[WIP] Improve Yolo WASM UI example (#591)

* return detections with classes names

* ignore .DS_Store

* example how to load wasm module

* add param to set model size

* add param for model size

* accept iou and confidence threshold on run

* conf and iou thresholds

* clamp only

* remove images from branch

* a couple of renamings, add readme with instructions

* final design

* minor font + border update

candle-wasm-examples/yolo/yoloWorker.js

@@ -0,0 +1,49 @@
+//load the candle yolo wasm module
+import init, { Model } from "./build/m.js";
+
+class Yolo {
+  static instance = {};
+  // Retrieve the YOLO model. When called for the first time,
+  // this will load the model and save it for future use.
+  static async getInstance(modelID, modelURL, modelSize) {
+    // load individual modelID only once
+    if (!this.instance[modelID]) {
+      await init();
+
+      self.postMessage({ status: `loading model ${modelID}:${modelSize}` });
+      const modelRes = await fetch(modelURL);
+      const yoloArrayBuffer = await modelRes.arrayBuffer();
+      const weightsArrayU8 = new Uint8Array(yoloArrayBuffer);
+      this.instance[modelID] = new Model(weightsArrayU8, modelSize);
+    } else {
+      self.postMessage({ status: "model already loaded" });
+    }
+    return this.instance[modelID];
+  }
+}
+
+self.addEventListener("message", async (event) => {
+  const { imageURL, modelID, modelURL, modelSize, confidence, iou_threshold } =
+    event.data;
+  try {
+    self.postMessage({ status: "detecting" });
+
+    const yolo = await Yolo.getInstance(modelID, modelURL, modelSize);
+
+    self.postMessage({ status: "loading image" });
+    const imgRes = await fetch(imageURL);
+    const imgData = await imgRes.arrayBuffer();
+    const imageArrayU8 = new Uint8Array(imgData);
+
+    self.postMessage({ status: `running inference ${modelID}:${modelSize}` });
+    const bboxes = yolo.run(imageArrayU8, confidence, iou_threshold);
+
+    // Send the output back to the main thread as JSON
+    self.postMessage({
+      status: "complete",
+      output: JSON.parse(bboxes),
+    });
+  } catch (e) {
+    self.postMessage({ error: e });
+  }
+});