Why do I get the result zero when I try to get the width of a DropDownList control in asp.net?
After I click button1, it display 0, why? How can get correct width of a DropDownList control? Thanks!
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Button ID="Button1" runat="server" Text="Button" />
<asp:DropDownList ID="DropDownList1" runat="server">
<asp:ListItem>Item 1</asp:ListItem>
<asp:ListItem>Item 2</asp:ListItem>
</asp:DropDownList>
</div>
</form>
</body>
</html>
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class Default2 : S开发者_运维百科ystem.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
Button1.Text = DropDownList1.Width.Value.ToString();
}
}
It's because the value Width is not set. In html, when the width value is not set, you let the browser choose the size.
Moreover, the asp.net engine only host properties to be able to render the correct Html. If you look at the code of the textbox, you will see that if you put a witdh, it will produces a style="width:yourvalue". ASP.net runs on the server side, so it do not have any idea of the actual size of the control.
If you actually require the client size of the dropdownlist, either specify it explicitly, or use some custom javascript to calculate the actual size of the control, then to pass the calculted size to an hidden field. In the code behind you be able to get the value from the Page.Request.Form collection. Please clarify your need if you need further explanation.
加载中,请稍侯......
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