仿QQ空间相册上下页效果参考JS

<div class="photobox">
<div id="divall" >
<img src="$pic[pic]" id="tu" onmousemove="show_who(this,event)" onclick="click_who()">
</div>
<script>
var pic_url_show=new Array()
var left0=50
var height0=50
var zhang=1
var evt_left,evt_top;
function show_who(o,evt){//alert(o.style.cursor.match("pre"))
evt = evt? evt: window.event;initX = evt.offsetX ? evt.offsetX : evt.layerX;
evt_left=o.clientWidth/2
evt_top=o.clientHeight/2
if(initX <= o.clientWidth/2  && zhang>1){if( o.style.cursor != "url(image/pre.ani),pointer")o.style.cursor = "url(image/pre.ani),pointer";if( o.title != "点击跳到上一张" ){o.title = "点击跳到上一张";}}
else if( o.style.cursor!="url(image/next.ani),pointer"&& zhang<(pic_url_show.length-1)){o.style.cursor="url(image/next.ani),pointer";if( o.title != "点击跳到下一张" ){o.title = "点击跳到下一张";}}
return;
}
function click_who(){
if (event.x<=evt_left){pre();}
else {next();}
}
function next(){
zhang++
if(zhang>=$listpicnum1){zhang=$listpicnum;alert_me("这是最后一张"); document.getElementById("tu").title = ""}
document.getElementById("tu").src=pic_url_show[zhang]
}
function pre(){
zhang--
if(zhang<=0){zhang=1;alert_me("这是第一张"); document.getElementById("tu").title = ""}
document.getElementById("tu").src=pic_url_show[zhang]
}
function alert_me(textis){
var obj_titlel=document.getElementById('titlelayer')
obj_titlel.innerHTML=textis
obj_titlel.style.visibility='visible';
obj_titlel.style.left=evt_left-50;
obj_titlel.style.top=evt_top;
setTimeout ("document.getElementById('titlelayer').style.visibility='hidden';document.getElementById('titlelayer').style.left=-200;",1500)
}
</script>
</div>