[Imagery] Add example imagery

Add a telemetry source for example imagery to support development
of a view for image telemetry, WTD-1170.

example/imagery/src/ImageTelemetryProvider.js

@@ -0,0 +1,115 @@
+/*****************************************************************************
+ * Open MCT Web, Copyright (c) 2014-2015, United States Government
+ * as represented by the Administrator of the National Aeronautics and Space
+ * Administration. All rights reserved.
+ *
+ * Open MCT Web is licensed under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ * Open MCT Web includes source code licensed under additional open source
+ * licenses. See the Open Source Licenses file (LICENSES.md) included with
+ * this source code distribution or the Licensing information page available
+ * at runtime from the About dialog for additional information.
+ *****************************************************************************/
+/*global define,Promise*/
+
+/**
+ * Module defining SinewaveTelemetryProvider. Created by vwoeltje on 11/12/14.
+ */
+define(
+    ["./ImageTelemetry"],
+    function (ImageTelemetry) {
+        "use strict";
+
+        /**
+         *
+         * @constructor
+         */
+        function ImageTelemetryProvider($q, $timeout) {
+            var subscriptions = [];
+
+            //
+            function matchesSource(request) {
+                return request.source === "imagery";
+            }
+
+            // Used internally; this will be repacked by doPackage
+            function generateData(request) {
+                return {
+                    key: request.key,
+                    telemetry: new ImageTelemetry()
+                };
+            }
+
+            //
+            function doPackage(results) {
+                var packaged = {};
+                results.forEach(function (result) {
+                    packaged[result.key] = result.telemetry;
+                });
+                // Format as expected (sources -> keys -> telemetry)
+                return { imagery: packaged };
+            }
+
+            function requestTelemetry(requests) {
+                return $timeout(function () {
+                    return doPackage(requests.filter(matchesSource).map(generateData));
+                }, 0);
+            }
+
+            function handleSubscriptions() {
+                subscriptions.forEach(function (subscription) {
+                    var requests = subscription.requests;
+                    subscription.callback(doPackage(
+                        requests.filter(matchesSource).map(generateData)
+                    ));
+                });
+            }
+
+            function startGenerating() {
+                $timeout(function () {
+                    handleSubscriptions();
+                    if (subscriptions.length > 0) {
+                        startGenerating();
+                    }
+                }, 1000);
+            }
+
+            function subscribe(callback, requests) {
+                var subscription = {
+                    callback: callback,
+                    requests: requests
+                };
+
+                function unsubscribe() {
+                    subscriptions = subscriptions.filter(function (s) {
+                        return s !== subscription;
+                    });
+                }
+
+                subscriptions.push(subscription);
+
+                if (subscriptions.length === 1) {
+                    startGenerating();
+                }
+
+                return unsubscribe;
+            }
+
+            return {
+                requestTelemetry: requestTelemetry,
+                subscribe: subscribe
+            };
+        }
+
+        return ImageTelemetryProvider;
+    }
+);