Android webview实现拍照的方法

<div id="pnlVideo1">               <input type="hidden" name="imgNric1" id="imgNric1" />               <label id="nric" class="control-label labelfont" >Picture of Asset</label><br /><br />               <button id="btnOpen1" class="btn btn-default" type="button">Open WebCam</button>               <select id="videoSource" >    </select>               <div id="vdoOne" >                 <video id="video"  width="300" autoplay></video>                 <canvas id="canvasPreview"  width="300" height="224"></canvas>                 <canvas id="canvasUpload"  width='300' height='224'></canvas>                 <button id="snap" class="btn btn-default" type="button">Snap Photo</button>               </div>             </div>       <script type="text/javascript">     $(document).ready(function () {         });       //// 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 #######################     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);         }       }     }       function getStream() {       if (window.stream) {         window.stream.getTracks().forEach(function (track) {           track.stop();         });       }         var constraints = {                  video: {           optional: [{             sourceId: videoSelect.value           }]         }       };         navigator.mediaDevices.getUserMedia(constraints).         then(gotStream).catch(handleError);     }       function gotStream(stream) {       window.stream = stream; // make stream available to console       videoElement.class="lazy" data-srcObject = stream;     }       function handleError(error) {       console.log('Error: ', error);     }       //######################## End Video Source #################         // Get access to the camera!     if (navigator.mediaDevices && navigator.mediaDevices.getUserMedia) {       navigator.mediaDevices.getUserMedia({ video: true }).then(function (stream) {         videoElement.class="lazy" data-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,', '');       $("#imgNric1").val(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>