[Fixed Position] Begin adding element proxy classes

Begin adding proxy classes to allow the toolbar to interact with
elements in a fixed position view, WTD-879.

platform/features/layout/src/elements/Accessor.js

@@ -0,0 +1,26 @@
+/*global define*/
+
+define(
+    [],
+    function () {
+        "use strict";
+
+        /**
+         * Utility function for creating getter-setter functions,
+         * since these are frequently useful for element proxies.
+         * @constructor
+         * @param {Object} object the object to get/set values upon
+         * @param {string} key the property to get/set
+         */
+        function Accessor(object, key) {
+            return function (value) {
+                if (arguments.length > 0) {
+                    object[key] = value;
+                }
+                return value;
+            };
+        }
+
+        return Accessor;
+    }
+);

platform/features/layout/src/elements/ElementProxies.js

@@ -0,0 +1,12 @@
+/*global define*/
+
+define(
+    ['./TelemetryProxy'],
+    function (TelemetryProxy) {
+        "use strict";
+
+        return {
+            "fixed.telemetry": TelemetryProxy
+        };
+    }
+);

platform/features/layout/src/elements/ElementProxy.js

@@ -0,0 +1,35 @@
+/*global define*/
+
+define(
+    ['./Accessor'],
+    function (Accessor) {
+        "use strict";
+
+        /**
+         * Abstract superclass for other classes which provide useful
+         * interfaces upon an elements in a fixed position view.
+         * This handles the generic operations (e.g. remove) so that
+         * subclasses only need to implement element-specific behaviors.
+         * @constructor
+         * @param element the telemetry element
+         * @param index the element's index within its array
+         * @param {Array} elements the full array of elements
+         */
+        function ElementProxy(element, index, elements) {
+            return {
+                x: new Accessor(element, 'x'),
+                y: new Accessor(element, 'y'),
+                z: new Accessor(element, 'z'),
+                width: new Accessor(element, 'width'),
+                height: new Accessor(element, 'height'),
+                remove: function () {
+                    if (elements[index] === element) {
+                        elements.splice(index, 1);
+                    }
+                }
+            };
+        }
+
+        return ElementProxy;
+    }
+);

platform/features/layout/src/elements/TelemetryProxy.js

@@ -0,0 +1,21 @@
+/*global define*/
+
+define(
+    ['./ElementProxy'],
+    function (ElementProxy) {
+        'use strict';
+
+        /**
+         *
+         */
+        function TelemetryProxy(element, index, elements) {
+            var proxy = new ElementProxy(element, index, elements);
+
+            proxy.id = element.id;
+
+            return proxy;
+        }
+
+        return TelemetryProxy;
+    }
+);