Merge branch 'picamera-rescue' into 'master'

Picamerax error recovery

See merge request openflexure/openflexure-microscope-server!86

openflexure_microscope/rescue/check_picamera.py

@@ -9,17 +9,36 @@ picamera_import_error = ErrorSource(
     )
 )
 
+picamera_errors = (
+    "Camera is not enabled. Try running 'sudo raspi-config' and ensure that the camera has been enabled.",
+)
+
+picamera_mmal_errors = {
+    "Failed to enable connection: Out of resources": "Camera already in use by another application."
+}
+
 
 def main():
     error_sources = []
     logging.info("Attempting to import picamera...")
 
     try:
-        from picamerax import PiCamera as _
+        import picamerax
     except Exception as e:  # pylint: disable=W0703
-        # TODO: Parse exception object for a few different issues, and append different error sources
-        # E.g. pi with camera already in use, disconnected, unsupported OS, etc
+        # TODO: Parse exception object for a few different issues, and append
+        # different error sources E.g. pi with camera already in use,
+        # disconnected, unsupported OS, etc
         logging.error(e)
         error_sources.append(picamera_import_error)
+    else:
+        try:
+            _ = picamerax.PiCamera()
+        except picamerax.PiCameraError as e:
+            if e.args[0] in picamera_errors:
+                error_sources.append(ErrorSource(e.args[0]))
+            elif e.args[0] in picamera_mmal_errors:
+                error_sources.append(ErrorSource(picamera_mmal_errors[e.args[0]]))
+            else:
+                error_sources.append(ErrorSource(e.args[0]))
 
     return error_sources