如何使用后置摄像头代替前置摄像头? [英] How to use back camera instead of the front camera?

问题描述

我有一个QR扫描摄像头，但是当我用手机打开网站时，面部摄像头会在我的网站上打开.我想使用后置摄像头.

I have a QR scanning camera, but when I open my website on a cell phone, the face camera turns on in my website. I want to use the back camera.

function setwebcam()
{

 var constraints = { audio: true, video: true };




document.getElementById("result").innerHTML="- scanning -";
if(stype==1)
{
    setTimeout(captureToCanvas, 500);    
    return;
}
var n=navigator;
document.getElementById("outdiv").innerHTML = vidhtml;
v=document.getElementById("v");

if(n.getUserMedia)
    n.getUserMedia(constraints, success, error);
else
if(n.webkitGetUserMedia)
{
    webkit=true;
    n.webkitGetUserMedia(constraints, success, error);
}
else
if(n.mozGetUserMedia)
{
    moz=true;
    n.mozGetUserMedia(constraints, success, error);
}

推荐答案

如果要强制设备使用前置摄像头，可以添加

If you want to force the device to use front camera you can add facingMode in constraints:

var constraints = { 
  audio: true,
  video: {
    facingMode: 'environment'
};

或使用exact:

facingMode: { exact: 'environment' }

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