详解HTML5 使用video标签实现选择摄像头功能

1. html

// jquery reference // <script src="http://ajax.googleapis.com/ajax/libs/jquery/2.0.2/jquery.min.js"></script> // <input type="hidden" /> <button type="button" >Open WebCam</button> <select ></select> <div> <video autoplay></video> <canvas></canvas> <canvas></canvas> <button type="button">Snap Photo</button> </div>

2. javascript

<script> //// Elements for taking the snapshot var canvasPreview = document.getElementById('canvasPreview'); var canvasUpload = document.getElementById('canvasUpload'); var contextPreview = canvasPreview.getContext('2d'); var contextUpload = canvasUpload.getContext('2d'); //#################### Video Source #######################3 var videoElement = document.querySelector('video'); var videoSelect = document.querySelector('select#videoSource'); navigator.mediaDevices.enumerateDevices() .then(gotDevices).then(getStream).catch(handleError); videoSelect.onchange = getStream; function gotDevices(deviceInfos) { 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); } else { console.log('Found ome other kind of source/device: ', deviceInfo); } } } var _streamCopy = null; function getStream() { if (_streamCopy != null) { try { _streamCopy.stop(); // if this method doesn't exist, the catch will be executed. } catch (e) { _streamCopy.getVideoTracks()[0].stop(); // then stop the first video track of the stream } } var constraints = { audio:false, video: { optional: [ { sourceId: videoSelect.value } ] } }; navigator.mediaDevices.getUserMedia(constraints).then(gotStream).catch(handleError); } function gotStream(stream) { _streamCopy = stream; // make stream available to console videoElement.srcObject = stream; } function handleError(error) { alert(error.name + ": " + error.message); } //######################## End Video Source ################# // Get access to the camera! if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) { navigator.mediaDevices.getUserMedia({ video: true }).then(function(stream) { videoElement.src = window.URL.createObjectURL(stream); videoElement.play(); }); } else { document.getElementById("pnlVideo1").style.display = "none"; } //// Trigger photo take document.getElementById("snap").addEventListener("click", function() { contextPreview.drawImage(videoElement, 0, 0, 300, 224); contextUpload.drawImage(videoElement, 0, 0, 300, 224); document.getElementById("video").style.display = "none"; document.getElementById("snap").style.display = "none"; document.getElementById("canvasPreview").style.display = "block"; var image = document.getElementById("canvasUpload").toDataURL("image/jpeg"); image = image.replace('data:image/jpeg;base64,', ''); $("#imgValue").val(image); alert("image value :" + image); }); //// Trigger photo take document.getElementById("btnOpen1").addEventListener("click", function() { document.getElementById("vdoOne").style.display = "block"; document.getElementById("video").style.display = "block"; document.getElementById("snap").style.display = "block"; document.getElementById("canvasPreview").style.display = "none"; }); </script>

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