简单自定义控件

简单自定义控件
decalre SelectedIndexChanged event when create children.

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;

namespace com.csr.rd.jms.webcontrol
{
    /**//// <summary>
    /// Summary description for UC2.
    /// </summary>
    [DefaultProperty("Text"), 
        ToolboxData("<{0}:UC2 runat=server></{0}:UC2>")]
    public class UC2 : System.Web.UI.WebControls.WebControl,INamingContainer,System.Web.UI.IPostBackDataHandler
    {
        private DropDownList F1 = new DropDownList();
        private DropDownList S1 = new DropDownList();
        private Label lblTime = new Label();
    
        [Bindable(true),Category("Appearance"),    DefaultValue("")] 
        
        private void InitDropdownList()
        {
            F1.Width = 70;
            S1.Width = 70;
            
            F1.BackColor = System.Drawing.Color.Azure;
            S1.BackColor = System.Drawing.Color.Beige;
            
        }
        
        public int Index
        {
            get
            {
                return (ViewState["index"] == null)? 0 : int.Parse(ViewState["index"].ToString()) ;
            }
            set
            {
                ViewState["index"] = value;
            }
        }

        private void addItems()
        {
            F1.Items.Add("1");
            F1.Items.Add("2");

            S1.Items.Add("fIRST");
            S1.Items.Add("Second");

        }
        
        protected override void CreateChildControls()
        {
            F1.AutoPostBack = true;
            S1.AutoPostBack = true;
            

            F1.SelectedIndexChanged += new EventHandler(this.F1_SelectedIndexChanged);
            F1.SelectedIndex = Index;

            addItems();
            this.Controls.Add(S1);
            this.Controls.Add(F1);

        }

        protected override void OnInit(EventArgs e)
        {
            //addItems();
            base.OnInit (e);
        }

        
        protected override void Render(HtmlTextWriter output)
        {
//            if(!this.Page.IsPostBack)
//            {
                //addItems();
//            }
            InitDropdownList();
            this.Attributes.AddAttributes(output);
            
            output.AddAttribute(HtmlTextWriterAttribute.Width,"200px");
            output.RenderBeginTag(HtmlTextWriterTag.Table);
            output.RenderBeginTag(HtmlTextWriterTag.Tr);
            output.RenderBeginTag(HtmlTextWriterTag.Td);

            F1.RenderControl(output);
            S1.RenderControl(output);

            output.RenderEndTag();
            output.RenderEndTag();
            output.RenderEndTag();
            //output.Write(Text);
        }

        private void F1_SelectedIndexChanged(object sender, EventArgs e)
        {
            S1.SelectedIndex = F1.SelectedIndex;
            ViewState["index"] = F1.SelectedIndex.ToString();

        }

        public void RaisePostDataChangedEvent()
        {
            // TODO:  Add CommonCalendar.RaisePostDataChangedEvent implementation
        }

        public bool LoadPostData(string postDataKey, System.Collections.Specialized.NameValueCollection postCollection)
        {
            return true;
        }
    }
}