Switch shared worker to basic service worker (#191)

Shared workers seem to cause problems with iOS (and sharing wasn't really required anyway), so this PR changes the shared workers to non-shared workers.  As a benefit, it preloads the full model and video models simultaneously which iproves performance when starting the video and running post video detection.

Signed-off-by: Justin Georgi <justin.georgi@gmail.com>

Reviewed-on: #191

src/assets/detect-worker.js

@@ -1,45 +1,39 @@
 import * as tf  from '@tensorflow/tfjs'
-import { f7 } from 'framework7-vue'
 
 let model = null
 
-self.onconnect = (e) => {
-  const port = e.ports[0];
-
-  port.onmessage = function (e) {
-    switch (e.data.call) {
-      case 'loadModel':
-        loadModel('.' + e.data.weights,e.data.preload).then(() => {
-          port.postMessage({success: 'model'})
-        }).catch((err) => {
-          port.postMessage({error: true, message: err.message})
-        })
-        break
-      case 'localDetect':
-        localDetect(e.data.image).then((dets) => {
-          port.postMessage({success: 'detection', detections: dets})
-        }).catch((err) => {
-          port.postMessage({error: true, message: err.message})
-        })
-        e.data.image.close()
-        break
-      case 'videoFrame':
-        videoFrame(e.data.image).then((frameDet) =>{
-          port.postMessage({succes: 'frame', coords: frameDet.cds, modelWidth: frameDet.mW, modelHeight: frameDet.mH})
-        }).catch((err) => {
-          port.postMessage({error: true, message: err.message})
-        })
-        e.data.image.close()
-        break
-      default:
-        console.log('Worker message incoming:')
-        console.log(e)
-        port.postMessage({result1: 'First result', result2: 'Second result'})
-        break
-    }
+onmessage = function (e) {
+  switch (e.data.call) {
+    case 'loadModel':
+      loadModel('.' + e.data.weights,e.data.preload).then(() => {
+        postMessage({success: 'model'})
+      }).catch((err) => {
+        postMessage({error: true, message: err.message})
+      })
+      break
+    case 'localDetect':
+      localDetect(e.data.image).then((dets) => {
+        postMessage({success: 'detection', detections: dets})
+      }).catch((err) => {
+        //throw (err)
+        postMessage({error: true, message: err.message})
+      })
+      e.data.image.close()
+      break
+    case 'videoFrame':
+      videoFrame(e.data.image).then((frameDet) =>{
+        postMessage({succes: 'frame', coords: frameDet.cds, modelWidth: frameDet.mW, modelHeight: frameDet.mH})
+      }).catch((err) => {
+        postMessage({error: true, message: err.message})
+      })
+      e.data.image.close()
+      break
+    default:
+      console.log('Worker message incoming:')
+      console.log(e)
+      postMessage({result1: 'First result', result2: 'Second result'})
+      break
   }
-
-  port.start()
 }
 
 async function loadModel(weights, preload) {