能夠感知滑鼠移動方位的遮罩層效果程式碼例項

admin發表於2017-04-15
遮罩

分享一段程式碼例項，它實現了感知滑鼠移動方位的遮罩層效果。

也就是是遮罩層的出現和滑鼠進入的方位是一致的。

程式碼例項如下:

[HTML] 純文字檢視 複製程式碼
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="author" content="http://www.softwhy.com/" />
<title>螞蟻部落</title>
<style>
* {
  margin: 0;
  padding: 0;
}
ul {
  width: 630px;
  overflow: hidden;
  margin: 100px auto;
}
li {
  float: left;
  width: 200px;
  height: 200px;
  background: #ccc;
  margin: 5px;
  position: relative;
  overflow: hidden;
}
li span {
  position: absolute;
  top: 0;
  left: 200px;
  width: 100%;
  height: 100%;
  background: rgba(255,0,0,0.3);
}
li span p {
  font-size: 14px;
  color: #fff;
  padding: 10px;
  white-space: pre-wrap;
}
</style>
<script>
function getStyle(obj, name) {
  if (obj.currentStyle) {
    return obj.currentStyle[name];
  } else {
    return getComputedStyle(obj, false)[name];
  }
}
 
function move(obj, json, options) {
  options = options || {};
  options.duration = options.duration || 700;
  options.easing = options.easing || 'ease-in';
 
  var count = Math.floor(options.duration / 30);
 
  var start = {};
  var dis = {};
 
  for (var name in json) {
 
    start[name] = parseFloat(getStyle(obj, name));
 
    dis[name] = json[name] - start[name];
 
  }
  var n = 0;
  clearInterval(obj.timer);
  obj.timer = setInterval(function() {
    n++;
 
    for (var name in json) {
 
      switch (options.easing) {
        case 'linear':
          var cur = start[name] + dis[name] * n / count;
          break;
        case 'ease-in':
          var a = Math.pow(n / count, 3);
          var cur = start[name] + dis[name] * a;
          break;
        case 'ease-out':
          var a = Math.pow(1 - n / count, 3);
          var cur = start[name] + dis[name] * (1 - a);
          break;
      }
 
      if (name == 'opacity') {
        obj.style[name] = cur;
        obj.style.filter = 'alpha(opacity:' + (cur * 100) + ')';
      } else {
        obj.style[name] = cur + 'px';
      }
 
    }
 
    if (n == count) {
      clearInterval(obj.timer);
 
      options.complete && options.complete();
    }
 
  }, 30);
}
 
function a2d(n) {
  return n * 180 / Math.PI;
}
 
function hoverDir(obj, ev) {
  var a = ev.clientX - (obj.offsetLeft + obj.offsetWidth / 2);
  var b = obj.offsetTop + obj.offsetHeight / 2 - ev.clientY;
  return Math.round((a2d(Math.atan2(b, a)) + 180) / 90) % 4;
 
}
 
function through(obj) {
  obj.onmouseenter = function(ev) {
    var oEvent = ev || event;
    var oS = this.children[0];
    var dir = hoverDir(obj, oEvent);
    switch (dir) {
      case 0:
        oS.style.left = '-200px';
        oS.style.top = 0;
        break;
      case 1:
        oS.style.left = 0;
        oS.style.top = '200px';
        break;
      case 2:
        oS.style.left = '200px';
        oS.style.top = 0;
        break;
      case 3:
        oS.style.left = 0;
        oS.style.top = '-200px';
        break;
    }
    move(oS, {
      left: 0,
      top: 0
    }, {
      duration: 300,
      easeing: 'linear'
    });
  }
  obj.onmouseleave = function(ev) {
    var oEvent = ev || event;
    var oS = this.children[0];
    var dir = hoverDir(obj, oEvent);
    switch (dir) {
      case 0:
        move(oS, {
          left: -200,
          top: 0
        }, {
          duration: 300,
          easing: 'linear'
        });
        break;
      case 1:
        move(oS, {
          left: 0,
          top: 200
        }, {
          duration: 300,
          easing: 'linear'
        });
        break;
      case 2:
        move(oS, {
          left: 200,
          top: 0
        }, {
          duration: 300,
          easing: 'linear'
        });
        break;
      case 3:
        move(oS, {
          left: 0,
          top: -200
        }, {
          duration: 300,
          easing: 'linear'
        });
        break;
    }
  };
}
window.onload = function() {
  var oLi = document.getElementsByTagName("li");
  for (var i = 0; i < oLi.length; i++) {
    through(oLi[i])
  }
}
</script>
</head>
<body>
  <ul>
    <li><span><p>螞蟻部落歡迎您</p></span></li>
    <li><span><p>螞蟻部落歡迎您</p></span></li>    
    <li><span><p>螞蟻部落歡迎您</p></span></li>    
    <li><span><p>螞蟻部落歡迎您</p></span></li>    
    <li><span><p>螞蟻部落歡迎您</p></span></li>    
    <li><span><p>螞蟻部落歡迎您</p></span></li>  
  </ul>
</body>
</html>

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