Fix race condition gphoto2 : verrou camera sur preview et capture

backend/camera.py

@@ -1,6 +1,7 @@
 import io
 import logging
 import subprocess
+import threading
 import time
 from datetime import datetime
 
@@ -66,6 +67,7 @@ class Camera:
         self.webcam = None
         self.webcam_index = -1
         self.preview_dslr_ok = True  # True si le dernier preview DSLR a reussi
+        self._lock = threading.Lock()  # Verrou pour eviter acces gphoto2 concurrent
 
     def connecter(self, source=None) -> bool:
         """Connecte la camera. source: 'gphoto2', 'webcam:0', 'webcam:2', etc."""
@@ -145,6 +147,7 @@ class Camera:
     def _capture_gphoto2(self, chemin_dest: Path) -> Path | None:
         from PIL import Image as PILImage
 
+        with self._lock:
             for attempt in range(3):
                 try:
                     chemin_camera = self.camera.capture(gp.GP_CAPTURE_IMAGE)
@@ -152,11 +155,9 @@ class Camera:
                     self.camera.file_get(
                         chemin_camera.folder, chemin_camera.name, gp.GP_FILE_TYPE_NORMAL, fichier_camera
                     )
-                # Sauvegarder le fichier brut temporairement
                     tmp_path = str(chemin_dest) + ".tmp"
                     fichier_camera.save(tmp_path)
 
-                # Redimensionner (max 4000px de large, JPEG 92%)
                     img = PILImage.open(tmp_path)
                     if img.width > 4000:
                         ratio = 4000 / img.width
@@ -203,6 +204,7 @@ class Camera:
         """Active le LiveView sur les Canon (nécessaire avant capture_preview)."""
         if self.mode != "gphoto2" or not self.connectee:
             return
+        with self._lock:
             try:
                 cfg = self.camera.get_config()
                 vf = cfg.get_child_by_name("viewfinder")
@@ -216,6 +218,7 @@ class Camera:
         """Désactive le LiveView."""
         if self.mode != "gphoto2" or not self.connectee:
             return
+        with self._lock:
             try:
                 cfg = self.camera.get_config()
                 vf = cfg.get_child_by_name("viewfinder")
@@ -226,14 +229,11 @@ class Camera:
                 log.warning(f"Viewfinder non supporté : {e}")
 
     def _preview_gphoto2(self) -> bytes | None:
+        with self._lock:
             try:
                 fichier = self.camera.capture_preview()
                 donnees = bytes(fichier.get_data_and_size())
-            # Redimensionner pour alléger le WebSocket
-            img = cv2.imdecode(
-                np.frombuffer(donnees, dtype=np.uint8),
-                cv2.IMREAD_COLOR,
-            )
+                img = cv2.imdecode(np.frombuffer(donnees, dtype=np.uint8), cv2.IMREAD_COLOR)
                 if img is not None:
                     h, w = img.shape[:2]
                     if w > 960: