最近因项目中要用，于是就扩展了TextBox实现输入汉字首字母简单查询。控件扩展代码很简单。但是刚开始，一直没有找到扩展入口，始终无法展现下拉框。先想通过AutoCompleteCustomSource属性改变来实现，但最终没法扩展。后又想到ComboBox但是，也不好控制。经过一天的思考后决定用TextBox + ListBox组合扩展（主要为继承至TextBox和持有ListBox；

效果先上：

 

最要实现代码有：

类原型public class SpellSearchBoxEx : TextBox

{

private ListBox searchList;

.....

1：

 

SpellSearchSource ：查询数据源（汉字）

事件的绑定和选择全在属性里；

public string[] SpellSearchSource

        {

            get { return source; }

            set

            {

                if (value != null)

                {

                    source = value;

                    InitSourceSpell();//实现数据转化为相应拼音并存储；

                    TextChanged += new EventHandler(SpellSearchBoxEx_TextChanged);

                    LostFocus += new EventHandler(SpellSearchBoxEx_LostFocus);

// searchList是一个ListBox，它用来显示下拉框；

                    searchList.KeyDown += new KeyEventHandler(searchList_KeyDown);

                    searchList.Click += new EventHandler(searchList_Click);

                    searchList.MouseMove += new MouseEventHandler(searchList_MouseMove);

                }

 

            }

        }

 

2：TextChanged事件代码

 

 protected virtual void SpellSearchBoxEx_TextChanged(object sender, EventArgs e)
        {
            searchList.Items.Clear();
            string str = this.Text;

            foreach (string var in spellList)
            {
                if (SearchMode == SearchMode.Contains)
                {
                    if (var.IndexOf(str.ToUpper()) != -1)
                    {
                        searchList.Items.Add(source[spellList.IndexOf(var)]);
                    }
                }
                else
                {
                    if (var.ToUpper().StartsWith(str.ToUpper()))
                    {
                        for (int i = 0; i < spellList.Count; i++)
                        {
                            if (spellList[i].Equals(var) && !searchList.Items.Contains(source[i]))
                            {
                                searchList.Items.Add(source[i]);
                            }
                        }
                    }
                }
            }
            if (Regex.IsMatch(str, "[\u4e00-\u9fa5]+"))
            {

                foreach (string var in source)
                {
                    if (SearchMode == SearchMode.Contains)
                    {
                        if (var.ToUpper().IndexOf(str.ToUpper()) != -1 && !searchList.Items.Contains(var))
                        {
                            searchList.Items.Add(var);
                        }
                    }
                    else
                    {
                        if (var.ToUpper().StartsWith(str.ToUpper()) && !searchList.Items.Contains(var))
                        {
                            searchList.Items.Add(var);
                        }
                    }
                }

            }
            SetSearchBoxState();

        }

 

3：控制ListBox的显示和隐藏

        private void SetSearchBoxState()

        {

            if (searchList.Items.Count > 0)

            {

                searchList.BorderStyle = BorderStyle.FixedSingle;

// maxItemCount为下拉框最大显示数；

                searchList.Height = ((searchList.Items.Count >= maxItemCount ? maxItemCount : searchList.Items.Count) + 1) * searchList.ItemHeight;

                searchList.Parent = this.Parent;

                searchList.Location = new System.Drawing.Point(this.Left, this.Bottom);

                searchList.Width = this.Width;

                searchList.BringToFront();

                searchList.Visible = true;

            }

            else

            {

                searchList.Visible = false;

            }

        }

4：剩下的为：控制鼠标滑动和键盘方向键操作，很简单，主要利用ListBox的选中项为高亮显示；及在textBox LostFocus并非ListBox获得焦点时隐藏结果控件ListBox

5：

ListBox上回车或者是点击时提交代码

protected virtual void CommitSearchList()

        {

            if (searchList.SelectedIndex > -1)

            {

                this.Text = searchList.Items[searchList.SelectedIndex].ToString();

                searchList.Visible = false;

                this.Focus();

            }

        }

 

6：主体汉字检索拼音转化代码，见下：很简单，可以直接复制拿来用。

 

 

 

 测试用例及代码