[英]Force rear camera on mobile device?
嘗試將Instascan二維碼掃描儀連接到AR.js 。 一切正常,但是手機的前置攝像頭打開了,切換到后面就不行了。 庫分別與后置攝像頭配合使用並允許您進行切換,並且只有第一個打開。 Chrome瀏覽器不允許你在打開頁面時選擇攝像頭,所以問題是相關的,主要是針對他。
代碼示例: Codepen 、 MediaTrackSettings
<html>
<head>
<script src="https://rawgit.com/schmich/instascan-builds/master/instascan.min.js"></script>
<script src="https://aframe.io/releases/1.0.3/aframe.min.js"></script>
<script src="https://raw.githack.com/jeromeetienne/AR.js/2.2.2/aframe/build/aframe-ar.js"></script>
</head>
<body>
<a-scene>
<a-entity camera></a-entity>
</a-scene>
</body>
</html>
// Instascan QR scanner
let scanner = new Instascan.Scanner(
{
video: document.getElementById('arjs-video')
}
);
scanner.addListener('scan', function(content) {
alert('Content: ' + content);
window.open(content, "_blank");
});
// Instascan camera switch
Instascan.Camera.getCameras().then(function (cameras) {
if (cameras.length > 1) {
scanner.start(cameras[cameras.length - 1]);
} else {
scanner.start(cameras[0]);
}
}).catch(function (e) {
console.error(e);
});
// MediaTrackSettings
let supports = navigator.mediaDevices.getSupportedConstraints();
if (supports["facingMode"]) {
alert('Not Support!');
} else {
let constraints = {
facingMode: { exact: "environment" }
};
myTrack.applyConstraints(constraints);
這對我有用。 我在 Microsoft Surface 和 Android 手機上對此進行了測試。
//Detect user's cameras
Instascan.Camera.getCameras().then(function (cameras) {
//If a camera is detected
if (cameras.length > 0) {
//If the user has a rear/back camera
if (cameras[1]) {
//use that by default
scanner.start(cameras[1]);
} else {
//else use front camera
scanner.start(cameras[0]);
}
} else {
//if no cameras are detected give error
console.error('No cameras found.');
}
}).catch(function (e) {
console.error(e);
});
我沒有包括 MediaTrackSettings 並且沒有任何問題。
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