$(function(){
    setContainerH(".item_list");
    screenLazyLoad({
        defObj:".item_list"
    });

});
function screenLazyLoad(option) {
    var settings = {
        defObj: null,
        defHeight: 0
    };
    settings = $.extend(settings, option || {});
    var defHeight = settings.defHeight;
    var defObj = (typeof settings.defObj == "object") ? settings.defObj.find("img") : $(settings.defObj).find("img");
    //console.log(len);
    var clientH = document.documentElement.clientHeight;
    var pageTop = function() {
        return clientH + Math.max(document.documentElement.scrollTop, document.body.scrollTop) - settings.defHeight;
    };
    var imgLoad = function() {
        defObj.each(function() {
            var src2 = $(this).data("origin");//已显示的不用再显示
            var styleName = $(this).data('class');
            if ($(this).offset().top <= pageTop()) {               
                if (src2) {                    
                    $(this).attr("src", src2).addClass(styleName).removeAttr('data-origin'); //显示origin属性
                }
            }else{
                $(this).removeClass(styleName);
            }
        });
    };
    imgLoad();
    $(window).bind("scroll", function() {
        imgLoad();
    });
}
function setContainerH(obj){
    var defObj = (typeof obj == "object") ? obj : $(obj);
    var len = defObj.length;
    var clientH = document.documentElement.clientHeight;
    defObj.each(function(i){
        //alert(i);
        if(i < len-1){
            $(this).height(function(h,oldH){ return oldH = clientH-(clientH *0.1)} );  //设置行高；
        }
    });
}