feat: restore QR code detection overlay in custom QrScanner

src/components/tools/QrScanner.vue

@@ -19,6 +19,99 @@ let stream = null
 let scanRafId = null
 let barcodeDetector = null
 
+const overlayCanvas = ref(null)
+
+const paintDetections = (codes) => {
+  const canvas = overlayCanvas.value
+  const video = videoRef.value
+
+  if (!canvas || !video) return
+
+  const ctx = canvas.getContext('2d')
+  const { width, height } = canvas.getBoundingClientRect()
+
+  // Update canvas size if needed (to match CSS size)
+  if (canvas.width !== width || canvas.height !== height) {
+    canvas.width = width
+    canvas.height = height
+  }
+
+  ctx.clearRect(0, 0, width, height)
+
+  if (!codes || codes.length === 0) return
+
+  const vw = video.videoWidth
+  const vh = video.videoHeight
+  if (!vw || !vh) return
+
+  // Calculate object-fit: cover scaling
+  const videoRatio = vw / vh
+  const canvasRatio = width / height
+
+  let drawWidth, drawHeight, startX, startY
+
+  if (canvasRatio > videoRatio) {
+    // Canvas is wider than video (video cropped top/bottom)
+    drawWidth = width
+    drawHeight = width / videoRatio
+    startX = 0
+    startY = (height - drawHeight) / 2
+  } else {
+    // Canvas is taller than video (video cropped left/right)
+    drawHeight = height
+    drawWidth = height * videoRatio
+    startY = 0
+    startX = (width - drawWidth) / 2
+  }
+
+  const scale = drawWidth / vw
+  const isMirrored = isFront.value
+
+  // Styles
+  const styles = getComputedStyle(document.documentElement)
+  const accent = styles.getPropertyValue('--primary-accent').trim() || '#00f2fe'
+
+  ctx.lineWidth = 4
+  ctx.strokeStyle = accent
+  ctx.fillStyle = accent
+
+  codes.forEach(code => {
+    const points = code.cornerPoints
+    if (!points || points.length < 4) return
+
+    ctx.beginPath()
+
+    const transform = (p) => {
+      let x = p.x * scale + startX
+      let y = p.y * scale + startY
+
+      if (isMirrored) {
+        x = width - x
+      }
+      return { x, y }
+    }
+
+    const p0 = transform(points[0])
+    ctx.moveTo(p0.x, p0.y)
+
+    for (let i = 1; i < points.length; i++) {
+      const p = transform(points[i])
+      ctx.lineTo(p.x, p.y)
+    }
+
+    ctx.closePath()
+    ctx.stroke()
+
+    // Draw corners
+    points.forEach(p => {
+      const tp = transform(p)
+      ctx.beginPath()
+      ctx.arc(tp.x, tp.y, 4, 0, Math.PI * 2)
+      ctx.fill()
+    })
+  })
+}
+
 const updateVideoAspect = () => {
   if (videoRef.value && videoRef.value.videoWidth && videoRef.value.videoHeight) {
     videoAspect.value = videoRef.value.videoWidth / videoRef.value.videoHeight
@@ -142,6 +235,7 @@ const detectLoop = async () => {
 
   try {
     const codes = await barcodeDetector.detect(videoRef.value)
+    paintDetections(codes)
     if (codes.length > 0) {
       onDetect(codes)
     }
@@ -384,6 +478,8 @@ const isUrl = (string) => {
               muted
             ></video>
 
+            <canvas ref="overlayCanvas" class="scan-overlay-canvas"></canvas>
+
             <div v-if="error" class="error-overlay">
               <p>{{ error }}</p>
               <button @click="startScan" class="retry-btn">Retry</button>
@@ -540,6 +636,16 @@ const isUrl = (string) => {
   transform: scaleX(-1);
 }
 
+.scan-overlay-canvas {
+  position: absolute;
+  top: 0;
+  left: 0;
+  width: 100%;
+  height: 100%;
+  pointer-events: none;
+  z-index: 5;
+}
+
 /* front mirror canvas removed */
 
 .error-overlay {