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How to achieve focus map effect using js

亚连

Jun 20, 2018 pm 05:44 PM

Native jsfocus map

The editor below will share with you an example of a simple focus map effect implemented in native js. It has a good reference value and I hope it will be helpful to everyone. Let’s follow the editor and take a look.

Use some packaged motion functions, mainly timers.

The effect is to automatically change pictures and picture descriptions at regular intervals.

<!DOCTYPE html>
<html>
 <head>
 <meta charset="UTF-8">
 <title></title>
 <style type="text/css">
  ul,
  li,
  p,
  h3 {
  padding: 0;
  margin: 0;
  list-style: none;
  }
  
  img {
  border: none;
  vertical-align: top;
  }
  
  #bg_box {
  width: 1000px;
  height: 590px;
  margin: 50px auto;
  position: relative;
  background: url(img/bg1.jpg) no-repeat;
  }
  
  .pic {
  width: 440px;
  height: 274px;
  position: absolute;
  top: 50px;
  left: 220px;
  overflow: hidden;
  }
  
  .li_box {
  width: 1760px;
  height: 274px;
  position: absolute;
  left: 0;
  }
  
  .tags {
  width: 440px;
  height: 80px;
  position: absolute;
  bottom: -80px;
  background-image: linear-gradient(0deg, rgba(0, 0, 0, 0.4) 0%, rgba(255, 255, 255, 0) 100%);
  color: white;
  padding-left: 20px;
  padding-top: 15px;
  box-sizing: border-box;
  }
  
  .tags:nth-of-type(1) {
  /*bottom: 0;*/
  }
  
  .img {
  float: left;
  width: 440px;
  height: 274px;
  }
  
  h3 {
  font: bold 20px/30px "微软雅黑";
  }
  
  p {
  font: 16px/30px "微软雅黑";
  }
 </style>
 <script src="tween.js"></script>
 <script src="commom.js"></script>
 <script type="text/javascript">
  window.onload = function() {
  //获取元素
  var liBbox = $(&#39;ul&#39;)[0];
  var li = $(&#39;li&#39;);
  var tags = $(&#39;.tags&#39;)
  var num = 0; //设置初始位置
  Change()
  function Change() {
   var M = tags[num];
   MTween(M, &#39;bottom&#39;, 0, 500, &#39;px&#39;, &#39;linear&#39;, function() { //先让描述内容出现
   num++
   if(num > li.length - 1) { //边界设置。
    return;
   }
   setTimeout(function() {
    MTween(M, &#39;bottom&#39;, -80, 500, &#39;px&#39;, &#39;linear&#39;, function() { //让描述内容不显示
    MTween(liBbox, &#39;left&#39;, -num * 440, 800, &#39;px&#39;, &#39;linear&#39;, function() {
     Change();
    }); //切换图片
    });
   }, 1000)
   });
  }
  }
 </script>
 </head>
 <body>
 <section id="bg_box">
  <p class="pic">
  <ul class="li_box">
   <li>
   <img  class="img lazy"  src="/static/imghwm/default1.png"  data-src="img/a5.gif"    alt="How to achieve focus map effect using js" >
   </li>
   <li>
   <img  class="img lazy"  src="/static/imghwm/default1.png"  data-src="img/a6.gif"    alt="How to achieve focus map effect using js" >
   </li>
   <li>
   <img  class="img lazy"  src="/static/imghwm/default1.png"  data-src="img/a7.gif"    alt="How to achieve focus map effect using js" >
   </li>
   <li>
   <img  class="img lazy"  src="/static/imghwm/default1.png"  data-src="img/a8.gif"    alt="How to achieve focus map effect using js" >
   </li>
  </ul>
  <p class="tags">
   <h3 id="下雨了">下雨了~~~</h3>
   <p class="tag">这是一个适合在家睡觉的日子!!</p>
  </p>
  <p class="tags">
   <h3 id="包饺子">包饺子~~~</h3>
   <p class="tag">一只会居家过日子的小狐狸！！</p>
  </p>
  <p class="tags">
   <h3 id="生气了">生气了~~~</h3>
   <p class="tag">吃掉好吃的就不生气了！！</p>
  </p>
  <p class="tags">
   <h3 id="出发了">出发了~~~</h3>
   <p class="tag">来一段说走就走的旅行!!</p>
  </p>
  </p>
 </section>
 </body>
</html>

commom.js

function MTween(obj,attr,end,duration,unit,way,callBack){
 if(obj.isAnim) return;
 //obj开始运动了 自定义属性
 obj.isAnim = true;
 if(!way){ //如果用户没有选择运动方式就默认匀速
 way = &#39;linear&#39;;
 }
 if(!unit){ //如果用户没有选择运动方式就默认匀速
 unit = &#39;&#39;;
 }
 var start = parseFloat(getStyle(obj,attr));//起始位置
// var end = 1000;//目标点
// var duration = 1000;//动画执行的总时间 单位是毫秒
 var startTime = Date.now();
 var s = end - start; //总路程
// var v = s/duration; //计算出来的速度
 //每次20ms走一帧
 clearInterval(timer);
 var timer = 0;
 timer = setInterval(function(){
 var endTime = Date.now();
 //计算出当前时间
 var t = endTime-startTime;
 if(t>=duration){
  t = duration;
  clearInterval(timer);//到达目标点要清除定时器
 }
//  obj.style[attr] = t*s/duration+start+&#39;px&#39;;
// console.log(Tween[way](t,start,s,duration))
 obj.style[attr] = Tween[way](t,start,s,duration)+unit;
 
  //透明度的兼容处理
  if(attr==&#39;opacity&#39;){
  obj.style.filter = &#39;Alpha(opacity=&#39;+Tween[way](t,start,s,duration)*100+&#39;)&#39;;
  }
 if(t==duration){
  obj.isAnim = false;
  //等到上一个动画完成 然后再调用
  if(callBack){
  callBack();
  }
 }
 },20);
}

tween.js

/*
* t : time 已过时间 当前时间-初始时间
* b : begin 起始值
* c : count 总的运动值 总路程
* d : duration 持续时间 总时间
*
* s = vt; => c = t*c/d 这里只计算总共要运动的路程 ，不包括起始位置
*
* attrVal = t*c/d + b;
*
* 曲线方程
*
* */
//Tween.linear();
var Tween = {
 linear: function (t, b, c, d){ //匀速
 return c*t/d + b;
 },
 easeIn: function(t, b, c, d){ //加速曲线
 return c*(t/=d)*t + b;
 },
 easeOut: function(t, b, c, d){ //减速曲线
 return -c *(t/=d)*(t-2) + b;
 },
 easeBoth: function(t, b, c, d){ //加速减速曲线
 if ((t/=d/2) < 1) {
  return c/2*t*t + b;
 }
 return -c/2 * ((--t)*(t-2) - 1) + b;
 },
 easeInStrong: function(t, b, c, d){ //加加速曲线
 return c*(t/=d)*t*t*t + b;
 },
 easeOutStrong: function(t, b, c, d){ //减减速曲线
 return -c * ((t=t/d-1)*t*t*t - 1) + b;
 },
 easeBothStrong: function(t, b, c, d){ //加加速减减速曲线
 if ((t/=d/2) < 1) {
  return c/2*t*t*t*t + b;
 }
 return -c/2 * ((t-=2)*t*t*t - 2) + b;
 },
 elasticIn: function(t, b, c, d, a, p){ //正弦衰减曲线（弹动渐入）
 if (t === 0) { 
  return b; 
 }
 if ( (t /= d) == 1 ) {
  return b+c; 
 }
 if (!p) {
  p=d*0.3; 
 }
 if (!a || a < Math.abs(c)) {
  a = c; 
  var s = p/4;
 } else {
  var s = p/(2*Math.PI) * Math.asin (c/a);
 }
 return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
 },
 elasticOut: function(t, b, c, d, a, p){ //*正弦增强曲线（弹动渐出）
 if (t === 0) {
  return b;
 }
 if ( (t /= d) == 1 ) {
  return b+c;
 }
 if (!p) {
  p=d*0.3;
 }
 if (!a || a < Math.abs(c)) {
  a = c;
  var s = p / 4;
 } else {
  var s = p/(2*Math.PI) * Math.asin (c/a);
 }
 return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;
 }, 
 elasticBoth: function(t, b, c, d, a, p){
 if (t === 0) {
  return b;
 }
 if ( (t /= d/2) == 2 ) {
  return b+c;
 }
 if (!p) {
  p = d*(0.3*1.5);
 }
 if ( !a || a < Math.abs(c) ) {
  a = c; 
  var s = p/4;
 }
 else {
  var s = p/(2*Math.PI) * Math.asin (c/a);
 }
 if (t < 1) {
  return - 0.5*(a*Math.pow(2,10*(t-=1)) * 
   Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
 }
 return a*Math.pow(2,-10*(t-=1)) * 
  Math.sin( (t*d-s)*(2*Math.PI)/p )*0.5 + c + b;
 },
 backIn: function(t, b, c, d, s){ //回退加速（回退渐入）
 if (typeof s == &#39;undefined&#39;) {
  s = 1.70158;
 }
 return c*(t/=d)*t*((s+1)*t - s) + b;
 },
 backOut: function(t, b, c, d, s){
 if (typeof s == &#39;undefined&#39;) {
  s = 3.70158; //回缩的距离
 }
 return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
 }, 
 backBoth: function(t, b, c, d, s){
 if (typeof s == &#39;undefined&#39;) {
  s = 1.70158; 
 }
 if ((t /= d/2 ) < 1) {
  return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;
 }
 return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;
 },
 bounceIn: function(t, b, c, d){ //弹球减振（弹球渐出）
 return c - Tween[&#39;bounceOut&#39;](d-t, 0, c, d) + b;
 }, 
 bounceOut: function(t, b, c, d){//*
 if ((t/=d) < (1/2.75)) {
  return c*(7.5625*t*t) + b;
 } else if (t < (2/2.75)) {
  return c*(7.5625*(t-=(1.5/2.75))*t + 0.75) + b;
 } else if (t < (2.5/2.75)) {
  return c*(7.5625*(t-=(2.25/2.75))*t + 0.9375) + b;
 }
 return c*(7.5625*(t-=(2.625/2.75))*t + 0.984375) + b;
 }, 
 bounceBoth: function(t, b, c, d){
 if (t < d/2) {
  return Tween[&#39;bounceIn&#39;](t*2, 0, c, d) * 0.5 + b;
 }
 return Tween[&#39;bounceOut&#39;](t*2-d, 0, c, d) * 0.5 + c*0.5 + b;
 }
}

The above is what I compiled for you. I hope it will be helpful to everyone in the future.

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