var div_pics_scroll;
var btnpre;
var btnnext;
var currt_scrollleft;
var speed=10;
var MyMar;//左滚动
var MyMarR;//右滚动
var MyMarToCurr;
var img_width=240;//$("#div_pics_scroll")[0].width;//图片的宽度
var scolldivwidth=240;//div的宽度
var scroll=false ;
var ccrollcount=1;//滚动个数  初始化时用
var onececroll=1;//一次滚动几个
function picinit(cur,count)
{
  div_pics_scroll=$("div_pics_scroll");
  btnpre=$("btnpre");
  btnnext=$("btnnext");
  if(cur<=1)
   ;//btnnext.className='btn2';
  else
  {
   btnnext.className='btn4';//可用
   ccrollcount=parseInt(cur/4)*4;
   picToCurr();
  }
  if(cur+1>=count)
   ;//btnpre.className='btn1';
  else
   ;// btnpre.className='btn3';//可用
}
var $ = function (id) {
    return "string" == typeof id ? document.getElementById(id) : id;
};
function picpres(obj){ startR();}
function picNext(obj){startL();}
function picToCurr() { startC();};
function overl() {clearInterval(MyMar);MyMar=null; ChoosepreSate();scroll=false;}
function startL() { if(!scroll){ MyMar=setInterval(Marquee,speed);currt_scrollleft=div_pics_scroll.scrollLeft;scroll=true ;}}
function overR() {clearInterval(MyMarR);MyMarR=null; ChoosepreSate();scroll=false ;}
function startR() {if(!scroll){ MyMarR=setInterval(MarqueeR,speed);currt_scrollleft=div_pics_scroll.scrollLeft;scroll=true ;}}
function overC() {clearInterval(MyMarToCurr);MyMarToCurr=null; ChoosepreSate();scroll=false ;}
function startC() {if(!scroll){ MyMarToCurr=setInterval(MarqueeC,speed);currt_scrollleft=div_pics_scroll.scrollLeft;scroll=true ;}}
 //向左滚动 
function Marquee(){
      if(div_pics_scroll.scrollLeft<(currt_scrollleft+onececroll*img_width)&&(div_pics_scroll.scrollLeft+scolldivwidth)<div_pics_scroll.scrollWidth)
      { 
        if((div_pics_scroll.scrollLeft+5)>(currt_scrollleft+onececroll*img_width))
          div_pics_scroll.scrollLeft=currt_scrollleft+onececroll*img_width;
        else div_pics_scroll.scrollLeft+=5;}
      else
      {overl();}
  }
  //滚到指定位置
  function MarqueeC(){
      if(div_pics_scroll.scrollLeft<(currt_scrollleft+ccrollcount*img_width)&&(div_pics_scroll.scrollLeft+scolldivwidth)<div_pics_scroll.scrollWidth)
      { 
        if((div_pics_scroll.scrollLeft+5)>(currt_scrollleft+ccrollcount*img_width))
          div_pics_scroll.scrollLeft=currt_scrollleft+ccrollcount*img_width;
        else div_pics_scroll.scrollLeft+=5;}
      else
      {overC();}
  }
  //向右滚动
   function MarqueeR(){
             if(div_pics_scroll.scrollLeft>(currt_scrollleft-onececroll*img_width)&&div_pics_scroll.scrollLeft>0)
             {
               if((div_pics_scroll.scrollLeft-5)<(currt_scrollleft-onececroll*img_width))
                 div_pics_scroll.scrollLeft=currt_scrollleft-onececroll*img_width;
              else div_pics_scroll.scrollLeft-=5;
             }
             else
             {
               overR();
             }
  }
  function ChoosepreSate()
  {
   if((div_pics_scroll.scrollLeft+scolldivwidth)<div_pics_scroll.scrollWidth)
    {btnnext.onclick=function (){picNext(this);};
    // btnpre.className='btn3';
    }
    else
    { btnnext.onclick=function (){};
     //btnpre.className='btn1';
     }
    if(div_pics_scroll.scrollLeft>0)
    {  btnpre.onclick=function (){picpres(this);};
    //btnnext.className='btn2';
    }
    else
     {
     btnpre.onclick=function (){};
     //btnnext.className='btn4';
     }
 
  }