/*
* Copyright (C) 2007-2009 skylark
* Email:aohailin@gmail.com
* Version:2.1
* 原創(chuàng)程序,轉(zhuǎn)載請(qǐng)保留版權(quán)
*/
var $=function(o){return typeof o=="string"?document.getElementById(o):o;};
function AutoScroll(){
this.obj=[];
this.version="2.1";
this.Build();//初始化
};
AutoScroll.prototype.Build=function(){
var me=this;
//取得其他滾動(dòng)事件
var oldscroll=window.onscroll;
window.onscroll=function(){
//保護(hù)其他滾動(dòng)事件
if("function"==typeof oldscroll){
oldscroll();
}
//得到客戶端瀏覽器參數(shù),兼容IE，F(xiàn)F，Chrome
this.common={
t:document.documentElement.scrollTop||document.body.scrollTop,
h:document.documentElement.clientHeight||document.body.clientHeight,
w:document.documentElement.clientWidth||document.body.clientWidth
};
this.position=[];
for(var i=0;i<me.obj.length;i++){
try{
this.style={};
//獲得客戶端位置,設(shè)置了7種位置
//為了讓最小化自動(dòng)適應(yīng)位置,這里動(dòng)態(tài)計(jì)算位置,所以滾動(dòng)事件觸發(fā)時(shí),CPU消耗很大
this.position[i]=[
{x:0,y:this.common.t},
{x:this.common.w-me.obj[i].obj.offsetWidth,y:this.common.t},
{x:0,y:(this.common.h+this.common.t-me.obj[i].obj.offsetHeight)/2+(this.common.t)/2},
{x:this.common.w-me.obj[i].obj.offsetWidth,y:(this.common.h+this.common.t-me.obj[i].obj.offsetHeight)/2+(this.common.t)/2},
{x:(this.common.w-me.obj[i].obj.offsetWidth)/2,y:(this.common.h+this.common.t-me.obj[i].obj.offsetHeight)/2+(this.common.t)/2},
{x:0,y:this.common.h+this.common.t-me.obj[i].obj.offsetHeight},
{x:this.common.w-me.obj[i].obj.offsetWidth,y:this.common.h+this.common.t-me.obj[i].obj.offsetHeight}
];
//處理自定義樣式
this.style="object"==typeof me.obj[i].style?{x:me.obj[i].style.left,y:me.obj[i].style.top+this.common.t}:{x:this.position[i][me.obj[i].style].x,y:this.position[i][me.obj[i].style].y};
//定位
me.obj[i].obj.style.left=this.style.x+"px";
me.obj[i].obj.style.top=this.style.y+"px";
}catch(e){
//功能是過濾無效obj
for(var j=i;j<me.obj.length-1;j++){
me.obj[j]=me.obj[j+1];
me.obj.length=me.obj.length-1;
}
}
}
};
//初始化
window.scroll(1,1);
};
AutoScroll.prototype.Add=function(){
var obj=arguments[0];
//獲得當(dāng)前position
var oldposition=$(obj.id).style.position;
$(obj.id).style.position="absolute";
//不使用fixed,雖然高版本瀏覽器都已經(jīng)支持fixed
this.obj.push({
obj:$(obj.id),
oldposition:oldposition,
style:obj.style
});
};
AutoScroll.prototype.Remove=function(){
var obj=arguments[0];
for(var i=0;i<this.obj.length;i++){
if(this.obj[i].obj==$(obj.id)){
//還原初始狀態(tài)position
this.obj[i].obj.style.position=this.obj[i].oldposition;
//是否真正移除
if(obj.remove){
this.obj[i].obj.innerHTML="";
document.body.removeChild(this.obj[i].obj);
}
//移除obj
for(var j=i;j<this.obj.length-1;j++){
this.obj[j]=this.obj[j+1];
}
this.obj.length=this.obj.length-1;
break;
}
}
};
var Scroller=new AutoScroll();