前端通过 MediaDevices.getUserMedia()实现调用摄像头拍照保存MediaDevices.getU

MediaDevices.getUserMedia() 会提示用户给予使用媒体输入的许可，媒体输入会产生一个MediaStream，里面包含了请求的媒体类型的轨道。此流可以包含一个视频轨道（来自硬件或者虚拟视频源，比如相机、视频采集设备和屏幕共享服务等等）、一个音频轨道（同样来自硬件或虚拟音频源，比如麦克风、A/D转换器等等），也可能是其它轨道类型。

看一下我实现的效果图吧在这里插入图片描述

我是这样写的demo代码

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>摄像拍照</title>
</head>
<body>
  <video id="video" width="640" height="480" autoplay></video>
  <button id="snap">拍照</button>
  <button id="save">保存</button>
  <canvas id="canvas" width="640" height="480"></canvas>

  <script>
    // Grab elements, create settings, etc.
    var count=0;//是否点击过拍照
    var video = document.getElementById('video');
    
    // Get access to the camera!
    if(navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {
      // Not adding `{ audio: true }` since we only want video now
      navigator.mediaDevices.getUserMedia({ video: true }).then(function(stream) {
        //video.src = window.URL.createObjectURL(stream);
        video.srcObject = stream;
        video.play();
      });
    }

    // Elements for taking the snapshot
    var canvas = document.getElementById('canvas');
    var context = canvas.getContext('2d');
    var video = document.getElementById('video');
    // Trigger photo take
    var snap= document.getElementById("snap");

    snap.addEventListener("click", function() {
      context.drawImage(video, 0, 0, 640, 480);
      count++;
      if(video.paused){
        snap.innerText="拍照"
        video.play();
      }else{
        snap.innerText="重新拍一张呀"
        video.pause();
      }
    });
    var save=document.getElementById("save");
      save.addEventListener("click",function(){
    if(count===0){
      alert("请先拍一张帅气照")
    }else{
      var a = document.createElement('a');
     console.log(context.drawImage);
     a.setAttribute('href', canvas.toDataURL());　　//toDataUrl：将canvas画布信息转化为base64格式图片
     a.setAttribute('download', 'downImg')　　//这个是必须的，否则会报错
     a.setAttribute('target', '_self');
     a.click()
    }
    })
  </script>
</body>
</html>

其它

前置或者后置摄像头在移动设备（电话）上

var front = false;
document.getElementById('flip-button').onclick = function() { front = !front; };

var constraints = { video: { facingMode: (front? "user" : "environment") } };

更多使用看MDN