在GridView中实现提示文本隐藏

在GridView中要实现这样的样式
<asp:TemplateField HeaderText="退">
                                    <ItemTemplate>
                                        <asp:Label ID="Label1" runat="server" Text='<%# CutString(Convert.ToString(Eval("CancelInfo")),20) %>'
                                            ToolTip='<%# Bind("CancelInfo") %>'></asp:Label>
                                    </ItemTemplate>


在代码中，加入这样的方法

 /// 按字符串实际长度截取定长字符窜
    /// </summary>
    /// <param name="str">原字符串</param>
    /// <param name="length">要截取的长度</param>
    /// <returns>string型字符串</returns>
    protected string CutString(string str, int length)
    {
        string delsqace = str.Trim();
        int i = 0, j = 0;
        foreach (char chr in delsqace)
        {

            if ((int)chr > 127)
            {
                i += 2;
            }
            else
            {
                i++;
            }
            if (i > length)
            {
                delsqace = delsqace.Substring(0, j) + "...";
                break;
            }
            j++;
        }
        return delsqace;

    }