Update thorax model and improve model performance (#125)

Closes: #117

This bumps the thorax model from the yolo nano to the yolo sm (64 x 640 size) but greatly improves model performance by running a fake detection event on page load to get the model parameters in memory.

As a result of that change a new loading message was required so the f7 preloader was switched out for an f7 progress bar and more messaging was added during various stages.  The progress bar fixes the previous issue with the preloader.

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

Reviewed-on: #125

src/pages/detection-mixin.js

@@ -1,18 +1,22 @@
 import * as tf  from '@tensorflow/tfjs'
 import { f7 } from 'framework7-vue'
+import { nextTick } from 'vue'
 
 var model = null
 
 export default {
   methods: {
     async loadModel(weights) {
-      model = await tf.loadGraphModel(weights).then(graphModel => {
-        return graphModel
-      })
-  },
+      await nextTick()
+      model = await tf.loadGraphModel(weights)
+      const [modelWidth, modelHeight] = model.inputs[0].shape.slice(1, 3)
+      const dummyT = tf.ones([1,modelWidth,modelHeight,3])
+      model.predict(dummyT) //Run model once to preload weights for better response time
+      return model
+    },
     async localDetect(imageData) {
       console.time('pre-process')
-      const [modelWidth, modelHeight] = model.inputs[0].shape.slice(1, 3);
+      const [modelWidth, modelHeight] = model.inputs[0].shape.slice(1, 3)
       const input = tf.tidy(() => {
         return tf.image.resizeBilinear(tf.browser.fromPixels(imageData), [modelWidth, modelHeight]).div(255.0).expandDims(0)
       })