html - 在网页中访问网络摄像头

Question

我正在开发一个网络应用程序。

在我的 guest 注册页面中，我需要访问网络摄像头来为 guest 拍照。

我拍摄的图像可以存储在指定位置。

这将是执行此操作的最佳方式。

欢迎使用java、JSP、html、java脚本或任何其他方法。

Answer 1

回答自己的问题，因为有更好的方法可以使用 HTML5。

方式一，从系统中获取默认摄像头

HTML

Video Tag
<br/>
<div class="camera">
    <video id="video">Video stream not available.</video>
    <button id="startbutton">Take photo</button>
</div>
<br/>
Canvas
<br/>
<canvas id="canvas"></canvas>

脚本

var width = 320;
var height = 0;
var streaming = false;

navigator.mediaDevices.getUserMedia({video: true, audio: false})
        .then(function (stream) {
            video.srcObject = stream;
            video.play();
        })
        .catch(function (err) {
            console.log("An error occured! " + err);
        });

video.addEventListener('canplay', function (ev) {
    if (!streaming) {
        height = video.videoHeight / (video.videoWidth / width);
        video.setAttribute('width', width);
        video.setAttribute('height', height);
        canvas.setAttribute('width', width);
        canvas.setAttribute('height', height);

        streaming = true;
    }
}, false);

startbutton.addEventListener('click', function (ev) {
    takepicture();
    ev.preventDefault();
}, false);

clearphoto();

function clearphoto() {
    var context = canvas.getContext('2d');
    context.fillStyle = "#AAA";
    context.fillRect(0, 0, canvas.width, canvas.height);
}

function takepicture() {
    var context = canvas.getContext('2d');
    if (width && height) {
        canvas.width = width;
        canvas.height = height;
        context.drawImage(video, 0, 0, width, height);

        var dataURL = canvas.toDataURL("image/jpeg", 0.95);
        if (dataURL && dataURL != "data:,") {
            var fileName = generateImageName();
            uploadimage(dataURL, fileName);
        } else {
            alert("Image not available");
        }
    } else {
        clearphoto();
    }
}

function generateImageName() {
    ... generate image name logic here ...
    return imageName;
}

function uploadimage(dataurl, filename) {
    ... upload logic here ...
}

屏幕截图

选项2，提供系统中可用摄像头的列表，让用户选择摄像头。

HTML

<select id="videoSelect"></select>
    <button id="startCameraButton">Start Camera</button>
    <br/>
    Video Tag
    <br/>
    <div class="camera">
        <video id="video">Video stream not available.</video>
        <button id="takePictureButton">Take photo</button>
    </div>
    <br/>
    Canvas
    <br/>
    <canvas id="canvas">
    </canvas>

脚本

var width = 320;
var height = 0;
var streaming = false;
var localstream = null;

startCameraButton.onclick = start;
takePictureButton.onclick = takepicture;

navigator.mediaDevices.enumerateDevices()
        .then(gotDevices)
        .catch(function (err) {
            console.log("An error occured while getting device list! " + err);
        });

function gotDevices(deviceInfos) {
    while (videoSelect.firstChild) {
        videoSelect.removeChild(videoSelect.firstChild);
    }

    for (var i = 0; i !== deviceInfos.length; ++i) {
        var deviceInfo = deviceInfos[i];
        var option = document.createElement('option');
        option.value = deviceInfo.deviceId;
        if (deviceInfo.kind === 'videoinput') {
            option.text = deviceInfo.label || 'Camera ' + (videoSelect.length + 1);
            videoSelect.appendChild(option);
        }
    }
}

function start() {
    stopVideo();
    clearphoto();
    var videoSource = videoSelect.value;
    var constraints = {
        audio: false,
        video: {deviceId: videoSource ? {exact: videoSource} : undefined}
    };
    navigator.mediaDevices.getUserMedia(constraints).
            then(gotStream).then(gotDevices).catch(handleError);
}



function gotStream(stream) {
    localstream = stream;
    video.srcObject = stream;
    video.play();
    // Refresh button list in case labels have become available
    return navigator.mediaDevices.enumerateDevices();
}

function handleError(error) {
    console.log('navigator.getUserMedia error: ', error);
}

video.addEventListener('canplay', function (ev) {
    if (!streaming) {
        height = video.videoHeight / (video.videoWidth / width);
        video.setAttribute('width', width);
        video.setAttribute('height', height);
        canvas.setAttribute('width', width);
        canvas.setAttribute('height', height);

        streaming = true;
    }
}, false);

clearphoto();

function clearphoto() {
    var context = canvas.getContext('2d');
    context.fillStyle = "#AAA";
    context.fillRect(0, 0, canvas.width, canvas.height);
}

function takepicture() {
    var context = canvas.getContext('2d');
    if (width && height) {
        canvas.width = width;
        canvas.height = height;
        context.drawImage(video, 0, 0, width, height);

        var dataURL = canvas.toDataURL("image/jpeg", 0.95);
        if (dataURL && dataURL != "data:,") {
            var fileName = generateImageName();
            fileName = fileName + ".txt"
            uploadimage(dataURL, fileName);
        } else {
            console.log("Image not available");
        }
    } else {
        clearphoto();
    }
}

    function generateImageName() {
    ... generate image name logic here ...
    return imageName;
}

function uploadimage(dataurl, filename) {
    ... upload logic here ...
}

function stopVideo() {
    if (localstream) {
        localstream.getTracks().forEach(function (track) {
            track.stop();
            localstream = null;
        });
    }
}

屏幕截图

选项3，让用户选择音视频源和音频输出

在选项 2 中，用户可以选择任何特定的相机。最重要的是，如果用户还想选择音频源和音频输出源，请修改上面的代码并进行以下更改。

HTML

            audioInputSelect
            <br/>
            <select id="audioInputSelect"></select>
            <br/>
            audioOutputSelect
            <select id="audioOutputSelect"></select>

脚本

function gotDevices(deviceInfos) {
    while (videoSelect.firstChild) {
        videoSelect.removeChild(videoSelect.firstChild);
    }

    for (var i = 0; i !== deviceInfos.length; ++i) {
        var deviceInfo = deviceInfos[i];
        var option = document.createElement('option');
        option.value = deviceInfo.deviceId;
        if (deviceInfo.kind === 'audioinput') {
            option.text = deviceInfo.label || 'Microphone ' + (audioInputSelect.length + 1);
            audioInputSelect.appendChild(option);
        } else if (deviceInfo.kind === 'audiooutput') {
            option.text = deviceInfo.label || 'Speaker ' + (audioOutputSelect.length + 1);
            audioOutputSelect.appendChild(option);
        } else if (deviceInfo.kind === 'videoinput') {
            option.text = deviceInfo.label || 'Camera ' + (videoSelect.length + 1);
            videoSelect.appendChild(option);
        }
    }
}

function start() {
    stopVideo();
    clearphoto();
    var audioSource = audioInputSelect.value;
    var videoSource = videoSelect.value;
    var constraints = {
      audio: {deviceId: audioSource ? {exact: audioSource} : undefined},
        video: {deviceId: videoSource ? {exact: videoSource} : undefined}
    };
    navigator.mediaDevices.getUserMedia(constraints).
            then(gotStream).then(gotDevices).catch(handleError);
}