更新

WPFDark/Controls/Converters/TreeListViewItemMarginConverter.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Globalization;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+
+using WPFDark.Internals;
+
+namespace WPFDark.Controls.Converters
+{
+    public class TreeListViewItemMarginConverter : IValueConverter
+    {
+        public double Length { get; set; }
+        public bool IsFirstColumn { get; set; }
+
+        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            if (!(value is TreeViewItem item))
+                return new Thickness(0);
+
+            var right = Length * (item.GetDepth() + 1.0);
+            var left = IsFirstColumn ? -6.0 : right * -1.0;
+
+            return new Thickness(left, 0, right, 0);
+        }
+
+        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}