很久没怎么更新博客了,不想写,不想弄,懒了.
今天介绍一下Compass罗盘.
Compass
获得该设备的当前朝向.罗盘是一个检测设备方向或朝向的传感器,使用度作为衡量单位,取值范围从0度到359.99度。
这个对象有几个方法:
navigator.compass.getCurrentHeading(compassSuccess, compassError, compassOptions);
获取罗盘的当前朝向
compass.watchHeading
var watchID = navigator.compass.watchHeading(compassSuccess,
compassError, [compassOptions]);
在固定的时间间隔获取罗盘朝向的角度。
compass.clearWatch
navigator.compass.clearWatch(watchID);
停止watch ID参数指向的罗盘监视。
这个跟前面介绍的Accelerometer 加速器比较类似,就不详细解释了.
下面给段例子代码:
<!DOCTYPE html>
<html>
<head>
<title>Compass Example</title>
<script type="text/javascript" charset="utf-8" src="js/cordova-2.6.0.js"></script>
<script type="text/javascript" charset="utf-8">
var watchID = null;
// 等待Cordova加载
document.addEventListener("deviceready", onDeviceReady, false);
// Cordova加载完毕
function onDeviceReady() {
navigator.compass.getCurrentHeading(function(heading){
alert('Heading: ' + heading.magneticHeading);
}, function(compassError){
alert('Compass Error: ' + compassError.code);
});
startWatch();
}
// 开始监听Compass罗盘
function startWatch() {
// 每隔3秒 获取一次Compass数据
/**
* options选项
* frequency:多少毫秒获取一次罗盘朝向。(数字类型)(默认值:100)
* filter:能够触发watchHeadingFilter success回调的罗盘改变度数(数字类型)
* filter在某些设备上不支持具体参看文档
*/
var options = { frequency: 3000 };
watchID = navigator.compass.watchHeading(onSuccess, onError, options);
}
// 停止对Compass的监听
function stopWatch() {
if (watchID) {
navigator.compass.clearWatch(watchID);
watchID = null;
}
}
function onSuccess(heading) {
var element = document.getElementById('heading');
element.innerHTML = 'Heading: ' + heading.magneticHeading;
}
function onError(compassError) {
alert('Compass error: ' + compassError.code);
}
</script>
</head>
<body>
<div id="heading">Waiting for heading...</div>
<button onclick="startWatch();">Start Watching</button>
<button onclick="stopWatch();">Stop Watching</button>
</body>
</html>