How to know which control has raised a postback?

public string GetPostBackControl(System.Web.UI.Page page)

    {

        Control ctrl1 = null;

        Control ctrl2 = null;

        string ctrlName = page.Request.Params["__EVENTTARGET"];

        string ctrlStr = string.Empty;

        if (ctrlName != null && ctrlName != String.Empty)

        {

            ctrl1 = page.FindControl(ctrlName);

        }

        else

        {

            foreach (string ctl in page.Request.Form)

            {

                if (ctl.EndsWith(".x") || ctl.EndsWith(".y"))

                {

                    ctrlStr = ctl.Substring(0, ctl.Length - 2);

                    ctrl2 = page.FindControl(ctrlStr);

                }

                else

                {

                    ctrl2 = page.FindControl(ctl);

                }

                if (ctrl2 is System.Web.UI.WebControls.Button || ctrl2 is System.Web.UI.WebControls.ImageButton)

                {

                    ctrl1 = ctrl2;

                    break;

                }

            }

        }

        return ctrl1.ClientID;

    }