1:Use BreadcrumbConstants.cs

2:Optimize MeasureOverride && ArrangeOverride

src/AtomUI.Controls/Breadcrumb/BreadcrumbStackPanel.cs

@@ -7,30 +7,15 @@ internal class BreadcrumbStackPanel : Panel
 {
     protected override Size MeasureOverride(Size availableSize)
     {
-        return MeasureOverrideNoExpanding(availableSize);
-    }
-
-    private Size MeasureOverrideNoExpanding(Size availableSize)
-    {
-        var layoutSlotSize = availableSize;
-        layoutSlotSize = layoutSlotSize.WithWidth(double.PositiveInfinity);
-        var hasVisibleChild = false;
-        var targetWidth     = 0d;
-        var targetHeight    = 0d;
+        var  targetHeight = 0d;
+        var  targetWidth  = 0d;
         foreach (var child in Children)
         {
             if (child is BreadcrumbItem box)
             {
-                var isVisible = box.IsVisible;
-                if (isVisible && !hasVisibleChild)
-                {
-                    hasVisibleChild = true;
-                }
-
-                box.Measure(layoutSlotSize);
-                var childDesiredSize = box.DesiredSize;
-                targetWidth  += childDesiredSize.Width;
-                targetHeight =  Math.Max(targetHeight, childDesiredSize.Height);
+                box.Measure(availableSize);
+                targetWidth  += box.DesiredSize.Width;
+                targetHeight =  Math.Max(targetHeight, box.DesiredSize.Height);
             }
         }
 
@@ -38,12 +23,6 @@ internal class BreadcrumbStackPanel : Panel
     }
     
     protected override Size ArrangeOverride(Size finalSize)
-    {
-        ArrangeOverrideNoExpanding(finalSize);
-        return finalSize;
-    }
-
-    private Size ArrangeOverrideNoExpanding(Size finalSize)
     {
         var previousChildSize = 0.0;
         var offsetX           = 0d;
@@ -52,19 +31,11 @@ internal class BreadcrumbStackPanel : Panel
         {
             if (child is BreadcrumbItem box)
             {
-                if (!box.IsVisible)
-                {
-                    continue;
-                }
-
                 previousChildSize = box.DesiredSize.Width;
-
                 box.Arrange(new Rect(new Point(offsetX, offsetY), box.DesiredSize));
                 offsetX += previousChildSize;
             }
         }
-
         return finalSize;
     }
-
 }

src/AtomUI.Controls/Breadcrumb/Themes/BreadcrumbConstants.cs

@@ -2,5 +2,6 @@
 
 internal static class BreadcrumbConstants
 {
-    public const string TextPresenterPart = "RootLayout";
+    public const string FramePart = "PART_Frame";
+    public const string TextPresenterPart = "PART_ItemsPresenter";
 }

src/AtomUI.Controls/Breadcrumb/Themes/BreadcrumbItemTheme.axaml

@@ -4,10 +4,6 @@
     xmlns:atom="https://atomui.net">
     <atom:BoolToThicknessConverter x:Key="BoolToThicknessConverter" />
     <atom:StringToTextBlockConverter x:Key="StringToTextBlockConverter" VerticalAlignment="Center" />
-    <!--
-       x:key表示，如果遇到atom:Breadcrumb，那就是我
-       TargetType="atom:Breadcrumb"表示本axaml中的所有属性均来自于atom:Breadcrumb class
-    -->
     <ControlTheme x:Key="{x:Type atom:BreadcrumbItem}" TargetType="atom:BreadcrumbItem">
         <Setter Property="Template">
             <ControlTemplate>

src/AtomUI.Controls/Breadcrumb/Themes/BreadcrumbTheme.axaml

@@ -3,28 +3,20 @@
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
     xmlns:atom="https://atomui.net">
     <atom:BoolToThicknessConverter x:Key="BoolToThicknessConverter" />
-    <!--
-       x:key表示，如果遇到atom:Breadcrumb，那就是我
-       TargetType="atom:Breadcrumb"表示本axaml中的所有属性均来自于atom:Breadcrumb class
-    -->
     <ControlTheme x:Key="{x:Type atom:Breadcrumb}" TargetType="atom:Breadcrumb">
-        <!--
-        把外部 ViewModel 里的集合 Breadcrumbs 绑进来。（在 Theme 里写死绑定是一种偷懒写法；实际可以删掉，让外部自己绑。）
-        <Setter Property="ItemsSource" Value="{TemplateBinding ItemsSource}" />，直接写在下面就会报错
-        -->
         <Setter Property="HorizontalAlignment" Value="Left" />
         <Setter Property="VerticalAlignment" Value="Center" />
         <Setter Property="Foreground" Value="{DynamicResource {x:Static atom:BreadcrumbTokenKey.ItemColor}}" />
         <Setter Property="IconSize" Value="{DynamicResource {x:Static atom:BreadcrumbTokenKey.IconSize}}" />
         <Setter Property="Template">
             <ControlTemplate>
-                <Border Name="FramePart"
+                <Border Name="{x:Static atom:BreadcrumbConstants.FramePart}"
                         CornerRadius="{TemplateBinding CornerRadius}"
                         Padding="{TemplateBinding Padding}"
                         ClipToBounds="True"
                         VerticalAlignment="Center"
                         HorizontalAlignment="Center">
-                    <ItemsPresenter Name="PART_ItemsPresenter">
+                    <ItemsPresenter Name="{x:Static atom:BreadcrumbConstants.TextPresenterPart}">
                         <ItemsPresenter.ItemsPanel>
                             <ItemsPanelTemplate>
                                 <atom:BreadcrumbStackPanel />