html5实现摇一摇功能

原理：使用DeviceMotion实现，关于DeviceMotion介绍可以查看


https://developer.mozilla.org/en-US/docs/Web/Reference/Events/devicemotion

通过DeviceMotionEvent，可以获得accelerationIncludingGravity的x,y,z属性，根据x,y,z属性的变化来判断设备是否有摇一摇的事件发生。

accelerationIncludeingGravity说明：

The acceleration of the device. This value includes the effect of gravity, and may be the only value available on devices that don’t have a gyroscope to allow them to properly remove gravity from the data.

代码如下：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <meta http-equiv="content-type" content="text/html;charset=utf-8">
  <title> html5使用DeviceMotionEvent实现摇一摇 </title>
  <style type="text/css">
  .center{position:absolute; width:640px; height:480px; left:50%; top:50%; margin-left:-320px; margin-top:-240px; line-height:480px; text-align:center; font-size:100px; }
  .normal{background:#000000;}
  .normal .txt{color:#FFFFFF;}
  .doing{background:#FF0000;}
  .doing .txt{color:#FFFF00;}
  </style>
 </head>

 <body id="mybody" class="normal">
    <div id="txt" class="txt center">请执行摇一摇</div>
 </body>

 <script type="text/javascript">
    var doing = 0;  // 判断是否在动画显示中
    var speed = 23; // 定义摇动的速度数值
    var lastx = 0;
    var lasty = 0;
    var lastz = 0;

    function handleMotionEvent(event) {
        var x = event.accelerationIncludingGravity.x;
        var y = event.accelerationIncludingGravity.y;
        var z = event.accelerationIncludingGravity.z;

        if(doing==0){
            if(Math.abs(x-lastx)>speed || Math.abs(y-lasty)>speed){
                doing = 1;
                show();
            }
        }

        lastx = x;
        lasty = y;
        lastz = z;
    }

    function show(){
        document.getElementById('mybody').className = 'doing';
        document.getElementById('txt').innerHTML = '执行了摇一摇';
        setTimeout(function(){
            doing=0;
            document.getElementById('mybody').className='normal';
            document.getElementById('txt').innerHTML = '请执行摇一摇';
        },3000);
    }

    window.addEventListener("devicemotion", handleMotionEvent, true);
 </script>

</html>