Fix race condition gphoto2 : lock non-bloquant preview cede la place a la 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._gp_lock = threading.Lock()  # Un seul appel gphoto2 a la fois
 
     def connecter(self, source=None) -> bool:
         """Connecte la camera. source: 'gphoto2', 'webcam:0', 'webcam:2', etc."""
@@ -147,21 +149,20 @@ class Camera:
 
         for attempt in range(3):
             try:
-                chemin_camera = self.camera.capture(gp.GP_CAPTURE_IMAGE)
-                fichier_camera = gp.CameraFile()
-                self.camera.file_get(
-                    chemin_camera.folder, chemin_camera.name, gp.GP_FILE_TYPE_NORMAL, fichier_camera
-                )
-                tmp_path = str(chemin_dest) + ".tmp"
-                fichier_camera.save(tmp_path)
-
+                with self._gp_lock:
+                    chemin_camera = self.camera.capture(gp.GP_CAPTURE_IMAGE)
+                    fichier_camera = gp.CameraFile()
+                    self.camera.file_get(
+                        chemin_camera.folder, chemin_camera.name, gp.GP_FILE_TYPE_NORMAL, fichier_camera
+                    )
+                    tmp_path = str(chemin_dest) + ".tmp"
+                    fichier_camera.save(tmp_path)
                 img = PILImage.open(tmp_path)
                 if img.width > 4000:
                     ratio = 4000 / img.width
                     img = img.resize((4000, int(img.height * ratio)), PILImage.LANCZOS)
                 img.save(str(chemin_dest), "JPEG", quality=92)
                 Path(tmp_path).unlink(missing_ok=True)
-
                 log.info(f"Photo capturee (DSLR) : {chemin_dest} ({img.width}x{img.height})")
                 return chemin_dest
             except gp.GPhoto2Error as e:
@@ -224,6 +225,8 @@ class Camera:
             log.warning(f"Viewfinder non supporté : {e}")
 
     def _preview_gphoto2(self) -> bytes | None:
+        if not self._gp_lock.acquire(blocking=False):
+            return None  # Capture en cours, on saute ce frame
         try:
             fichier = self.camera.capture_preview()
             donnees = bytes(fichier.get_data_and_size())
@@ -238,6 +241,8 @@ class Camera:
         except gp.GPhoto2Error as e:
             log.error(f"Erreur preview DSLR : {e}")
             return None
+        finally:
+            self._gp_lock.release()
 
     def _preview_webcam(self) -> bytes | None:
         if not self.webcam or not self.webcam.isOpened():