<NME> trackable_finite_float.ts
<BEF> ADDFILE
<MSG> Feat: Trackable finite float

For tracking primitive sizes in vector graphics layers

<DFF> @@ -0,0 +1,29 @@
+/**
+ * @license
+ * Copyright 2016 Google Inc.
+ * 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.
+ */
+
+/**
+ * @file Convenience interface for creating TrackableValue instances designed to represent alpha
+ * (opacity) values.
+ */
+
+import {TrackableValue} from 'neuroglancer/trackable_value';
+import {verifyFiniteFloat} from 'neuroglancer/util/json';
+
+export type TrackableFiniteFloat = TrackableValue<number>;
+
+export function trackableFiniteFloat(initialValue = 1.0) {
+  return new TrackableValue<number>(initialValue, verifyFiniteFloat);
+}

Feat: Trackable finite float