improved performance of 'ControlCollection.Clear' and 'TreeNodeCollection.AddRange' methods;

Author: Meragon

System/Windows/Forms/Control.cs

@@ -1179,8 +1179,14 @@ public virtual void AddRange(Control[] controls)
             }
             public virtual void Clear()
             {
-                while (Count != 0)
-                    RemoveAt(Count - 1);
+                var tItems = new List<Control>(items);
+                
+                items.Clear();
+            
+                owner.PerformLayout();
+                
+                for (int i = 0; i < tItems.Count; i++)
+                    owner.OnControlRemoved(new ControlEventArgs(tItems[i]));
             }
             public bool Contains(Control control)
             {

System/Windows/Forms/TreeNode.cs

@@ -20,10 +20,14 @@ public class TreeNode
         private string text;
         private bool visible = true;
 
+        public TreeNode() : this(string.Empty, null)
+        { }
+        
         public TreeNode(string text) : this(text, null)
         {
             this.text = text;
         }
+        
         public TreeNode(string text, TreeNode[] children)
         {
             ImageColor = Color.White;

System/Windows/Forms/TreeNodeCollection.cs

@@ -74,7 +74,20 @@ public virtual TreeNode this[string key]
 
         public virtual int Add(TreeNode node)
         {
-            return AddInternal(node, 0);
+            if (node == null)
+                throw new ArgumentNullException("node");
+
+            if (node.parent != null) node.Remove();
+
+            node.parent = owner;
+            node.index = items.Count;
+
+            items.Add(node);
+
+            if (owner.TreeView != null) 
+                node.treeView = owner.TreeView;
+
+            return node.index;
         }
         public virtual TreeNode Add(string text)
         {
@@ -98,8 +111,20 @@ public virtual void AddRange(TreeNode[] nodes)
 
             for (int i = 0; i < nodes.Length; i++)
             {
-                AddInternal(nodes[i], i);
+                var node = nodes[i];
+                if (node == null)
+                    throw new InvalidOperationException("node is null");
+
+                if (node.parent != null) node.Remove();
+
+                node.parent = owner;
+                node.index = items.Count + i;
+
+                if (owner.TreeView != null) 
+                    node.treeView = owner.TreeView;
             }
+            
+            items.AddRange(nodes);
         }
         public virtual void Clear()
         {
@@ -271,25 +296,6 @@ private static ArrayList FindInternal(string key, bool searchAllChildren, TreeNo
                 }
             return nodes;
         }
-        private int AddInternal(TreeNode node, int delta)
-        {
-            if (node == null)
-                throw new ArgumentNullException("node");
-
-            if (node.parent != null) node.Remove();
-
-            node.parent = owner;
-            node.index = items.Count;
-
-            items.Add(node);
-
-            if (owner.TreeView != null)
-            {
-                node.treeView = owner.TreeView;
-            }
-
-            return node.index;
-        }
         private bool IsValidIndex(int index)
         {
             return index >= 0 && index < Count;