> where the <see cref="AddedItem"/> was added to
+        /// </summary>
+        public IList? TargetList { get; }
+    }
+
+    /// <summary>
+    /// RoutedEventHandler used for the <see cref="MultiSelectionComboBox.AddedItemEvent"/>.
+    /// </summary>
+    public delegate void AddedItemEventArgsHandler(object? sender, AddedItemEventArgs args);
+}

src/Avalonia.Labs.Controls/MultiSelectionComboBox/AddingItemEventArgs.cs

@@ -0,0 +1,93 @@
+using System;
+using System.Collections;
+using System.Globalization;
+using Avalonia.Interactivity;
+
+namespace Avalonia.Labs.Controls
+{
+    /// <summary>
+    /// Provides data for the <see cref="MultiSelectionComboBox.AddingItemEvent"/>
+    /// </summary>
+    public class AddingItemEventArgs : RoutedEventArgs
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AddingItemEventArgs"/> class.
+        /// </summary>
+        /// <param name="routedEvent">The AddingItemEvent</param>
+        /// <param name="source">The source object</param>
+        /// <param name="input">The input string to parse</param>
+        /// <param name="parsedObject">The parsed object</param>
+        /// <param name="accepted"><see langword="true"/> if the <see cref="ParsedObject"/> is accepted otherwise <see langword="false"/></param>
+        /// <param name="targetList">The target <see cref="IList"/> where the <see cref="ParsedObject"/> should be added</param>
+        /// <param name="targetType">the target <see cref="Type"/> to which the <see cref="Input"/> should be converted to</param>
+        /// <param name="stringFormat">the string format which can be used to control the <see cref="Parser"/></param>
+        /// <param name="culture">the culture which can be used to control the <see cref="Parser"/></param>
+        /// <param name="parser">The used parser</param>
+        public AddingItemEventArgs(RoutedEvent routedEvent,
+                                   object source,
+                                   string? input,
+                                   object? parsedObject,
+                                   bool accepted,
+                                   IList? targetList,
+                                   Type? targetType,
+                                   string? stringFormat,
+                                   CultureInfo culture,
+                                   IParseStringToObject? parser)
+            : base(routedEvent, source)
+        {
+            this.Input = input;
+            this.ParsedObject = parsedObject;
+            this.Accepted = accepted;
+            this.TargetList = targetList;
+            this.TargetType = targetType;
+            this.StringFormat = stringFormat;
+            this.Culture = culture;
+            this.Parser = parser;
+        }
+
+        /// <summary>
+        /// The text input to parse 
+        /// </summary>
+        public string? Input { get; }
+
+        /// <summary>
+        /// Gets or sets the parsed object to add. You can override it
+        /// </summary>
+        public object? ParsedObject { get; set; }
+
+        /// <summary>
+        /// Gets the string format which can be used to control the <see cref="Parser"/>
+        /// </summary>
+        public string? StringFormat { get; }
+
+        /// <summary>
+        /// Gets the culture which can be used to control the <see cref="Parser"/>
+        /// </summary>
+        public CultureInfo Culture { get; }
+
+        /// <summary>
+        /// Gets the <see cref="IParseStringToObject"/>-Instance which was used to parse the <see cref="Input"/> to the <see cref="ParsedObject"/>
+        /// </summary>
+        public IParseStringToObject? Parser { get; }
+
+        /// <summary>
+        /// Gets the target <see cref="Type"/> to which the <see cref="Input"/> should be converted to
+        /// </summary>
+        public Type? TargetType { get; }
+
+        /// <summary>
+        /// Gets the <see cref="IList"/> where the <see cref="ParsedObject"/> should be added
+        /// </summary>
+        public IList? TargetList { get; }
+
+        /// <summary>
+        /// Gets or sets whether the <see cref="ParsedObject"/> is accepted and can be added
+        /// </summary>
+        public bool Accepted { get; set; }
+    }
+
+    /// <summary>
+    /// RoutedEventHandler used for the <see cref="MultiSelectionComboBox.AddingItemEvent"/>.
+    /// </summary>
+    public delegate void AddingItemEventArgsHandler(object? sender, AddingItemEventArgs args);
+}

src/Avalonia.Labs.Controls/MultiSelectionComboBox/DefaultStringToObjectParser.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Collections;
+using System.ComponentModel;
+using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
+using System.Linq;
+
+namespace Avalonia.Labs.Controls
+{
+    /// <summary>
+    ///   This class is a helper class for the <see cref="MultiSelectionComboBox"/>. 
+    ///   It uses the <see cref="TypeConverter"/> for the elements <see cref="Type"/>. If you need more control
+    ///   over the conversion you should create your own class which implements <see cref="IParseStringToObject"/>
+    /// </summary>
+    #if NET6_0_OR_GREATER
+    [RequiresUnreferencedCode("Hello World")]
+    #endif
+    public class DefaultStringToObjectParser : IParseStringToObject
+    {
+        public static readonly DefaultStringToObjectParser Instance = new();
+
+        /// <inheritdoc />
+        public bool TryCreateObjectFromString(string? input,
+                                              out object? result,
+                                              CultureInfo? culture = null,
+                                              string? stringFormat = null,
+                                              Type? targetType = null)
+        {
+            try
+            {
+                // If the input is null the result is also null
+                if (input is null)
+                {
+                    result = null;
+                    return true;
+                }
+
+                // If we don't know the target type we cannot convert in this class.
+                // Either provide the target type or roll your own class implementing IParseStringToObject
+                if (targetType is null)
+                {
+                    result = null;
+                    return false;
+                }
+
+                result = TypeDescriptor.GetConverter(targetType).ConvertFromString(default!, culture ?? CultureInfo.InvariantCulture, input);
+                return true;
+            }
+            catch
+            {
+                result = null;
+                return false;
+            }
+        }
+
+        /// <summary>
+        /// Tries to get the elements <see cref="Type"/> for a given <see cref="IEnumerable"/>
+        /// </summary>
+        /// <param name="list">Any collection of elements</param>
+        /// <returns>the elements <see cref="Type"/></returns>
+        public Type? GetElementType(IEnumerable? list)
+        {
+            if (list is null)
+            {
+                return null;
+            }
+
+            var listType = list.GetType();
+
+            return listType.IsGenericType ? listType.GetGenericArguments().FirstOrDefault() : listType.GetElementType();
+        }
+    }
+}

src/Avalonia.Labs.Controls/MultiSelectionComboBox/ICompareObjectToString.cs

@@ -0,0 +1,55 @@
+using System;
+
+namespace Avalonia.Labs.Controls
+{
+    /// <summary>
+    ///  Defines a function that is used to check if a given string represents a given object of any type.
+    /// </summary>
+    public interface ICompareObjectToString
+    {
+        /// <summary>
+        /// Checks if the given input string matches to the given object
+        /// </summary>
+        /// <param name="input">The string to compare</param>
+        /// <param name="objectToCompare">The object to compare</param>
+        /// <param name="stringComparison">The <see cref="StringComparison"/> used to check if the string matches</param>
+        /// <param name="stringFormat">The string format to apply</param>
+        /// <returns>true if the string represents the object, otherwise false.</returns>
+        public bool CheckIfStringMatchesObject(string? input, object? objectToCompare, StringComparison stringComparison, string? stringFormat);
+    }
+
+    public class DefaultObjectToStringComparer : ICompareObjectToString
+    {
+        public static DefaultObjectToStringComparer Instance { get; } = new();
+
+        /// <inheritdoc/>
+        public bool CheckIfStringMatchesObject(string? input, object? objectToCompare, StringComparison stringComparison, string? stringFormat)
+        {
+            if (input is null)
+            {
+                return objectToCompare is null;
+            }
+
+            if (objectToCompare is null)
+            {
+                return false;
+            }
+
+            string? objectText;
+            if (string.IsNullOrEmpty(stringFormat))
+            {
+                objectText = objectToCompare.ToString();
+            }
+            else if (stringFormat.Contains("{") && stringFormat.Contains("}"))
+            {
+                objectText = string.Format(stringFormat, objectToCompare);
+            }
+            else
+            {
+                objectText = string.Format($"{{0:{stringFormat}}}", objectToCompare);
+            }
+
+            return input.Equals(objectText, stringComparison);
+        }
+    }
+}