更新

WPFDark/Controls/Converters/IndentToMarginConverter.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Globalization;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Data;
+using Jewelry.Collections;
+
+using WPFDark.Internals;
+
+namespace WPFDark.Controls.Converters
+{
+    public class IndentToMarginConverter : IMultiValueConverter
+    {
+        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
+        {
+            var thickness = new Thickness(0);
+            if (values is null)
+                return thickness;
+
+            if (!(values[0] is TreeViewItem item))
+                return thickness;
+
+            var length = 19.0;
+
+            if (values.Length == 2)
+                if (values[1] is double v)
+                    length = v;
+
+            var k = length * item.GetDepth();
+
+            // ReSharper disable once CompareOfFloatsByEqualityOperator
+            if (k == 0)
+                return thickness;
+
+            if (_thicknessCache.TryGetValue(k, out var result) == false)
+            {
+                result = new Thickness(k, 0, 0, 0);
+
+                _thicknessCache.Add(k, result);
+            }
+
+            return result;
+        }
+
+        private static readonly LruCache<double, object> _thicknessCache = new LruCache<double, object>(8);
+
+        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}