Preview: overlay erreur si DSLR deconnecte pendant la capture

- Overlay semi-transparent sur le preview quand camera_erreur recue
- Timeout 3s : si aucune frame recue, affiche l'erreur automatiquement
- Disparait des que les frames reprennent (camera_ok ou nouvelle frame)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/css/style.css

@@ -303,6 +303,39 @@ html, body {
   object-fit: contain;
 }
 
+.preview-erreur-camera {
+  position: absolute;
+  top: 0; left: 0; right: 0; bottom: 0;
+  background: rgba(0, 0, 0, 0.85);
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  gap: 1rem;
+  color: #fff;
+  z-index: 10;
+}
+
+.preview-erreur-camera.cache {
+  display: none;
+}
+
+.preview-erreur-icon {
+  font-size: 5rem;
+  animation: pulse-texte 1.5s ease-in-out infinite;
+}
+
+.preview-erreur-camera p {
+  font-size: 1.8rem;
+  font-weight: bold;
+  margin: 0;
+}
+
+.preview-erreur-camera span {
+  font-size: 1.2rem;
+  opacity: 0.7;
+}
+
 .compte-a-rebours {
   position: absolute;
   top: 0; left: 0;

frontend/index.html

@@ -63,6 +63,11 @@
     <section id="ecran-capture" class="ecran">
       <div id="preview-live" class="preview-live">
         <img id="img-preview" src="" alt="Preview">
+        <div id="preview-erreur-camera" class="preview-erreur-camera cache">
+          <div class="preview-erreur-icon">&#128247;</div>
+          <p>Appareil photo deconnecte</p>
+          <span>Reconnexion en cours...</span>
+        </div>
       </div>
       <div id="compte-a-rebours" class="compte-a-rebours cache">
         <span id="chiffre-car">3</span>

frontend/js/camera.js

@@ -2,18 +2,37 @@
 
 let previewActif = false;
 let previewInterval = null;
+let previewTimeoutId = null;
+const PREVIEW_TIMEOUT_MS = 3000;
 
 const EMOJI_CAR = { 3: '🤪', 2: '😱', 1: '🔥' };
 
 // --- Preview live ---
 
+function afficherErreurPreview(visible) {
+  const el = document.getElementById('preview-erreur-camera');
+  if (!el) return;
+  if (visible) el.classList.remove('cache');
+  else el.classList.add('cache');
+}
+
+function resetPreviewTimeout() {
+  if (previewTimeoutId) clearTimeout(previewTimeoutId);
+  previewTimeoutId = setTimeout(() => {
+    if (previewActif) afficherErreurPreview(true);
+  }, PREVIEW_TIMEOUT_MS);
+}
+
 function lancerPreview() {
   if (previewActif) return;
   previewActif = true;
+  afficherErreurPreview(false);
 
   previewInterval = setInterval(() => {
     if (previewActif) wsEnvoyer({ type: 'preview' });
   }, 100);
+
+  resetPreviewTimeout();
 }
 
 function arreterPreview() {
@@ -22,12 +41,28 @@ function arreterPreview() {
     clearInterval(previewInterval);
     previewInterval = null;
   }
+  if (previewTimeoutId) {
+    clearTimeout(previewTimeoutId);
+    previewTimeoutId = null;
+  }
+  afficherErreurPreview(false);
 }
 
 wsOnMessage('preview', (msg) => {
   if (!previewActif) return;
   const img = document.getElementById('img-preview');
   if (img) img.src = msg.image;
+  afficherErreurPreview(false);
+  resetPreviewTimeout();
+});
+
+// Erreur camera pendant la preview
+wsOnMessage('camera_erreur', () => {
+  if (previewActif) afficherErreurPreview(true);
+});
+
+wsOnMessage('camera_ok', () => {
+  afficherErreurPreview(false);
 });
 
 // --- Capture ---