From 4d458fafd70411e3826bf6c6b8257e24a54b34c9 Mon Sep 17 00:00:00 2001
From: Adam Soltys <adam@coinos.io>
Date: Fri, 14 Mar 2025 09:18:38 -0700
Subject: new scanner

---
 src/routes/(app)/scan/+page.svelte | 186 +++++++++++++++++++++++++++++++------
 1 file changed, 157 insertions(+), 29 deletions(-)

(limited to 'src')

diff --git a/src/routes/(app)/scan/+page.svelte b/src/routes/(app)/scan/+page.svelte
index edff522e..aab7bcaa 100644
--- a/src/routes/(app)/scan/+page.svelte
+++ b/src/routes/(app)/scan/+page.svelte
@@ -1,54 +1,182 @@
 <script>
-  import { tick } from "svelte";
-  import Icon from "$comp/Icon.svelte";
-  import QrScanner from "qr-scanner";
-  import { onMount, onDestroy } from "svelte";
   import { back } from "$lib/utils";
   import { goto } from "$app/navigation";
-
-  let scanner, vid = $state(), resizing;
+  import { onMount, onDestroy } from "svelte";
+  import { BarcodeDetector } from "barcode-detector/ponyfill";
 
   let resize = () => {
     if (resizing) clearTimeout(resizing);
     resizing = setTimeout(initialize, 1000);
   };
 
-  let initialize = async () => {
-    if (scanner) {
-      scanner.stop();
-      await new Promise((r) => setTimeout(r, 1000));
+  let videoEl;
+  let canvasEl;
+  let barcodeDetector;
+  let scanningFrameId;
+  let cameras = [];
+  let selectedCamera = "";
+  let detectionResult = null; // will hold the detected QR code value
+
+  // Enumerate available video input devices
+  async function getCameraDevices() {
+    try {
+      const devices = await navigator.mediaDevices.enumerateDevices();
+      cameras = devices.filter((device) => device.kind === "videoinput");
+      if (!selectedCamera && cameras.length > 0) {
+        // Prefer a rear-facing camera if available
+        const envCamera = cameras.find(
+          (camera) =>
+            camera.label.toLowerCase().includes("back") ||
+            camera.label.toLowerCase().includes("env"),
+        );
+        selectedCamera = envCamera ? envCamera.deviceId : cameras[0].deviceId;
+      }
+    } catch (err) {
+      console.error("Error enumerating devices:", err);
     }
+  }
 
-    let options = { highlightScanRegion: true, highlightCodeOutline: true };
-    let cb = ({ data }) =>
-      scanner.stop() || goto(`/send/${encodeURIComponent(data)}`);
-    scanner = new QrScanner(vid, cb, options);
-    await tick();
-    scanner.start();
-  };
+  // Start the camera stream for a given deviceId
+  async function startCamera(deviceId) {
+    stopCameraStream();
+    detectionResult = null; // reset detection on restart
+    try {
+      const constraints = deviceId
+        ? { video: { deviceId: { exact: deviceId } } }
+        : { video: { facingMode: "environment" } };
+      const stream = await navigator.mediaDevices.getUserMedia(constraints);
+      videoEl.srcObject = stream;
+      await videoEl.play();
+    } catch (err) {
+      console.error("Error accessing camera:", err);
+    }
+  }
+
+  // Stop any active video stream and cancel the scanning loop
+  function stopCameraStream() {
+    if (videoEl && videoEl.srcObject) {
+      const stream = videoEl.srcObject;
+      if (stream.getTracks) {
+        stream.getTracks().forEach((track) => track.stop());
+      }
+    }
+    if (scanningFrameId) {
+      cancelAnimationFrame(scanningFrameId);
+    }
+  }
+
+  function handleDetection(barcode) {
+    detectionResult = barcode.rawValue;
+    stopCameraStream();
+    goto(`/send/${encodeURIComponent(detectionResult)}`);
+  }
+
+  // The scanning loop: draw the video frame onto a hidden canvas and detect QR codes.
+  function scanLoop() {
+    if (!videoEl.videoWidth || !videoEl.videoHeight) {
+      scanningFrameId = requestAnimationFrame(scanLoop);
+      return;
+    }
+
+    const context = canvasEl.getContext("2d");
+    if (!context) return;
 
+    // Ensure canvas dimensions match the video
+    canvasEl.width = videoEl.videoWidth;
+    canvasEl.height = videoEl.videoHeight;
+    context.drawImage(videoEl, 0, 0, canvasEl.width, canvasEl.height);
+
+    barcodeDetector
+      .detect(canvasEl)
+      .then((barcodes) => {
+        if (barcodes.length > 0) {
+          handleDetection(barcodes[0]);
+          return; // Stop scanning on detection.
+        }
+      })
+      .catch((err) => {
+        console.error("Detection error:", err);
+      });
+
+    // Continue scanning if no detection has occurred.
+    if (!detectionResult) {
+      scanningFrameId = requestAnimationFrame(scanLoop);
+    }
+  }
+
+  // Handle change of camera selection
+  async function onCameraChange(event) {
+    selectedCamera = event.target.value;
+    await startCamera(selectedCamera);
+    videoEl.addEventListener("loadeddata", () => {
+      canvasEl.width = videoEl.videoWidth;
+      canvasEl.height = videoEl.videoHeight;
+      scanLoop();
+    });
+  }
+
+  // Provide a way to restart scanning
+  async function restart() {
+    detectionResult = null;
+    await startCamera(selectedCamera);
+    videoEl.addEventListener("loadeddata", () => {
+      canvasEl.width = videoEl.videoWidth;
+      canvasEl.height = videoEl.videoHeight;
+      scanLoop();
+    });
+  }
+
+  let initialize = async () => {
+    barcodeDetector = new BarcodeDetector({ formats: ["qr_code"] });
+    await getCameraDevices();
+    await startCamera(selectedCamera);
+    videoEl.addEventListener("loadeddata", () => {
+      canvasEl.width = videoEl.videoWidth;
+      canvasEl.height = videoEl.videoHeight;
+      scanLoop();
+    });
+  };
   onMount(initialize);
-  onDestroy(() => scanner?.stop());
+
+  onDestroy(() => {
+    stopCameraStream();
+  });
 </script>
 
 <svelte:window onresize={resize} />
-
 <div class="flex w-full mb-4 p-4">
-  <div class="mx-auto rounded-3xl">
-    <video
-      bind:this={vid}
-      class="border-4 rounded-3xl border-black max-h-[calc(100vh*0.7)]"
-></video>
+  <div class="mx-auto rounded-3xl space-y-5">
+      <video
+        bind:this={videoEl}
+        class="border-4 rounded-3xl border-black max-h-[calc(100vh*0.7)]"
+      ></video>
+      <canvas bind:this={canvasEl} style="display: none;"></canvas>
+      <div class="flex justify-center">
+        <button class="btn !w-auto" onclick={back}>Cancel</button>
+      </div>
+      <div>
+        <select
+          id="cameraSelect"
+          bind:value={selectedCamera}
+          onchange={onCameraChange}
+        >
+          {#each cameras as camera}
+            <option value={camera.deviceId}>
+              {camera.label || `Camera ${camera.deviceId}`}
+            </option>
+          {/each}
+        </select>
+      </div>
   </div>
 </div>
 
-<div class="flex justify-center">
-  <button class="btn !w-auto" onclick={back}>Cancel</button>
-</div>
-
 <style>
   video {
-    transition: transform 0.3s ease-out;
+    width: 100%;
+    max-width: 600px;
+    border: 4px solid black;
+    border-radius: 1rem;
     transform: scale(1);
+    transition: transform 0.3s ease-out;
   }
 </style>
-- 
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