C#代码

using System;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.ComponentModel;

 

using System.Text;

 

namespace Controls

{

    /// <summary>

    /// MyTextBox2 的摘要说明。

    /// </summary>

    [ToolboxData("<{0}:MyTextBox2 runat=server></{0}:MyTextBox2>")]

    public class MyTextBox2 : System.Web.UI.WebControls.WebControl,INamingContainer

    {

        private Label lbl;

        private TextBox txt;

 

        protected override void CreateChildControls()

        {

            base.CreateChildControls ();

 

            lbl = new Label();

            lbl.ID = "lbl";

            lbl.Style.Add("display", "none");

            Controls.Add(lbl);

 

            txt = new TextBox();

            txt.ID = "txt";

            txt.AutoPostBack = true;

            txt.TextChanged += new EventHandler(txt_TextChanged);

            Controls.Add(txt);

 

            lbl.Attributes.Add("onclick", "showbox(this,'" + txt.ClientID + "');");

 

            ChildControlsCreated = true;

        }

 

        protected override void OnPreRender(EventArgs e)

        {

            base.OnPreRender (e);

            if(txt.Text.Trim().Length == 0)

                return;

            double t = 0;

            try

            {

                t = double.Parse(txt.Text.Trim());

            }

            catch(Exception ex)

            {

                ex.ToString();

            }

            lbl.Text = t.ToString("c");

        }

 

 

        protected override void RenderChildren(HtmlTextWriter writer)

        {

            StringBuilder sb = new StringBuilder();

 

            sb.Append("<script language='javascript'>");

            sb.Append("function showbox(lbl,txtID){lbl.style.display='none';var txt=document.getElementById(txtID);txt.style.display='block';}");

            sb.Append("</script>");

 

            this.Page.RegisterStartupScript("MyTextBox2JS", sb.ToString());

 

            lbl.RenderControl(writer);

            txt.RenderControl(writer);

        }

 

        protected override HtmlTextWriterTag TagKey

        {

            get

            {

                return HtmlTextWriterTag.Div;

            }

        }

 

        private void txt_TextChanged(object sender, EventArgs e)

        {

            if(txt.Text.Trim().Length == 0)

                return;

            double t = 0;

            try

            {

                t = double.Parse(txt.Text.Trim());

            }

            catch(Exception ex)

            {

                ex.ToString();

            }

            lbl.Style.Add("display", "block");

            lbl.Text = t.ToString("c");

            txt.Style.Add("display", "none");

        }

    }

}