在视图中使用自定义TreeView类

Question

我有一个定制的TreeView类，如下所示：

using System.Windows.Forms;
namespace My.Namespace
{
    public partial class SimpleTree : System.Windows.Forms.TreeView
    {
        private TreeNode topNode; ////////// 
        private TreeNode lowerNode1;
        private TreeNode lowerNode2;
        private TreeNode lowerNode3;

        public SimpleTree()
        {
            InitializeComponent();

            BuildTree();

            TreeViewEventArgs eventArgs = new TreeViewEventArgs(topNode, TreeViewAction.Unknown);

            this.ExpandAll(); // must be after adding the nodes

        }

        private void BuildTree()
        {
            this.Name = "Simple Tree";

            topNode = new TreeNode("Top Node");
            topNode.Name = "Top Node"
            this.Nodes.Add(topNode);

            lowerNode1 = new TreeNode("Lower Node 1");
            lowerNode1.Name = "Lower Node 1";
            topNode.Nodes.Add(lowerNode1);

            lowerNode2 = new TreeNode("Lower Node 2");
            lowerNode2.Name = "Lower Node 2";
            topNode.Nodes.Add(lowerNode2);

            lowerNode3 = new TreeNode("Lower Node 3");
            lowerNode3.Name = "Lower Node 3";
            topNode.Nodes.Add(lowerNode3);
        }
        // This is a simplified example, much more functionality here in real code
    }
}

我将这个SimpleTree包含在ProjectView.cs中(它有许多组件)。

在ProjectView.Designer.cs中，有以下内容：

private SimpleTreeView trvSimple;
this.trvSimple = new My.Namespace.SimpleTreeView();

this.trvSimple.BackColor = System.Drawing.Color.White;
this.trvSimple.Location = new System.Drawing.Point(3, 65);
this.trvSimple.Name = "trvSimple";
this.trvSimple.Scrollable = false;
this.trvSimple.Size = new System.Drawing.Size(128, 109);
this.trvSimple.TabIndex = 1;
this.trvSimple.Text = "trvSimple";
this.trvSimple.BeforeCollapse += new System.Windows.Forms.TreeViewCancelEventHandler(this.trvSimple_BeforeCollapse);
this.trvSimple.BeforeSelect += new System.Windows.Forms.TreeViewCancelEventHandler(this.trvSimple_BeforeSelect);

这一切都有效。这棵树看起来像：

顶节点 -低节点1 -低节点2 -低节点3

但是，当我在ProjectView中更改其他任何内容时，Visual随后将此代码添加到ProjectView.Designer.cs中

System.Windows.Forms.TreeNode treeNode1 = new System.Windows.Forms.TreeNode("Lower Node 1");
System.Windows.Forms.TreeNode treeNode2 = new System.Windows.Forms.TreeNode("Lower Node 2");
System.Windows.Forms.TreeNode treeNode3 = new System.Windows.Forms.TreeNode("Lower Node 3");
System.Windows.Forms.TreeNode treeNode6 = new System.Windows.Forms.TreeNode("Top Node", new System.Windows.Forms.TreeNode[] {
treeNode1,
treeNode2,
treeNode3});

现在看起来是这样的：

顶节点 -低节点1 -低节点2 -低节点3 顶节点 -低节点1 -低节点2 -低节点3

如何防止添加此代码？

Answer 1

您可能不应该在自定义控件中这样做。在窗体的构造函数中只在运行时填充TreeView控件会更简单。

如果仍然希望通过自定义控件执行此操作，则只能在not design mode时尝试添加节点。

public SimpleTree() {
  if (LicenseManager.UsageMode != LicenseUsageMode.Designtime) {
    BuildTree();
  }
  this.ExpandAll();
}

另一种可能是只覆盖节点集合，并强制它在设计时不序列化数据：

[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
public new TreeNodeCollection Nodes {
  get {
    return base.Nodes;
  }
}

这将使添加或编辑任何节点在设计时毫无意义，因为它不会保存任何东西。