在自定义控件中未从嵌套控件触发Asp.net Web Forms事件

我有一个继承GridView的自定义控件。我还编写了一个继承BoundField的类，以创建一个将图像显示到ButtonClick控件中的列。当我点击这个"图像列"时，它会引发一个事件。在第一个GridView自定义控件中，我绑定了"图像列点击"事件。它永远不会被触发。

图片列代码:

using System.Web.UI;
using System.Web.UI.WebControls;
using WebControls.Infrastructure;
namespace WebControls
{
    public class DataSearchGridImageColumn : BoundField
    {
        public event StringDelegate ImageClicked;
        public string ImageUrl
        {
            get
            {
                return (string)ViewState["ImageUrl"] ?? string.Empty;
            }
            set
            {
                ViewState["ImageUrl"] = value;
            }
        }
        protected override void InitializeDataCell(DataControlFieldCell cell, DataControlRowState rowState)
        {
            var img = new ImageButton
            {
                ID = "ImgSelectRecord",
                ImageUrl = ImageUrl,
            };
            cell.Controls.Add(img);
            img.Click += ImgClick;
        }
        void ImgClick(object sender, ImageClickEventArgs e)
        {
            var img = sender as ImageButton;
            if (img == null) return;
            var row = (GridViewRow)img.NamingContainer;
            if (row == null) return;
            // get the id
            var id = row.Cells[1].Text;

            // raise an event
            OnClick(id);
        }
        protected virtual void OnClick(string id)
        {
            if (ImageClicked != null)
            {
                ImageClicked(this, id);
            }
        }
    }
}

绑定事件的数据视图自定义控件代码:

protected override void OnDataBinding(EventArgs e)
{
    // create a new page because the Page object is null in this context
    var pg = new Page();
    var selectionColumn = new DataSearchGridImageColumn
    {
        ImageUrl = string.Format(
            "url({0})",
            pg.ClientScript.GetWebResourceUrl(GetType(), "WebControls.Images.search.png"))
    };

    Columns.Clear();
    Columns.Add(selectionColumn);
    Columns.Add(CreateColumn(ValueFieldName, ValueFieldName));
    Columns.Add(CreateColumn(TextFieldName, TextFieldName));
    AutoGenerateColumns = false;
    selectionColumn.ImageClicked += SelectionColumnImageClicked;
    base.OnDataBinding(e);
}
void SelectionColumnImageClicked(object sender, string value)
{
    if (RowSelected != null)
        RowSelected(this, value);
}