Making photo walls with javascript and problems that arise during the production process

Making photo walls with javascript and problems that arise during the production process_javascript skills

WBOY

Release： 2016-05-16 15:06:44

Original

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This article mainly makes a photo wall. The entire production process mainly needs to solve several problems:

1. How to perform layout conversion?

2. How to drag and drop pictures?

3. How to detect image collision problems? Perform collision detection

4. When multiple pictures collide, how to select the object with the smallest distance?

5. How to exchange the positions of two objects that collide with each other? Class libraries related to sports

The code is as follows:

<html>
<head>
<style>
body{background:black;margin: 0;padding: 0;color: white;font-size: 50px;}
p{position: absolute;width:20px;margin-left: 50px;}
#ul1{width: 690px;position: relative;margin: 20px auto;}
#ul1 li{list-style: none;float: left;margin: 10px;width: 200px;height: 150px;z-index: 1;border: 5px solid white;}
#ul1 .active{border: 5px solid yellow;}
</style>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
<script src="move2.js"></script>
<script type="text/javascript">
window.onload=function ()
{
  var oUl=document.getElementById('ul1');
  var oLi=oUl.getElementsByTagName('li');
  var sTore=[];
  var i;
  var iMinZindex=2;
  //进行布局转换
  for(i=0;i<oLi.length;i++)
  {
     sTore[i]={left:oLi[i].offsetLeft,top:oLi[i].offsetTop};//用数组存储每个li的左边距和高度

  }
  for(i=0;i<oLi.length;i++)
  {
     oLi[i].style.left=sTore[i].left+'px';
     oLi[i].style.top=sTore[i].top+'px';
     oLi[i].style.position='absolute';
     oLi[i].style.margin=0;
     oLi[i].index=i;
  }
  //图片拖拽处理
  for(i=0;i<oLi.length;i++)
  {
    setDrags(oLi[i]);
  }
  function setDrags(obj)
  {
    obj.onmousedown=function(ev)
    {
       //层级问题
      obj.style.zIndex=iMinZindex++;
      var oEvent=ev||event;
      var disx=oEvent.clientX-obj.offsetLeft;
      var disy=oEvent.clientY-obj.offsetTop;
      document.onmousemove=function(ev)
      {
        
        var oEvent=ev||event;
        obj.style.left=oEvent.clientX-disx+'px';//注意加px
        obj.style.top=oEvent.clientY-disy+'px';
        for(i=0;i<oLi.length;i++)
        {
          oLi[i].className='';
        }
        var oNear=findNearest(obj);
        if(oNear)//如果是最近的那个物体
        {
          oNear.className='active';
        }
      };
      document.onmouseup=function()
      {
         document.onmousemove=null;
         document.onmousedown=null;
         //交换两物体的位置
         var oNear=findNearest(obj);
         if(oNear)
         {
          startMove(oNear,sTore[obj.index]);
          startMove(obj,sTore[oNear.index]);
          //交换索引值
          var temp;
          temp=obj.index;
          obj.index=oNear.index;
          oNear.index=temp;

         }
         else
         {
          startMove(obj,sTore[obj.index])//回到自己的位置
         }
         return false;
      };
      clearInterval(obj.timer);
      return false;
    };
  }
//发生碰撞，使被碰的图片加边框,进行碰撞检测
function IBoundTest(obj1,obj2)
{
  var l1=obj1.offsetLeft;
  var r1=obj1.offsetLeft+obj1.offsetWidth;
  var t1=obj1.offsetTop;
  var b1=obj1.offsetTop+obj1.offsetHeight;
  
  var l2=obj2.offsetLeft;
  var r2=obj2.offsetLeft+obj2.offsetWidth;
  var t2=obj2.offsetTop;
  var b2=obj2.offsetTop+obj2.offsetHeight;
  if(r1<l2||l1>l2||b1<t2||t1>b2)//没有碰撞
  {
    return false;
  }
  else
  {
    return true;
  }

}
//得到两个物体之间的距离
function getDis(obj1,obj2)
{
  var a=obj1.offsetLeft-obj2.offsetLeft;
  var b=obj1.offsetTop-obj2.offsetTop;
  return Math.sqrt(a*a+b*b);
}
//发生碰撞，当与多个碰撞时，取其距离最小的图片
function findNearest(obj)
{
  var iMin=9999999;
  var iMindex=-1;
  var i;
  for(i=0;i<oLi.length;i++)
  {
     if(obj==oLi[i]){continue;}
     if(IBoundTest(obj,oLi[i]))//如果两个物体碰撞上
     {
        
         var dis=getDis(obj,oLi[i]);
         if(iMin>dis)
         {
           iMin=dis;
           iMindex=i;
         }
     }
  }
  if(iMindex==-1){return null;}
  else
  {
    return oLi[iMindex];//返回最近的那个
  }
}


  
}
</script>
</head>
<body >
<p>照片墙</p>
<ul id="ul1">
 <li><img src="images/1.jpg"></li>
 <li><img src="images/2.jpg"></li>
 <li><img src="images/3.jpg"></li>
 <li><img src="images/4.jpg"></li>
 <li><img src="images/5.jpg"></li>
 <li><img src="images/1.jpg"></li>
 <li><img src="images/2.jpg"></li>
 <li><img src="images/3.jpg"></li>
 <li><img src="images/4.jpg"></li>
</ul>
</body>
</html>

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