优化更新代码，添加界面功能并整合

WPFluent/Controls/GridView/GridViewHeaderRowPresenter.cs

@@ -0,0 +1,83 @@
+
+
+
+using System.Diagnostics;
+using System.Reflection;
+using System.Windows.Controls;
+
+namespace WPFluent.Controls;
+
+/// <summary>
+/// Extends <see cref="System.Windows.Controls.GridViewHeaderRowPresenter"/>, and adds layout support for <see
+/// cref="GridViewColumn"/>, which can have <see cref="GridViewColumn.MinWidth"/> and <see
+/// cref="GridViewColumn.MaxWidth"/>.
+/// </summary>
+public class GridViewHeaderRowPresenter : System.Windows.Controls.GridViewHeaderRowPresenter
+{
+    public GridViewHeaderRowPresenter() { Loaded += OnLoaded; }
+
+    private void OnLoaded(object sender, RoutedEventArgs e) { UpdateIndicatorStyle(); }
+
+    private void UpdateIndicatorStyle()
+    {
+        FieldInfo? indicatorField = typeof(System.Windows.Controls.GridViewHeaderRowPresenter).GetField(
+            "_indicator",
+            BindingFlags.NonPublic | BindingFlags.Instance);
+
+        if (indicatorField == null)
+        {
+            Debug.WriteLine("Failed to get the _indicator field");
+            return;
+        }
+
+        if (indicatorField.GetValue(this) is Separator indicator)
+        {
+            indicator.Margin = new Thickness(0);
+            indicator.Width = 3.0;
+
+            ResourceDictionary resourceDictionary = new()
+            {
+                Source =
+                    new Uri(
+                        "pack://application:,,,/WPFluent;component/Controls/GridView/GridViewHeaderRowIndicator.xaml",
+                        UriKind.Absolute),
+            };
+
+            if (resourceDictionary["GridViewHeaderRowIndicatorTemplate"] is ControlTemplate template)
+            {
+                indicator.Template = template;
+            }
+            else
+            {
+                Debug.WriteLine("Failed to get the GridViewHeaderRowIndicatorTemplate");
+            }
+        }
+    }
+
+    protected override Size ArrangeOverride(Size arrangeSize)
+    {
+        // update the desired width of each column (clamps desiredwidth to MinWidth and MaxWidth)
+        if (Columns != null)
+        {
+            foreach (GridViewColumn column in Columns.OfType<GridViewColumn>())
+            {
+                column.UpdateDesiredWidth();
+            }
+        }
+
+        return base.ArrangeOverride(arrangeSize);
+    }
+
+    protected override Size MeasureOverride(Size constraint)
+    {
+        if (Columns != null)
+        {
+            foreach (GridViewColumn column in Columns.OfType<GridViewColumn>())
+            {
+                column.UpdateDesiredWidth();
+            }
+        }
+
+        return base.MeasureOverride(constraint);
+    }
+}