Javascript workers (#27)

* Share rhino_worker amongst demos

* Format rhino_worker

* Add pause/resume to rhino worker

demo/javascript/always-listening/.gitignore

@@ -7,3 +7,4 @@ pv_porcupine.wasm
 pv_rhino.js
 pv_rhino.wasm
 rhino.js
+rhino_worker.js

demo/javascript/always-listening/package.json

@@ -31,6 +31,10 @@
       "from": "../../../lib/wasm/pv_rhino.wasm",
       "to": "pv_rhino.wasm"
     },
+    {
+      "from": "../shared/rhino_worker.js",
+      "to": "rhino_worker.js"
+    },
     {
       "from": "../../../resources/porcupine/lib/wasm/pv_porcupine.js",
       "to": "pv_porcupine.js"

demo/javascript/shared/rhino_worker.js

@@ -0,0 +1,67 @@
+/*
+    Copyright 2018-2020 Picovoice Inc.
+    You may not use this file except in compliance with the license. A copy of the license is located in the "LICENSE"
+    file accompanying this source.
+    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.
+*/
+
+importScripts("pv_rhino.js");
+importScripts("rhino.js");
+
+onmessage = function (e) {
+  switch (e.data.command) {
+    case "init":
+      init(e.data.context);
+      break;
+    case "process":
+      process(e.data.inputFrame);
+      break;
+    case "pause":
+      paused = true;
+      break;
+    case "resume":
+      paused = false;
+      break;
+    case "release":
+      release();
+      break;
+  }
+};
+
+let context;
+let paused;
+let rhino = null;
+
+function init(context_) {
+  context = context_;
+  paused = false;
+
+  if (Rhino.isLoaded()) {
+    rhino = Rhino.create(context);
+  }
+}
+
+function process(inputFrame) {
+  if (rhino === null && Rhino.isLoaded()) {
+    rhino = Rhino.create(context);
+  }
+
+  if (!paused) {
+    if (rhino !== null) {
+      let result = rhino.process(inputFrame);
+      if ("isUnderstood" in result) {
+        postMessage(result);
+      }
+    }
+  }
+}
+
+function release() {
+  if (rhino != null) {
+    rhino.release();
+  }
+
+  rhino = null;
+}

demo/javascript/standalone/.gitignore

@@ -2,4 +2,5 @@ node_modules
 package-lock.json
 pv_rhino.js
 pv_rhino.wasm
-rhino.js
+rhino.js
+rhino_worker.js

demo/javascript/standalone/package.json

@@ -30,6 +30,10 @@
     {
       "from": "../../../lib/wasm/pv_rhino.wasm",
       "to": "pv_rhino.wasm"
+    },
+    {
+      "from": "../shared/rhino_worker.js",
+      "to": "rhino_worker.js"
     }
   ],
   "copyFilesSettings": {