javascript实现动态标签云

今天上学校的图书馆，看到了一个好玩的东西，特意百度了下，发现叫做“标签球”，效果图为：

直接代码如下：

CSS:

#div1 {position:relative; width:350px; height:350px; border:1px solid #000; margin: 20px auto 0; }
#div1 a {position:absolute; top:0px; left:0px; font-family: Microsoft YaHei; color:#000; font-weight:bold; text-decoration:none; padding: 3px 6px; }
#div1 a:hover {border: 1px solid #eee; background: #FFF; }
#div1 .blue {color:blue;}
#div1 .red {color:red;}
#div1 .green {color:green;}

HTML:

<div id="div1">
  <a href="#">标签云</a>
  <a href="#" class="red">PHP</a>
  <a href="#">瀑布流</a>
  <a href="#">Tab</a>
  <a href="#" class="blue">流体布局</a>
  <a href="#">SEO</a>
  <a href="#" class="red">彩蛋</a>
  <a href="#" class="green">JavaScript</a>
  <a href="#">miaov</a>
  <a href="#" class="red">CSS</a>
  <a href="#">asp.net</a>
  <a href="#" class="blue">蓝色经典</a>
  <a href="#">OOP</a>
  <a href="#" class="red">Android</a>
  <a href="#" class="blue">妙味茶馆</a>
  <a href="#">dialog</a>
  <a href="#" class="blue">淘客</a>
  <a href="#">Pin</a>
  <a href="#">微博</a>
  <a href="#" class="green">IPhone</a>
</div>

JS

 $(document).ready(function() {
  $("#div1").windstagball({
      radius:120,
      speed:10
    });
  });

首先得写好布局，最外层div样式position设置为relative

内层元素position为absolute，这样才能形成效果，top为0，left为0
先导入jquery文件，再导入相应的插件文件
获取$("#xxx")元素，并调用windstagball()函数，radius是标签球的变径大小，speed顾名思义就是运动的速度。

附上js插件

var radius = 120;
var dtr = Math.PI/180;
var d=300;

var mcList = [];
var active = false;
var lasta = 1;
var lastb = 1;
var distr = true;
var tspeed=10;
var size=250;

var mouseX=0;
var mouseY=0;

var howElliptical=1;

var aA=null;
var oDiv=null;

window.onload=function ()
{
    var i=0;
    var oTag=null;

    oDiv=document.getElementById('div1');

    aA=oDiv.getElementsByTagName('a');

    for(i=0;i<aA.length;i++)
    {
        oTag={};

        oTag.offsetWidth=aA[i].offsetWidth;
        oTag.offsetHeight=aA[i].offsetHeight;

        mcList.push(oTag);
    }

    sineCosine( 0,0,0 );

    positionAll();

    oDiv.onmouseover=function ()
    {
        active=true;
    };

    oDiv.onmouseout=function ()
    {
        active=false;
    };

    oDiv.onmousemove=function (ev)
    {
        var oEvent=window.event || ev;

        mouseX=oEvent.clientX-(oDiv.offsetLeft+oDiv.offsetWidth/2);
        mouseY=oEvent.clientY-(oDiv.offsetTop+oDiv.offsetHeight/2);

        mouseX/=5;
        mouseY/=5;
    };

    setInterval(update, 30);
};

function update()
{
    var a;
    var b;

    if(active)
    {
        a = (-Math.min( Math.max( -mouseY, -size ), size ) / radius ) * tspeed;
        b = (Math.min( Math.max( -mouseX, -size ), size ) / radius ) * tspeed;
    }
    else
    {
        a = lasta * 0.98;
        b = lastb * 0.98;
    }

    lasta=a;
    lastb=b;

    if(Math.abs(a)<=0.01 && Math.abs(b)<=0.01)
    {
        return;
    }

    var c=0;
    sineCosine(a,b,c);
    for(var j=0;j<mcList.length;j++)
    {
        var rx1=mcList[j].cx;
        var ry1=mcList[j].cy*ca+mcList[j].cz*(-sa);
        var rz1=mcList[j].cy*sa+mcList[j].cz*ca;

        var rx2=rx1*cb+rz1*sb;
        var ry2=ry1;
        var rz2=rx1*(-sb)+rz1*cb;

        var rx3=rx2*cc+ry2*(-sc);
        var ry3=rx2*sc+ry2*cc;
        var rz3=rz2;

        mcList[j].cx=rx3;
        mcList[j].cy=ry3;
        mcList[j].cz=rz3;

        per=d/(d+rz3);

        mcList[j].x=(howElliptical*rx3*per)-(howElliptical*2);
        mcList[j].y=ry3*per;
        mcList[j].scale=per;
        mcList[j].alpha=per;

        mcList[j].alpha=(mcList[j].alpha-0.6)*(10/6);
    }

    doPosition();
    depthSort();
}

function depthSort()
{
    var i=0;
    var aTmp=[];

    for(i=0;i<aA.length;i++)
    {
        aTmp.push(aA[i]);
    }

    aTmp.sort
    (
        function (vItem1, vItem2)
        {
            if(vItem1.cz>vItem2.cz)
            {
                return -1;
            }
            else if(vItem1.cz<vItem2.cz)
            {
                return 1;
            }
            else
            {
                return 0;
            }
        }
    );

    for(i=0;i<aTmp.length;i++)
    {
        aTmp[i].style.zIndex=i;
    }
}

function positionAll()
{
    var phi=0;
    var theta=0;
    var max=mcList.length;
    var i=0;

    var aTmp=[];
    var oFragment=document.createDocumentFragment();

    //随机排序
    for(i=0;i<aA.length;i++)
    {
        aTmp.push(aA[i]);
    }

    aTmp.sort
    (
        function ()
        {
            return Math.random()<0.5?1:-1;
        }
    );

    for(i=0;i<aTmp.length;i++)
    {
        oFragment.appendChild(aTmp[i]);
    }

    oDiv.appendChild(oFragment);

    for( var i=1; i<max+1; i++){
        if( distr )
        {
            phi = Math.acos(-1+(2*i-1)/max);
            theta = Math.sqrt(max*Math.PI)*phi;
        }
        else
        {
            phi = Math.random()*(Math.PI);
            theta = Math.random()*(2*Math.PI);
        }
        //坐标变换
        mcList[i-1].cx = radius * Math.cos(theta)*Math.sin(phi);
        mcList[i-1].cy = radius * Math.sin(theta)*Math.sin(phi);
        mcList[i-1].cz = radius * Math.cos(phi);

        aA[i-1].style.left=mcList[i-1].cx+oDiv.offsetWidth/2-mcList[i-1].offsetWidth/2+'px';
        aA[i-1].style.top=mcList[i-1].cy+oDiv.offsetHeight/2-mcList[i-1].offsetHeight/2+'px';
    }
}

function doPosition()
{
    var l=oDiv.offsetWidth/2;
    var t=oDiv.offsetHeight/2;
    for(var i=0;i<mcList.length;i++)
    {
        aA[i].style.left=mcList[i].cx+l-mcList[i].offsetWidth/2+'px';
        aA[i].style.top=mcList[i].cy+t-mcList[i].offsetHeight/2+'px';

        aA[i].style.fontSize=Math.ceil(12*mcList[i].scale/2)+8+'px';

        aA[i].style.filter="alpha(opacity="+100*mcList[i].alpha+")";
        aA[i].style.opacity=mcList[i].alpha;
    }
}

function sineCosine( a, b, c)
{
    sa = Math.sin(a * dtr);
    ca = Math.cos(a * dtr);
    sb = Math.sin(b * dtr);
    cb = Math.cos(b * dtr);
    sc = Math.sin(c * dtr);
    cc = Math.cos(c * dtr);
}