可输入下拉框，完美版，asp.net
最近很是郁闷，一个可输入的下拉框搞了我好几天，开始的时候在网上找到一个服务器控件，用了一下，发现满足不了自己的需求。于是乎花了几个小时改了改，终于成形。这个控件和别人不同有以下两点：
1,一般的dropdownlist都会默认选中第一条，这样的话，在选择第一条的时候就没有事件，而往往这时候我们需要触发ongchange事件，于是我在它的foucus事件中强行改变它的selectedIndex。
2，输入的内容如果和下拉框中的某项相同时，会自动选中下拉框中那一条。
using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;
using System.Collections;
namespace ExtendWebControls
{
[ToolboxData("<{0}:DropDownListExtend runat=\"server\" />")]
public class DropDownListExtend : System.Web.UI.WebControls.TextBox
{
private Hashtable _values;
private DropDownList _DropDownList;
public DropDownListExtend()
{
_values = new Hashtable();
_DropDownList = new DropDownList();
}
public Hashtable Values
{
get{return _values;}
set{_values = value;}
}
protected override void Render(HtmlTextWriter output)
{
int iWidth = Convert.ToInt32(base.Width.Value);
if(iWidth == 0)
{
iWidth = 102;
base.Width = Unit.Parse("102px");
}
int sWidth = iWidth + 16;
int spanWidth = sWidth - 18;
output.Write("<div POSITION:relative\">");
output.Write("<span MARGIN-LEFT:" + spanWidth.ToString() + "px;OVERFLOW:hidden;WIDTH:18px\">");
_DropDownList.Width = Unit.Parse(sWidth.ToString() + "px");
_DropDownList.Style.Add("MARGIN-LEFT", "-" + spanWidth.ToString() + "px");
_DropDownList.ID = base.ID + "_Select";
_DropDownList.Attributes.Add("onchange", "this.parentNode.nextSibling.value=this.value");
_DropDownList.Attributes.Add("onfocus", ""+this.getFocusScript()+"");
if(_values.Count > 0)
{
foreach(string key in _values.Keys)
{
ListItem item = new ListItem();
item.Value = key;
item.Text = _values[key].ToString();
_DropDownList.Items.Add(item);
}
}
_DropDownList.RenderControl(output);
output.Write("</span>");
base.Style.Clear();
base.Width = Unit.Parse(iWidth.ToString() + "px");
base.Style.Add("left", "0px");
base.Style.Add("POSITION", "absolute");
base.Render(output);
output.Write("</div>");
}
private string getFocusScript()
{
string strScript = "\n";
strScript += "var isExist = -2;\n";
strScript += "var obj = event.srcElement;\n";
strScript += "var str = this.parentNode.nextSibling.value;\n";
strScript += "var ary = obj.options;\n";
strScript += "for(var i=0;i<ary.length;i++){\n";
strScript += " if(str == ary[i].text){\n";
strScript += " isExist = i;\n";
strScript += " break;\n";
strScript += " }\n";
strScript += "}\n";
strScript += "if(isExist != -2){\n";
strScript += " obj.selectedIndex = isExist;\n";
strScript += "}\n";
strScript += "else{\n";
strScript += " obj.selectedIndex = -1;\n";
strScript += "}\n";
return strScript;
}
}
}
