CS模式下的自动填充框（高效率，解决输入法多次回发问题并进行延迟处理）

最新推荐文章于 2025-08-03 09:19:30 发布

原创最新推荐文章于 2025-08-03 09:19:30 发布 · 479 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#CS-自动填充框 #扩展 #class #textbox

C# 专栏收录该内容

5 篇文章

订阅专栏

本文介绍了一个使用自定义扩展方法来实现文本框自动补全功能的技术，通过创建一个单独线程来实时更新下拉列表，为用户提供更便捷的输入体验。该方法包括初始化下拉列表、事件监听以及输入处理逻辑。

====TextBox扩展方法======

public static class Extend
    {
        /// <summary>
        /// 自动填充box框
        /// </summary>
        /// <param name="tb"></param>
        /// <param name="fun">提供当前输入字符，要求返回查询出的列表，此操作在单独线程中进行</param>
        /// <param name="act">当前选中的对象</param>
        public static void AutoComplete(this TextBox tb, Func<string, List<object>> fun, Action<object> act)
        {
            var lbID = tb.Name + "_AutoComplete";
            var bContinue = true;

            if(tb.Parent.Controls.ContainsKey(lbID))
                throw new Exception("不可重复绑定自动填充控件");

            ListBox lb = new ListBox();
            lb.Name = lbID;

            lb.Location = new Point(tb.Location.X,tb.Location.Y + tb.Height + 1);
            lb.Visible = false;
            lb.Width = tb.Width;
            lb.Height = 0;
            lb.HorizontalScrollbar = false;

            lb.DoubleClick += (oo, ee) => 
            { 
                lb.Visible = false; 
                act(lb.SelectedItem); 
            };

            tb.Parent.Controls.Add(lb);

            ManualResetEvent mrevent = new ManualResetEvent(false);

            Thread thread = new Thread((o) => 
            {
                while (true)
                {
                    if(bContinue == false)
                        break;

                    mrevent.Reset();
                    mrevent.WaitOne();

                    Thread.Sleep(200);

                    if (tb.Text.Trim() == string.Empty)
                    {
                        lb.Visible = false;
                        lb.Items.Clear();
                        continue;
                    }

                    var list = fun(tb.Text);

                    if (list.Count == 0)
                        continue;

                    Action act2 = () => 
                    {
                        lb.Items.Clear();
                        lb.BringToFront();
                        lb.Visible = true;
                        lb.Height = lb.ItemHeight * (list.Count + 1) + 2;
                        lb.Items.AddRange(list.ToArray());
                    };
                    lb.Invoke(act2);
                }
            });

            thread.IsBackground = true;
            thread.Start();

            tb.KeyDown += (o, e) => 
            {
                if (lb.Visible == false || lb.Items.Count == 0)
                    return;

                if (e.KeyCode != Keys.Up && e.KeyCode != Keys.Down && e.KeyCode != Keys.Enter)
                    return;

                var index = lb.SelectedIndex >= 0 ? lb.SelectedIndex : -1;

                if (e.KeyCode == Keys.Up)
                    index--;

                else if (e.KeyCode == Keys.Down)
                    index++;

                if (index == lb.Items.Count)
                    index = lb.Items.Count - 1;
                else if (index == -1)
                    index = 0;

                lb.SelectedIndex = index;
                tb.Focus();

                if (e.KeyCode == Keys.Enter)
                {
                    lb.Visible = false; 
                    act(lb.SelectedItem);
                }
            };

            tb.KeyUp += (o, e) => 
            {
                if (e.KeyCode != Keys.Up && e.KeyCode != Keys.Down)
                    return;

                tb.SelectionLength = 0;
                tb.SelectionStart = tb.Text.Length + 3;
            };

            tb.TextChanged += (o, e) => 
            {
                if (tb.Text.Trim() == string.Empty)
                {
                    lb.Visible = false;
                    lb.Items.Clear();
                    return;
                }

                mrevent.Set();
            };

            tb.Disposed += (o, e) => 
            {
                lb.Dispose();
                bContinue = false;
                mrevent.Set();
            };
        }
    }

========实例==========

public partial class AutoCompleteBoxPanle : Form
    {
        public AutoCompleteBoxPanle()
        {
            InitializeComponent();

            CheckForIllegalCrossThreadCalls = false;

            textBox1.AutoComplete(s => { 
                return new List<object>() { s + "@163.com", s + "@sina.com", s + "@qq.com" }; 
            }, s => 
                MessageBox.Show(s.ToString()));
        }
    }