Improvements to properties and docstrings

src/openflexure_microscope_server/things/autofocus.py

@@ -265,7 +265,7 @@ class JPEGSharpnessMonitor:
         stage: BaseStage,
         camera: BaseCamera,
         method: SharpnessMethod = SharpnessMethod.JPEG,
-        record: Optional[SharpnessMethod] = None,
+        record: Optional[int] = None,
     ) -> None:
         """Initialise a new JPEGSharpnessMonitor. The args are injected automatically.
 
@@ -355,7 +355,7 @@ class JPEGSharpnessMonitor:
 
             # FocusFoM metric
             if self.record & SharpnessMethod.FOCUS_FOM:
-                self._focus_foms.append(self.camera._focus_fom)
+                self._focus_foms.append(self.camera.focus_fom)
 
             if not self.running:
                 break
@@ -487,7 +487,7 @@ class AutofocusThing(lt.Thing):
         dz: int = 2000,
         start: Literal["centre", "base"] = "centre",
         sharpness_metric: SharpnessMethod = SharpnessMethod.JPEG,
-        record: Optional[SharpnessMethod] = None,
+        record: Optional[int] = None,
     ) -> SharpnessDataArrays:
         """Sweep the stage up and down, then move to the sharpest point.
 
@@ -499,10 +499,11 @@ class AutofocusThing(lt.Thing):
         :param start: Starting position of the sweep. "centre" begins at -dz/2,
             while "base" begins from the current position.
         :param sharpness_metric: Sharpness metric used for evaluation. Either
-            JPEG file size (JPEG) or inbuilt figure of metric (FOCUS_FOM).
+            JPEG file size (1) or inbuilt figure of metric (2).
         :param record: Optional bitmask of sharpness metrics to record during
-            acquisition. If None, defaults to recording only the selected
-            sharpness_metric.
+            acquisition. Sharpness metrics can be selected as the sum of their int
+            value (see sharpness_metric).
+            If None, defaults to recording only the selected sharpness_metric.
 
         :returns: SharpnessDataArrays containing all recorded sharpness and
             stage position data for the sweep.
@@ -561,7 +562,7 @@ class AutofocusThing(lt.Thing):
         dz: int = 2000,
         start: Literal["centre", "base"] = "centre",
         sharpness_metric: SharpnessMethod = SharpnessMethod.JPEG,
-        record: Optional[SharpnessMethod] = None,
+        record: Optional[int] = None,
     ) -> tuple[list[float], list[float]]:
         """Repeatedly autofocus the stage until it looks focused.
 
@@ -574,10 +575,11 @@ class AutofocusThing(lt.Thing):
         :param start: Starting position of the sweep. "centre" begins at -dz/2,
             while "base" begins from the current position.
         :param sharpness_metric: Sharpness metric used for evaluation. Either
-            JPEG file size (JPEG) or inbuilt figure of metric (FOCUS_FOM).
+            JPEG file size (1) or inbuilt figure of metric (2).
         :param record: Optional bitmask of sharpness metrics to record during
-            acquisition. If None, defaults to recording only the selected
-            sharpness_metric.
+            acquisition. Sharpness metrics can be selected as the sum of their int
+            value (see sharpness_metric).
+            If None, defaults to recording only the selected sharpness_metric.
 
         :returns: SharpnessDataArrays containing all recorded sharpness and
             stage position data for the sweep.

src/openflexure_microscope_server/things/camera/__init__.py

@@ -179,6 +179,7 @@ class BaseCamera(OFMThing):
     mjpeg_stream = lt.outputs.MJPEGStreamDescriptor()
     lores_mjpeg_stream = lt.outputs.MJPEGStreamDescriptor()
     _memory_buffer = CameraMemoryBuffer()
+    supports_focus_fom: bool = False
 
     def __init__(self, thing_server_interface: lt.ThingServerInterface) -> None:
         """Initialise the base camera, this creates the background detectors.
@@ -213,6 +214,17 @@ class BaseCamera(OFMThing):
         """Close hardware connection when the Thing context manager is closed."""
         pass
 
+    @property
+    def focus_fom(self) -> int:
+        """Return the focus figure of merit.
+
+        This returns a NotImplementedError if not supported by the camera.
+        To use, requires self.supports_focus_fom to be set to True.
+        """
+        raise NotImplementedError(
+            "This camera does not support Figure of Merit focusing."
+        )
+
     @lt.property
     def calibration_required(self) -> bool:
         """Whether the camera needs calibrating.

src/openflexure_microscope_server/things/camera/picamera.py

@@ -380,6 +380,11 @@ class StreamingPiCamera2(BaseCamera):
                         f"but found {hw_sensor_model}."
                     )
 
+    @property
+    def focus_fom(self) -> int:
+        """Return the focus figure of merit."""
+        return self._focus_fom
+
     def _on_frame_complete(self, request: Request) -> None:
         md = request.get_metadata()
         fom = md.get("FocusFoM")