feat: initialize breadcrumb.

src/Ursa/Controls/Breadcrumb/Breadcrumb.cs

@@ -0,0 +1,85 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Templates;
+using Avalonia.Data;
+using Avalonia.Layout;
+using Avalonia.Metadata;
+
+namespace Ursa.Controls;
+
+public class Breadcrumb: ItemsControl
+{
+    private static readonly ITemplate<Panel?> _defaultPanel =
+        new FuncTemplate<Panel?>(() => new StackPanel() { Orientation = Orientation.Horizontal });
+    
+    
+    public static readonly StyledProperty<IBinding?> IconBindingProperty = AvaloniaProperty.Register<Breadcrumb, IBinding?>(
+        nameof(IconBinding));
+
+    [AssignBinding]
+    [InheritDataTypeFromItems(nameof(ItemsSource))]
+    public IBinding? IconBinding
+    {
+        get => GetValue(IconBindingProperty);
+        set => SetValue(IconBindingProperty, value);
+    }
+
+    public static readonly StyledProperty<IBinding?> CommandBindingProperty = AvaloniaProperty.Register<Breadcrumb, IBinding?>(
+        nameof(CommandBinding));
+
+    [AssignBinding]
+    [InheritDataTypeFromItems(nameof(ItemsSource))]
+    public IBinding? CommandBinding
+    {
+        get => GetValue(CommandBindingProperty);
+        set => SetValue(CommandBindingProperty, value);
+    }
+
+    public static readonly StyledProperty<object?> SeparatorProperty = AvaloniaProperty.Register<Breadcrumb, object?>(
+        nameof(Separator));
+
+    /// <summary>
+    /// Separator between items.
+    /// Usage: Separator can only be raw string or ITemplate&lt;Control&gt;.
+    /// </summary>
+    public object? Separator
+    {
+        get => GetValue(SeparatorProperty);
+        set => SetValue(SeparatorProperty, value);
+    }
+    
+    static Breadcrumb()
+    {
+        ItemsPanelProperty.OverrideDefaultValue<Breadcrumb>(_defaultPanel);
+    }
+    
+    protected override bool NeedsContainerOverride(object? item, int index, out object? recycleKey)
+    {
+        return NeedsContainer<BreadcrumbItem>(item, out recycleKey);
+    }
+
+    protected override Control CreateContainerForItemOverride(object? item, int index, object? recycleKey)
+    {
+        return new BreadcrumbItem();
+    }
+
+    protected override void PrepareContainerForItemOverride(Control container, object? item, int index)
+    {
+        base.PrepareContainerForItemOverride(container, item, index);
+        if (container is BreadcrumbItem breadcrumbItem)
+        {
+            if (!breadcrumbItem.IsSet(BreadcrumbItem.SeparatorProperty))
+            {
+                SeparatorProperty.Changed.AddClassHandler<Breadcrumb, object?>((o, e) =>
+                {
+                    breadcrumbItem.Separator = e.NewValue.Value switch
+                    {
+                        string s => s,
+                        ITemplate<Control> t => t.Build(),
+                        _ => e.NewValue.Value?.ToString()
+                    };
+                });
+            }
+        }
+    }
+}

src/Ursa/Controls/Breadcrumb/BreadcrumbItem.cs

@@ -0,0 +1,41 @@
+using System.Windows.Input;
+using Avalonia;
+using Avalonia.Controls;
+
+namespace Ursa.Controls;
+
+public class BreadcrumbItem: ContentControl
+{
+    public static readonly StyledProperty<object?> SeparatorProperty =
+        AvaloniaProperty.Register<BreadcrumbItem, object?>(
+            nameof(Separator), "/");
+
+    public object? Separator
+    {
+        get => GetValue(SeparatorProperty);
+        set => SetValue(SeparatorProperty, value);
+    }
+
+    public static readonly StyledProperty<object?> IconProperty = AvaloniaProperty.Register<BreadcrumbItem, object?>(
+        nameof(Icon));
+
+    public object? Icon
+    {
+        get => GetValue(IconProperty);
+        set => SetValue(IconProperty, value);
+    }
+
+    public static readonly StyledProperty<ICommand?> CommandProperty = AvaloniaProperty.Register<BreadcrumbItem, ICommand?>(
+        nameof(Command));
+
+    public ICommand? Command
+    {
+        get => GetValue(CommandProperty);
+        set => SetValue(CommandProperty, value);
+    }
+
+    static BreadcrumbItem()
+    {
+        
+    }
+}