一(yī)、Compass 介紹方法參數δ€₹(shù)
&nb™∞ ↑sp; Compass 也(yě)就(jiù)是(↔€shì)，常說(shuō)的(de)指南(nán)針，又(yòu)叫羅盤
×; 方法
×→>; c<∑×ompass.getCurrentHeading
&nb&↕₩sp; comΩ<α€pass.watchHeading
&nb★→ sp; cσ★ ompass.clearWatch
ε ↕; &nbλ Ωαsp; compass.watchHeadingFil× ter (obsolete)
&nbs™∏p; &§ε βnbsp; compass.clearWat∏붮chFilter (obsolete)
↕•δ 參數(shù)
&n•♦bsp; &∞φ ¥nbsp; compassSuccess
δ←; compassErr©☆"₹or
&n'≥≥bsp; compasα≥ ↔sOptions
✔ε♠; compassHeading
二、compass.getCurrentHeading ✔≥• &n✔↕≈bsp; &nb↕ sp; 對(duì)象
改對(duì)象主要(yào)獲取羅盤的(de)當☆↔±前朝向。
navigator.compass.getCurrentHeading(cπ•σompassSuccess, compassError, comp ♣ §assOptions);
compassSuccess 成功的(de)回調函數(♦₹×shù)
compassError 失敗的(de)回調函數(shù)
compassOptions 獲取指南(nán )針信息時(shí)的(de)一(yī)個(gè)選項例如(rú)：頻(pín♥$¶)率，它一(yī)般為(wèi)一(yī)個(gè)₹♦json &nbs♦≠£₹p; &±™$nbsp; ✔®¶; &nb'↓sp; φ₩↓; &₹✔γnbsp; 對(duì)象在
（compass.watchHeading ）中↓×用(yòng)
function onSuccess(heading) {
alert('Headin☆≤Ωg: ' + heading.magneticHeading);
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};
function onError(error) {
alert('Compass↓©✘∑Error: ' error.code);
};
navigator.compass.getCur ↔Ω♦rentHeading(onSuccess, onErr™₽¥or);
回調成功後會(huì)用(yòng)到(dàoφγ±↕)compassHeading 對(duì)象
magneti•↓λ↓cHeading：羅盤在某一(yī)時(shí)刻的(de)朝向，'♣取值範圍是(shì)0 - 359.99 度。(數(sh♠÷ù)字類型)
t'∞φ§rueHeading ：羅盤在某一(yī)時(shí)刻相(xià ←≥×ng)對(duì)于北(běi)極的(de)朝向，取值範✘☆圍是(shì)0 - 359.99 度。如(rú)果是(shì)負φε
值則表明(míng)該參數(shù)不(bù)确定。 ±(數(shù)字類型)
£≈↕₹; headingAccuracy：實際度數(shù)γ≈φ↔和(hé)記錄度數(shù)之間(jiān)的(de)偏差。(數(shù)∏★§♣字類型)
"timestamp：确定羅盤朝向的(de)時(εσshí)刻.。(毫秒(miǎo)數(shù)®$π↑)
簡單列子(zǐ)：
<!DOCTYPE html>
<html>
<head>
<title>Compass Example&l§∑t;/title>
<script type="text/javas εcript" charset="u✔•tf-8" src="•σphonegap.js"></script>
<script type="text/javascr÷★ipt" charset="utf-8&q ↑uot;>
&n£ bsp; // 等待加載PhoneGap
docume±φ™→nt.addEventListener("devi™λ&ceready", onDeviceReady,σ☆ ↔ false);
// PhoneG→¶ε→ap 加載完畢
function onD"±<eviceReady() {
&nbs&p; " ; navigator.compass.ge>↔tCurrentHeading(onSuccess, onError);
&nbs₹β♣p; }
// onS≥↑₽uccess: 返回當 ÷前的(de)朝向數(shù)據
&nbs←€Ωp; function onSuccess(heading)∏₹₩ {
™© ale×♥¥rt('Heading: ' + heading.magn↓γ←£eticHeading);
&nbs'λ♠♥p; }
// onError:&nλbsp; 返回朝向數(shù)據失敗
function onE₹♥rror(compassError) {
$; &n↕σbsp; alert('Compass∞± Error: ' + compassError.code);
}
</script>
</head>
<body>
<h←∑ 1>Example</h1&♦₽gt;
<p>get'CurrentHeading</p>
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</body>
</html>
三、compass.watchHeading 對(duì" )象
說(shuō)明(míng)：
羅盤是(shì)一(yī)個(gè)檢測設備方向或朝向的(de)傳∏"感器(qì)，使用(yòng)度作(zuò)↕♣為(wèi)衡量單位，取值範圍從(cóng)0 度到(dào)359.99 φ÷度。
compass.watchHeading 每隔固定時(s±±hí)間(jiān)就(jiù)獲取一(y&☆→ī)次設備的(de)當前朝向。每次取得(de)朝向後，headingSucc$↕πess 回調函
數(shù)會(huì)被執行(xíng)。通(tōng)過com★ε×<passOptions 對(duì)象的(de)frequency 參數(s λhù)可(kě)以設定以毫秒(miǎo)為(wèi)單位的>₽"÷(de)時(shí)間(jiān)間(jεδiān)隔。
返回的(de)watch ID 是(sh™&↑ì)羅盤監視(shì)周期的(de)引用(yòng)，可(kě)以通(↓↔♣₽tōng)過compass.clearWatch ©"調用(yòng)該watch ≤ ↓ ID 以停止對(duì)羅盤的(de♣≈∑)監
視(shì)。
var watchID = naviga"σ> tor.compass.watchHeading(compassSucσ♥¥cess,
γ¥ &nbs ♥ 'p; &nbs±♥∞≤p; &£ nbsp; &nb≤ ✘sp; compassError, [compassOptio ×ns]);
var options = {
frequen≥δ→£cy: 3000
};
var watchID = navigator.comφπ★←pass.watchHeading(onSucc §ess, onError, options);
通(tōng)過clearWatch 來(lái)停止對(duì ☆)羅盤的(de)檢測
watchID：由compass.watchHeading ✔©β返回的(de)引用(yòng)标示。
navigator.compass.clα♥λearWatch(watchID);
<!DOCTYPE html>>★δ♣;
<html>
<head>
<title>Compass Exampl↓→>e</title>
<script type="text/jε₹✘♦avascript" charset=≠≤"utf-8" src="phδ ®♠onegap.js"></script>
<script type="≠®;text/javascript" ¥πφ; charset="utf-8& ÷×quot;>
// watchID 是(sλ hì)當前“watchHeading &r&∞dquo;的(de)引用(yòng)
var₽ watchID = null;
// 等>σ待加載PhoneGap
&n♠¥"bsp; document.addEventListener('§"deviceready&quo>''t;, onDeviceReady, false);
&nγ₽bsp; // PhoneGap 加載完畢
↔→ε function onDeviceRead£Ω±y() {
&n'<σbsp; startWatch(¥ Ω);
€; }
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//&nbβ↕×sp; 開(kāi)始監視(shì)羅盤
functioλ n startWatch() {
&nbs&δ p; '←; // 每隔3"≤₽ 秒(miǎo)鐘(zhōng)更新一(yī)次羅盤數(✘✘shù)據
&nbs ←±$p; &nπ×bsp; var opti ♠ons = { frequency: 3000 }↔®;
& €§nbsp; ↓¶ watchID✔γ✘ = navigator.compass.watch✔★Heading(onSuccess, on±>Error, options);
}
&nbs$εp; // 停止監視(shì)羅盤
&nb≠☆↓sp; function s↓topWatch() {
&∑Ω•nbsp; &nb₽•←≥sp; if (watchID) {
✘α &nbs♠≥p; ←♣↕ navigator.co ✔mpass.clearWatch(watchID);
&">✘"nbsp; $$; ¶₩; watchID = nul₩>♠l;
&n™"bsp; }→•★>
}$↓
¶"♦ // onSuccess: ®↑ ® 返回羅盤的(de)當前朝向
&nbs<✔÷p; function onSuccess(♥>heading) {
&n≈'bsp; & ↕→nbsp; var element = document.getElem¶< entById('heading');
&nb★λsp; ♠♣£> element.i∏÷nnerHTML = 'Heading: ' + heading.magne←♦ticHeading;
<☆£}
♠₩&→ // onError: 獲取羅♥'盤朝向失敗
&"≥α₩nbsp; function onError(compassError)↕ {
★<©λ; &nb✔✔sp; alert('Com±•±pass error: ' + compassError.cod₽÷e);
}
</script>
</head>
<body>
< <div id="heading&quoε↔t;>Waiting for heading.>≈♥..</div>
&n✔ ₩♠bsp; <button"startWa£δtch();">Start Watching< φβ ;/button>
<but&ε☆$ton"stopWatch();">St↔&op Watching</button>
</body>
</html>
