优化更新代码，添加界面功能并整合

WPFluent/Layout/StackPanel.cs

@@ -0,0 +1,128 @@
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Markup;
+
+namespace WPFluent.Layout;
+
+[ContentProperty(nameof(Children))]
+public class StackPanel : Panel
+{
+    public static readonly DependencyProperty OrientationProperty =
+        DependencyProperty.Register(nameof(Orientation), typeof(Orientation), typeof(StackPanel), new FrameworkPropertyMetadata(Orientation.Vertical, FrameworkPropertyMetadataOptions.AffectsMeasure));
+
+    public Orientation Orientation
+    {
+        get => (Orientation)GetValue(OrientationProperty);
+        set => SetValue(OrientationProperty, value);
+    }
+
+    public static readonly DependencyProperty SpacingProperty =
+        DependencyProperty.Register(nameof(Spacing), typeof(double), typeof(StackPanel), new FrameworkPropertyMetadata(0.0, FrameworkPropertyMetadataOptions.AffectsMeasure));
+
+    public double Spacing
+    {
+        get => (double)GetValue(SpacingProperty);
+        set => SetValue(SpacingProperty, value);
+    }
+
+    protected override Size MeasureOverride(Size availableSize)
+    {
+        var spacing = Spacing;
+        var panelDesiredSize = new Size();
+
+        if (Orientation == Orientation.Vertical)
+        {
+            availableSize.Height = double.PositiveInfinity;
+            foreach (UIElement child in InternalChildren)
+            {
+                child.Measure(availableSize);
+                var childDesiredSize = child.DesiredSize;
+
+                panelDesiredSize.Height += childDesiredSize.Height;
+
+                if (child.Visibility != Visibility.Collapsed)
+                {
+                    panelDesiredSize.Height += spacing;
+                }
+
+                if (childDesiredSize.Width > panelDesiredSize.Width)
+                {
+                    panelDesiredSize.Width = childDesiredSize.Width;
+                }
+            }
+
+            if (InternalChildren.Count != 0)
+            {
+                panelDesiredSize.Height -= spacing;
+            }
+        }
+        else
+        {
+            availableSize.Width = double.PositiveInfinity;
+            foreach (UIElement child in InternalChildren)
+            {
+                child.Measure(availableSize);
+                var childDesiredSize = child.DesiredSize;
+
+                panelDesiredSize.Width += childDesiredSize.Width;
+
+                if (child.Visibility != Visibility.Collapsed)
+                {
+                    panelDesiredSize.Width += spacing;
+                }
+
+                if (childDesiredSize.Height > panelDesiredSize.Height)
+                {
+                    panelDesiredSize.Height = childDesiredSize.Height;
+                }
+            }
+
+            if (InternalChildren.Count != 0)
+            {
+                panelDesiredSize.Width -= spacing;
+            }
+        }
+
+        return panelDesiredSize;
+    }
+
+    protected override Size ArrangeOverride(Size finalSize)
+    {
+        var offset = 0d;
+        var spacing = Spacing;
+
+        if (Orientation == Orientation.Vertical)
+        {
+            foreach (UIElement child in InternalChildren)
+            {
+                var childDesiredSize = child.DesiredSize;
+
+                child.Arrange(new Rect(0, offset, finalSize.Width, childDesiredSize.Height));
+
+                offset += childDesiredSize.Height;
+
+                if (child.Visibility != Visibility.Collapsed)
+                {
+                    offset += spacing;
+                }
+            }
+        }
+        else
+        {
+            foreach (UIElement child in InternalChildren)
+            {
+                var childDesiredSize = child.DesiredSize;
+
+                child.Arrange(new Rect(offset, 0, childDesiredSize.Width, finalSize.Height));
+
+                offset += childDesiredSize.Width;
+                if (child.Visibility != Visibility.Collapsed)
+                {
+                    offset += spacing;
+                }
+            }
+        }
+
+        return finalSize;
+    }
+}