javascript椭圆旋转相册实现代码_图象特效

init:function(id,options){ 
var defaultOptions={ 
width:600, //容器宽 
height:200, //容器高 
imgWidth:100, //图片宽 
imgHeight:60, //图片高 
maxScale:1.5, //最大缩放倍数 
minScale:0.5, //最小缩放倍数 
rotateSpeed:10 //运转速度 
} 
options=util.extend(defaultOptions,options);//参数设置 
this.container=util.$(id); 
this.width=options.width; 
this.height=options.height; 
imgWidth=this.imgWidth=options.imgWidth; 
imgHeight=this.imgHeight=options.imgHeight; 
this.maxScale=options.maxScale; 
this.minScale=options.minScale; 
scaleMargin=this.maxScale-this.minScale; 
this.rotateSpeed=options.rotateSpeed; 
this.imgs=util.$$('img',this.container); 
this.setContainerSize(this.width,this.height); 
initImgRC(this.imgs); 
}

/* 设置容器尺寸 */ 
setContainerSize:function(width,height){ 
width=width||this.width; 
height=height||this.height; 
this.container.style.position='relative'; 
this.container.style.width=width+'px'; 
this.container.style.height=height+'px'; 
changeRotateWH.call(this,width,height);//改变容器尺寸后改变旋转轨迹 
},

/* 改变椭圆旋转轨迹的横半轴长，竖半轴长*/ 
var changeRotateWH=function(width,height){ 
var halfScale=(this.maxScale-this.minScale)/2;//旋转到中间位置时的图片的缩放大小 
rotate={}; 
rotate.originX=width/2;//旋转原点X轴坐标 
rotate.originY=height/2;//旋转原点Y轴坐标 
rotate.halfRotateWidth=(width-this.imgWidth)/2; //旋转横半轴长 
rotate.halfRotateHeight=(height-this.imgHeight)/2; //旋转竖半轴长 
}

/* 设置图片旋转角和初始位置，大小 */ 
var initImgRC=function(imgs){ 
var len=imgs.length; 
con=(2*Math.PI)/len; 
for(var i=0;i<len;i++){ 
imgs[i].RC=i*con; 
imgs[i].style.width=imgWidth+'px'; 
imgs[i].style.height=imgHeight+'px'; 
setImgPositionAndSize(imgs[i],0); 
} 
}

/* 设置图片位置和大小的匀速变化 */ 
var setImgPositionAndSize=function(img,path,direction){ 
direction=direction||'CW'; 
var dir=direction=='CW'?-1:1; 
img.RC+=(path*dir); 
modifyImgAngle(img); 
setImgSize(img); 
}

/* 修改图片旋转角度（保证在0-2pai之间） */ 
var modifyImgAngle=function(img){ 
(img.RC>(2*Math.PI))&&(img.RC-=2*Math.PI); 
(img.RC<0)&&(img.RC+=2*Math.PI); 
}

/* 设置图片大小和位置 */ 
var setImgSize=function(img){ 
var left=rotate.originX+rotate.halfRotateWidth*Math.cos(img.RC)-imgWidth/2; 
var top=rotate.originY-rotate.halfRotateHeight*Math.sin(img.RC)-imgHeight/2; 
var scale=minScale+scaleMargin*(rotate.halfRotateHeight-rotate.halfRotateHeight*Math.sin(img.RC))/(2*rotate.halfRotateHeight);//图片在该时刻的缩放比 
img.style.cssText='position:absolute;left:'+left+'px;' 
+'top:'+top+'px;' 
+'width:'+imgWidth*scale+'px;' 
+'height:'+imgHeight*scale+'px;' 
+'z-index:'+Math.round(scale*100); 
}

/* 设置旋转模式（自动/手动）*/ 
setPattern:function(patternName,option){ 
option=option||{}; 
this.pattern=patternName; 
var rotateSpeed=option.rotateSpeed||10; 
this.path=Math.PI/1000*rotateSpeed; 
(typeof timeId!='undefined')&&window.clearInterval(timeId); 
if(patternName==='auto'){//自动模式 可传入旋转方向：option.rotateDir 旋转速度：option.rotateSpeed 
var self=this; 
var direction=option.rotateDir||'CW';//顺时针：CW 逆时针：ACW 
removeImgsHandler(this.imgs); 
timeId=window.setInterval(function(){ 
for(var i=0,len=self.imgs.length;i<len;i++){ 
setImgPositionAndSize(self.imgs[i],self.path,direction); 
} 
},20); 
} 
else if(patternName==='hand'){//手动模式，可传回调函数：option.onSelected 缓动模式：option.tween 
var onSelected=option.onSelected||util.emptyFunction; 
var tween=Tween[tween]||Tween['easeOut'];//缓动模式默认为easeout 
removeImgsHandler(this.imgs); 
(typeof timeId!='undefined')&&window.clearInterval(timeId); 
timeId=undefined; 
bindHandlerForImgs(this.imgs,this.path,tween,onSelected); 
} 
} 
}

var Tween = {//缓动类 默认提供三种缓动模式：linear easein easeout 
linear: function(t,b,c,d,dir){ return c*t/d*dir + b; }, 
easeIn: function(t,b,c,d,dir){ 
return c*(t/=d)*t*dir + b; 
}, 
easeOut: function(t,b,c,d,dir){ 
return -c *(t/=d)*(t-2)*dir + b; 
} 
};