具有自动完成功能的ComboBox（源码、原创）

根据你输入的内容自动过滤出匹配的列表项，并实时显示出来，和IE地址栏类似。
程序很简单，只是很长事时间没更新blog了，用这篇小文章来更新一下。

程序原理是这样的：组件继承之combobox，并且拥有一个listbox成员，当组件的text改变时，就从combobox中过滤出匹配的列表项，并且把这些列表项加入到listbox中显示出来。
演示效果：
using System;

using System.Collections;

using System.ComponentModel;

using System.Drawing;

using System.Data;

using System.Windows.Forms;

 

namespace XPangLib

{

     /// <summary>

     /// AutoComboBox 的摘要说明。

     /// </summary>

     public class AutoComboBox : System.Windows.Forms.ComboBox

     {

 

          private System.Windows.Forms.ListBox lbMain;

         /// <summary>

         /// 必需的设计器变量。

         /// </summary>

          private System.ComponentModel.Container components = null;

 

         public AutoComboBox()

         {

              // 该调用是 Windows.Forms 窗体设计器所必需的。

              InitializeComponent();

 

              lbMain = new ListBox() ;

              lbMain.Click+=new EventHandler(lbMain_Click);

              lbMain.KeyDown+=new KeyEventHandler(lbMain_KeyDown);

              lbMain.Visible = false ;         

         }

         /// <summary>

         /// 得到匹配给定字符串的列表

         /// </summary>

          private ArrayList GetFillList(string strValue)

         {

              ArrayList alReturn = new ArrayList() ;

              int iCount = this.Items.Count ;

              int iLen = strValue.Length ;

 

              for(int i = 0 ;i < iCount ;i++)

              {

                   string strSelItem = this.Items[i].ToString() ;

 

                   if (strSelItem.Length < iLen)

                        continue ;

 

                   if (strSelItem.Substring(0,iLen) == strValue)

                   alReturn.Add(strSelItem) ;

              }

             

              return alReturn ;

         }

         /// <summary>

         /// 清理所有正在使用的资源。

         /// </summary>

          protected override void Dispose( bool disposing )

         {

              if( disposing )

              {

                   if( components != null )

                        components.Dispose();

              }

              base.Dispose( disposing );

         }

 

          #region 组件设计器生成的代码

         /// <summary>

         /// 设计器支持所需的方法 - 不要使用代码编辑器

         /// 修改此方法的内容。

         /// </summary>

          private void InitializeComponent()

         {//

              // AutoComboBox

              //

              this.Sorted = true;

              this.KeyDown += new System.Windows.Forms.KeyEventHandler(this.AutoComboBox_KeyDown);

              this.DropDown += new System.EventHandler(this.AutoComboBox_DropDown);

              this.TextChanged += new System.EventHandler(this.AutoComboBox_TextChanged);

              this.SelectedIndexChanged += new System.EventHandler(this.AutoComboBox_SelectedIndexChanged);

              this.Leave += new System.EventHandler(this.AutoComboBox_Leave);

 

         }

          #endregion

 

          protected override void OnPaint(PaintEventArgs pe)

         {

              // TODO: 在此添加自定义绘画代码

 

              // 调用基类 OnPaint

              base.OnPaint(pe);

         }

          private void lbMain_Click(object sender, System.EventArgs e)

         {

              if (lbMain.SelectedItems.Count == 0)

                   return ;

              string strSel = lbMain.SelectedItem.ToString() ;

              this.Text = strSel ;

              int iSel = this.FindStringExact(Text) ;

              if (iSel != -1)

                   this.SelectedIndex = iSel ;

              lbMain.Visible = false ;

         }

          private void AutoComboBox_TextChanged(object sender, System.EventArgs e)

         {

              if (Text == "")

              {

                   lbMain.Visible = false ;

                   return ;

              }

              if (!this.Parent.Controls.Contains(lbMain))

              {

                   lbMain.Width = this.Width ;

                   lbMain.Height = 100 ;

                   lbMain.Parent = this.Parent ;

                   lbMain.Top = this.Top + this.Height + 1 ;

                   lbMain.Left = this.Left ;

                   this.Parent.Controls.Add(lbMain);

                   lbMain.BringToFront() ;

              }

              ArrayList alFill  = GetFillList(Text) ;

              lbMain.Items.Clear() ;

              lbMain.Items.AddRange(alFill.ToArray()) ;

              if (lbMain.Items.Count > 0)

                   lbMain.SelectedIndex = 0 ;

              if (!lbMain.Visible)

                   lbMain.Visible = true ;

         }

 

          private void AutoComboBox_Leave(object sender, System.EventArgs e)

         {

              if (!lbMain.Focused)

                   lbMain.Visible = false ;

         }

 

          private void AutoComboBox_DropDown(object sender, System.EventArgs e)

         {

              lbMain.Visible = false ;

         }

 

          private void AutoComboBox_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)

         {

              if (lbMain.Visible)

              {

                   if (e.KeyCode == Keys.Up||e.KeyCode == Keys.Down||e.KeyCode == Keys.Left||

                        e.KeyCode == Keys.Right||e.KeyCode == Keys.PageDown||e.KeyCode == Keys.PageUp)

                   {

                        lbMain_KeyDown(lbMain,e) ;

                        e.Handled = true ;                

                   }

                   else if (e.KeyCode == Keys.Enter)

                   {

                        lbMain_Click(lbMain,e) ;

                        e.Handled = true ;  

                   }

              }

         }

          private void lbMain_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)

         {

        

              if (e.KeyCode == Keys.Up||e.KeyCode == Keys.Left||e.KeyCode == Keys.PageUp)

              {

                   if (lbMain.SelectedIndex > 0)

                        lbMain.SelectedIndex = lbMain.SelectedIndex - 1 ;

              }

              else if (e.KeyCode == Keys.Down||e.KeyCode == Keys.Right||e.KeyCode == Keys.PageDown)

              {

                   if (lbMain.SelectedIndex < lbMain.Items.Count - 1)

                        lbMain.SelectedIndex = lbMain.SelectedIndex + 1 ;

              }

         }

 

          private void AutoComboBox_SelectedIndexChanged(object sender, System.EventArgs e)

         {

              lbMain.Visible = false ;

         }

     }//end class

}//end namespace

 

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