var viewer=new Class({
mode:'rand',
modes:['alpha'],
sizes:{w:480,h:210},
fxOptions:{duration:1000},
interval:2000,

    initialize:function(a,b){if(b)for(var o in b)this[o]=b[o];
    if(this.buttons){this.buttons.previous.addEvent('click',this.previous.bind(this,[true]));
    this.buttons.next.addEvent('click',this.next.bind(this,[true]))}this._current=0;
    this._previous=null;this.items=a.setStyle('display','none');
    this.items[this._current].setStyle('display','block');
    this.disabled=false;
    this.attrs={
    left:['left',-this.sizes.w,0,'px'],
    top:['top',-this.sizes.h,0,'px'],
    right:['left',this.sizes.w,0,'px'],
    bottom:['top',this.sizes.h,0,'px'],
    alpha:['opacity',0,1,'']
    };
    this.rand=this.mode=='rand';this.sequence=typeof(this.mode)=='object'?this.mode:false;this.curseq=0;this.timer=null},walk:function(n,b){if(this._current!==n&&!this.disabled){this.disabled=true;if(b){this.stop()}if(this.rand){this.mode=this.modes.getRandom()}else if(this.sequence){this.mode=this.sequence[this.curseq];this.curseq+=this.curseq+1<this.sequence.length?1:-this.curseq}this._previous=this._current;this._current=n;var a=this.attrs[this.mode].associate(['p','f','t','u']);for(var i=0;i<this.items.length;i++){if(this._current===i){this.items[i].setStyles($extend({'display':'block','z-index':'2'},JSON.decode('{"'+a.p+'":"'+a.f+a.u+'"}')))}else if(this._previous===i){this.items[i].setStyles({'z-index':'1'})}else{this.items[i].setStyles({'display':'none','z-index':'0'})}}this.items[n].set('tween',{onComplete:this.onComplete.bind(this)}).tween(a.p,a.f,a.t)}},play:function(a){this.stop();if(!a){this.next()}this.timer=this.next.periodical(this.interval,this,[false])},stop:function(){$clear(this.timer)},next:function(a){this.walk(this._current+1<this.items.length?this._current+1:0,a)},previous:function(a){this.walk(this._current>0?this._current-1:this.items.length-1,a)},onComplete:function(){this.disabled=false;this.items[this._previous].setStyle('display','none');if(this.onWalk)this.onWalk(this._current)}});