I read the whole article and figured that i am doing something like this.Here is code of my custom control.
using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;
using System.Text;
using System.Collections;
using System.Collections.Specialized;
namespace DropDownWebControl
{
/// <summary>
/// Summary description for WebCustomControl1.
/// </summary>
[DefaultProperty("Text"),
ToolboxData("<{0}:SmartDropDown runat=server></{0}:SmartDropDown>")]
public class SmartDropDown : System.Web.UI.WebControls.DropDownList,IPostBackDa taHandler, IPostBackEventHandler
{
private string text;
[Bindable(true),
Category("Appearance"),
DefaultValue("")]
private Boolean isLoaded = false;
public object EventServerChange;
public event EventHandler SelectedIndexChanged;
public string Text
{
get
{
return text;
}
set
{
text = value;
}
}
protected virtual void OnSelectedIndexChanged(EventArgs e)
{
if (SelectedIndexChanged != null)
SelectedIndexChanged(this,e);
}
/// <summary>
/// Render this control to the output parameter specified.
/// </summary>
/// <param name="output"> The HTML writer to write out to </param>
protected override void Render(HtmlTextWriter output)
{
Page.GetPostBackEventReference(this, "OnSelectedIndexChanged");
output.AddAttribute(HtmlTextWriterAttribute.Type, "text");
output.AddAttribute(HtmlTextWriterAttribute.Value, this.Text);
output.AddAttribute(HtmlTextWriterAttribute.Name, this.UniqueID);
output.RenderBeginTag(HtmlTextWriterTag.Input);
output.RenderEndTag();
}
protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);
Page.RegisterClientScriptBlock("SmartDropDownScrip t", GetScriptBlock());
}
protected void RenderBaseControl(System.Web.UI.HtmlTextWriter output)
{
base.Attributes["onKeypress"] = "return (dodefaultaction()==''); ";
base.Attributes["onKeydown"] = "return (dodefaultaction()==''); ";
base.Attributes["onKeyup"] = "return (change(" + base.ClientID + "));";
base.Attributes["onfocus"] = "txtval = '';";
base.Attributes["onblur"] = "txtval = '';";
base.Render(output);
}
protected virtual void RenderAttributes(HtmlTextWriter writer)
{
if (base.ID != null)
{
writer.WriteAttribute("id", base.ClientID);
writer.WriteAttribute("name", this.UniqueID);
}
if (!this.Enabled)
writer.WriteAttribute("Enabled","false");
writer.WriteAttribute("ParentFormID", this.ClientID);
if (this.AutoPostBack)
{
string sOnChangeCmd = this.Attributes["onchange"];
if (sOnChangeCmd != null)
{
this.Attributes["onchange"] = (sOnChangeCmd.EndsWith(";")) ? sOnChangeCmd + Page.GetPostBackEventReference(this, String.Empty)+ ";" : sOnChangeCmd + ";" + Page.GetPostBackEventReference(this, String.Empty);
}
else
{
this.Attributes.Add("onchange", Page.GetPostBackEventReference(this, String.Empty));
}
}
this.Attributes.Render(writer);
}
protected void RenderHiddenInput(System.Web.UI.HtmlTextWriter output)
{
output.Write("<input type='hidden' value='' name='hidden" + base.ClientID + "'>");
}
protected string GetScriptBlock()
{
string sReturn= "<SCRIPT>";
sReturn += "var txtval = '';";
sReturn += "var curlist;";
sReturn += "function select(trigger){ ";
sReturn += "curlist=trigger;";
sReturn += "for (n=0;n<curlist.length;n++){";
sReturn += "if(curlist[n].text.toLowerCase().indexOf(txtval.toLowerCase())= =0){";
sReturn += "curlist.selectedIndex=n;break;";
sReturn += " }else{";
sReturn += " if (n==curlist.length-1) txtval=''; curlist.selectedIndex=0;}}}";
sReturn += "function dodefaultaction(e){ ";
sReturn += "var code; ";
sReturn += "if (!e) var e = window.event; ";
sReturn += "if (e.keyCode) code = e.keyCode; ";
sReturn += "else if (e.which) code = e.which;";
//sReturn += "if(code == '9' | code == '40' | code == '38') return ''; ";
sReturn+="if(code=='13') alert('enter hit!');";
sReturn += "else return code;}";
sReturn += "function change(trigger){ ";
sReturn += "var code = dodefaultaction(); ";
sReturn += "if(code == ''){ txtval='';return false;} ";
sReturn+="else if(code=='13'){";
sReturn+="__doPostBack('"+this.ClientID+"','');}";
sReturn += "else{";
sReturn += "if(code == '8'){ alert ('backspace');txtval='';} ";
sReturn += "else{";
sReturn += "txtval = txtval + String.fromCharCode(code);}select(trigger); return true;}}</SCRIPT>";
return sReturn;
}
public void RaisePostBackEvent(String eventArgument)
{
if (eventArgument == null)
{
return;
}
}
public virtual void RaisePostDataChangedEvent()
{
this.OnSelectedIndexChanged(EventArgs.Empty);
}
public virtual bool LoadPostData(string postDataKey, NameValueCollection postCollection)
{
string sValue = Text;
string sPostedValue = postCollection[postDataKey];
if (!sPostedValue.Equals(sValue))
{
Text = sPostedValue;
return true;
}
return false;
}
}
}
