自定义具有自动完成功能的ComboBox

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,根据网上的多个文章试验成功，现将代码贡献出来。

原理：设计一个自定义组件，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。在.net 3.5 vs2008 c#下调试成功。

using System;
using System.ComponentModel;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text;
using System.Collections;
using System.Windows.Forms;
namespace ComBoxtest
{
public partial class AutoComboBox2 : System.Windows.Forms.ComboBox
{
private System.Windows.Forms.ListBox lbMain;
public AutoComboBox2()
{
InitializeComponent();

}

public AutoComboBox2(IContainer container)
{
container.Add(this);

InitializeComponent();
lbMain = new ListBox();
lbMain.Click += new EventHandler(lbMain_Click);
lbMain.KeyDown += new KeyEventHandler(lbMain_KeyDown);
lbMain.Visible = false;
this.Name = "AutoComboBox2";
this.Sorted = true;
this.KeyDown += new System.Windows.Forms.KeyEventHandler(AutoComboBox2_KeyDown);
this.DropDown += new System.EventHandler(AutoComboBox2_DropDown);
this.TextChanged += new System.EventHandler(AutoComboBox2_TextChanged);
this.SelectedIndexChanged += new System.EventHandler(AutoComboBox2_SelectedIndexChanged);
this.Leave += new System.EventHandler(AutoComboBox2_Leave);
}
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;

}

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 AutoComboBox2_DropDown(object sender, System.EventArgs e)
{
lbMain.Visible = false;
}
private void AutoComboBox2_Leave(object sender, System.EventArgs e)
{
if (!lbMain.Focused)
lbMain.Visible = false;
}
private void AutoComboBox2_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 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 AutoComboBox2_SelectedIndexChanged(object sender, System.EventArgs e)
{
lbMain.Visible = false ;
}
private void AutoComboBox2_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;
}
}
}
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);
}

}
}