function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      oldonload();
      func();
    }
  }
}
function setImgSize(img,width,height){
var MaxWidth=width;//设置图片宽度界限
var MaxHeight=height;//设置图片高度界限
var HeightWidth=img.offsetHeight/img.offsetWidth;//设置高宽比
var WidthHeight=img.offsetWidth/img.offsetHeight;//设置宽高比
if(img.offsetWidth>MaxWidth){
img.width=MaxWidth;
img.height=MaxWidth*HeightWidth;
}
if(img.offsetHeight>MaxHeight){
img.height=MaxHeight;
img.width=MaxHeight*WidthHeight;
}

}
function changPic(){
var myID=document.getElementById("pictextcont").getElementsByTagName("img");
for(var i=0;i<myID.length;i++){	
setImgSize(myID[i],600,600);
}
}
addLoadEvent(changPic);