让HTML5支持后置摄像头

aperson

2016-12-22

让HTML5支持后置摄像头：

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>HTML5 GetUserMedia Demo</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0" />
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<input type="button" title="开启摄像头" value="开启摄像头" onclick="getMedia();" /><br />
<video height="120px" autoplay="autoplay"></video><hr />
<input type="button" title="拍照" value="拍照" onclick="getPhoto();" /><br />
<canvas id="canvas1" height="120px" ></canvas><hr />
<input type="button" title="视频" value="视频" onclick="getVedio();" /><br />
<canvas id="canvas2" height="120px"></canvas>

<script type="text/javascript">
    var video = document.querySelector('video');
    var audio, audioType;

    var canvas1 = document.getElementById('canvas1');
    var context1 = canvas1.getContext('2d');

    var canvas2 = document.getElementById('canvas2');
    var context2 = canvas2.getContext('2d');

    navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;
    window.URL = window.URL || window.webkitURL || window.mozURL || window.msURL;

    var exArray = []; //存储设备源ID
    MediaStreamTrack.getSources(function (sourceInfos) {
        for (var i = 0; i != sourceInfos.length; ++i) {
            var sourceInfo = sourceInfos[i];
            //这里会遍历audio,video，所以要加以区分
            if (sourceInfo.kind === 'video') {
                exArray.push(sourceInfo.id);
            }
        }
    });

    function getMedia() {
        if (navigator.getUserMedia) {
            navigator.getUserMedia({
                'video': {
                    'optional': [{
                        'sourceId': exArray[1] //0为前置摄像头，1为后置
                    }]
                },
                'audio':true
            }, successFunc, errorFunc);    //success是获取成功的回调函数
        }
        else {
            alert('Native device media streaming (getUserMedia) not supported in this browser.');
        }
    }

    function successFunc(stream) {
        //alert('Succeed to get media!');
        if (video.mozSrcObject !== undefined) {
            //Firefox中，video.mozSrcObject最初为null，而不是未定义的，我们可以靠这个来检测Firefox的支持
            video.mozSrcObject = stream;
        }
        else {
            video.src = window.URL && window.URL.createObjectURL(stream) || stream;
        }

        //video.play();

        // 音频
        audio = new Audio();
        audioType = getAudioType(audio);
        if (audioType) {
            audio.src = 'polaroid.' + audioType;
            audio.play();
        }
    }
    function errorFunc(e) {
        alert('Error！'+e);
    }


    // 将视频帧绘制到Canvas对象上,Canvas每60ms切换帧，形成肉眼视频效果
    function drawVideoAtCanvas(video,context) {
        window.setInterval(function () {
            context.drawImage(video, 0, 0,90,120);
        }, 60);
    }

    //获取音频格式
    function getAudioType(element) {
        if (element.canPlayType) {
            if (element.canPlayType('audio/mp4; codecs="mp4a.40.5"') !== '') {
                return ('aac');
            } else if (element.canPlayType('audio/ogg; codecs="vorbis"') !== '') {
                return ("ogg");
            }
        }
        return false;
    }

    // vedio播放时触发，绘制vedio帧图像到canvas
    //        video.addEventListener('play', function () {  
    //            drawVideoAtCanvas(video, context2);  
    //        }, false);  

    //拍照
    function getPhoto() {
        context1.drawImage(video, 0, 0,90,120); //将video对象内指定的区域捕捉绘制到画布上指定的区域，实现拍照。
    }

    //视频
    function getVedio() {
        drawVideoAtCanvas(video, context2);
    }

</script>
</body>
</html>

html5 var