add Camera.checkAlreadyCaptured

Author: Connormiha

lib/FileAPI.Camera.js

@@ -209,6 +209,45 @@
 callback('not_support_camera');
 };
 
+Camera.checkAlreadyCaptured = (function () {
+var enumerateDevices;
+
+if (navigator.mediaDevices && navigator.mediaDevices.enumerateDevices) {
+enumerateDevices = function (callback) {
+navigator.mediaDevices.enumerateDevices().then(callback);
+};
+} else if (!enumerateDevices && window.MediaStreamTrack && window.MediaStreamTrack.getSources) {
+enumerateDevices = window.MediaStreamTrack.getSources.bind(window.MediaStreamTrack);
+} else if (!enumerateDevices && navigator.enumerateDevices) {
+enumerateDevices = enumerateDevices.bind(navigator);
+}
+
+return function (callback) {
+var isFound;
+
+if (!enumerateDevices) {
+callback && callback(false);
+return;
+}
+
+enumerateDevices(function (devices) {
+var device;
+
+for (var i = 0; i < devices.length; i++) {
+device = devices[i];
+
+if ((device.kind === 'videoinput' || device.kind === 'video') && device.label) {
+isFound = true;
+callback && callback(true);
+break;
+}
+}
+});
+
+!isFound && callback && callback(false);
+};
+})();
+
 
 /**
  * @classFileAPI.Camera.Shot