在Winforms的富文本框中逐字撤消和重做

using System;
using System.Collections.Generic;
using System.Windows.Forms;

public class CustomRichTextBox : RichTextBox
{
    private Stack<string> undoStack = new Stack<string>();
    private Stack<string> redoStack = new Stack<string>();

    protected override void OnTextChanged(EventArgs e)
    {
        base.OnTextChanged(e);
        if (!isUndoing && !isRedoing)
        {
            undoStack.Push(Text);
            redoStack.Clear();
        }
    }

    private bool isUndoing = false;
    private bool isRedoing = false;

    public void Undo()
    {
        isUndoing = true;
        if (undoStack.Count > 1)
        {
            redoStack.Push(undoStack.Pop());
            Text = undoStack.Peek();
        }
        isUndoing = false;
    }

    public void Redo()
    {
        isRedoing = true;
        if (redoStack.Count > 0)
        {
            undoStack.Push(redoStack.Pop());
            Text = undoStack.Peek();
        }
        isRedoing = false;
    }
}

public partial class MainForm : Form
{
    private CustomRichTextBox richTextBox;

    public MainForm()
    {
        InitializeComponent();
        richTextBox = new CustomRichTextBox();
        richTextBox.Dock = DockStyle.Fill;
        Controls.Add(richTextBox);

        Button undoButton = new Button { Text = "Undo", Dock = DockStyle.Left };
        undoButton.Click += (sender, e) => richTextBox.Undo();
        Controls.Add(undoButton);

        Button redoButton = new Button { Text = "Redo", Dock = DockStyle.Left };
        redoButton.Click += (sender, e) => richTextBox.Redo();
        Controls.Add(redoButton);
    }
}