Separate version

Net40/HandyControl_Net40/Expression/Drawing/CommonExtensions.cs

@@ -0,0 +1,115 @@
+using System;
+using System.Collections.Generic;
+using System.Windows;
+
+namespace HandyControl.Expression.Drawing
+{
+    internal static class CommonExtensions
+    {
+        public static void AddRange<T>(this ICollection<T> collection, IEnumerable<T> newItems)
+        {
+            if (collection == null)
+            {
+                throw new ArgumentNullException(nameof(collection));
+            }
+
+            if (collection is List<T> list)
+            {
+                list.AddRange(newItems);
+            }
+            else
+            {
+                foreach (var local in newItems)
+                {
+                    collection.Add(local);
+                }
+            }
+        }
+
+        public static bool SetIfDifferent(this DependencyObject dependencyObject, DependencyProperty dependencyProperty, object value)
+        {
+            if (!Equals(dependencyObject.GetValue(dependencyProperty), value))
+            {
+                dependencyObject.SetValue(dependencyProperty, value);
+                return true;
+            }
+            return false;
+        }
+
+        public static bool EnsureListCount<T>(this IList<T> list, int count, Func<T> factory = null)
+        {
+            if (list == null)
+            {
+                throw new ArgumentNullException(nameof(list));
+            }
+            if (count < 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(count));
+            }
+            if (!list.EnsureListCountAtLeast(count, factory))
+            {
+                if (list.Count <= count)
+                {
+                    return false;
+                }
+
+                if (list is List<T> list2)
+                {
+                    list2.RemoveRange(count, list.Count - count);
+                }
+                else
+                {
+                    for (int i = list.Count - 1; i >= count; i--)
+                    {
+                        list.RemoveAt(i);
+                    }
+                }
+            }
+            return true;
+        }
+
+        public static bool EnsureListCountAtLeast<T>(this IList<T> list, int count, Func<T> factory = null)
+        {
+            if (list == null)
+            {
+                throw new ArgumentNullException(nameof(list));
+            }
+            if (count < 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(count));
+            }
+            if (list.Count >= count)
+            {
+                return false;
+            }
+
+            if ((list is List<T> list2) && (factory == null))
+            {
+                list2.AddRange(new T[count - list.Count]);
+            }
+            else
+            {
+                for (int i = list.Count; i < count; i++)
+                {
+                    list.Add((factory == null) ? default(T) : factory());
+                }
+            }
+            return true;
+        }
+
+        public static bool ClearIfSet(this DependencyObject dependencyObject, DependencyProperty dependencyProperty)
+        {
+            if (dependencyObject.ReadLocalValue(dependencyProperty) != DependencyProperty.UnsetValue)
+            {
+                dependencyObject.ClearValue(dependencyProperty);
+                return true;
+            }
+            return false;
+        }
+
+        public static void RemoveLast<T>(this IList<T> list)
+        {
+            list.RemoveAt(list.Count - 1);
+        }
+    }
+}