解决图片不能及时展现问题

给图片赋值SRC后，图片不能及时展现，方法如下即可！
function SImage(callback)
{

    var img = new Image();
    this.img = img;
    var appname = navigator.appName.toLowerCase();
    if (appname.indexOf("netscape") == -1)
    {
       //ie
      
        img.onreadystatechange = function () {
  
            if (img.readyState == "complete")
            {
           
                callback(img);
            }
        };
    } else {
       //firefox
alert('fifirfox');
        img.onload = function () {
            if (img.complete == true)
            {
                callback(img);
            }
        }
    }
}

SImage.prototype.get = function (url)
{
    this.img.src = url;
}

function icall(obj)
{
            alert(obj.width);
    cutPic();
    $("#Step2Container").show();


调用方式：
var img2 = new SImage(icall);
  img2.get(img);
}