(#471) Add snapshot that draws beam centre crosshair

src/dodal/devices/areadetector/plugins/MJPG.py

@@ -1,9 +1,10 @@
 import threading
+from os.path import join as path_join
 from pathlib import Path
 
 import requests
 from ophyd import Component, Device, DeviceStatus, EpicsSignal, EpicsSignalRO, Signal
-from PIL import Image
+from PIL import Image, ImageDraw
 
 from dodal.devices.oav.oav_parameters import OAVConfigParams
 from dodal.log import LOGGER
@@ -57,3 +58,23 @@ def get_snapshot():
 
     def post_processing(self, image: Image.Image):
         pass
+
+
+class SnapshotWithBeamCentre(MJPG):
+    CROSSHAIR_LENGTH = 20
+
+    def post_processing(self, image: Image.Image):
+        assert self.oav_params is not None
+        beam_x = self.oav_params.beam_centre_i
+        beam_y = self.oav_params.beam_centre_j
+
+        draw = ImageDraw.Draw(image)
+        HALF_LEN = self.CROSSHAIR_LENGTH / 2
+        draw.line(((beam_x, beam_y - HALF_LEN), (beam_x, beam_y + HALF_LEN)))
+        draw.line(((beam_x - HALF_LEN, beam_y), (beam_x + HALF_LEN, beam_y)))
+
+        filename_str = self.filename.get()
+        directory_str = self.directory.get()
+
+        path = path_join(directory_str, f"{filename_str}_with_crosshair.png")
+        image.save(path)

src/dodal/devices/oav/oav_detector.py

@@ -15,6 +15,7 @@
     StatusBase,
 )
 
+from dodal.devices.areadetector.plugins.MJPG import SnapshotWithBeamCentre
 from dodal.devices.oav.grid_overlay import SnapshotWithGrid
 from dodal.devices.oav.oav_parameters import OAVConfigParams
 
@@ -78,12 +79,14 @@ class OAV(AreaDetector):
     tiff = ADC(OverlayPlugin, "-DI-OAV-01:TIFF:")
     hdf5 = ADC(HDF5Plugin, "-DI-OAV-01:HDF5:")
     grid_snapshot = Component(SnapshotWithGrid, "-DI-OAV-01:MJPG:")
+    snapshot = Component(SnapshotWithBeamCentre, "-DI-OAV-01:MJPG:")
     zoom_controller = Component(ZoomController, "-EA-OAV-01:FZOOM:")
 
     def __init__(self, *args, params: OAVConfigParams, **kwargs):
         super().__init__(*args, **kwargs)
         self.parameters = params
         self.grid_snapshot.oav_params = params
+        self.snapshot.oav_params = params
         self.subscription_id = None
         self._snapshot_trigger_subscription_id = None
 

tests/devices/unit_tests/areadetector/plugins/test_MJPG.py

@@ -0,0 +1,31 @@
+from unittest.mock import MagicMock, patch
+
+from ophyd.sim import instantiate_fake_device
+
+from dodal.devices.areadetector.plugins.MJPG import SnapshotWithBeamCentre
+from dodal.devices.oav.oav_detector import OAVConfigParams
+
+DISPLAY_CONFIGURATION = "tests/devices/unit_tests/test_display.configuration"
+ZOOM_LEVELS_XML = "tests/devices/unit_tests/test_jCameraManZoomLevels.xml"
+
+
+@patch("dodal.devices.areadetector.plugins.MJPG.Image")
+@patch("dodal.devices.areadetector.plugins.MJPG.ImageDraw")
+@patch("dodal.devices.areadetector.plugins.MJPG.requests")
+def test_given_snapshot_triggered_then_crosshair_drawn(
+    patch_requests, patch_image_draw, patch_image
+):
+    patch_line = MagicMock()
+    params = OAVConfigParams(ZOOM_LEVELS_XML, DISPLAY_CONFIGURATION)
+    params.update_on_zoom(1.0, 100, 100)
+
+    patch_image_draw.Draw.return_value.line = patch_line
+    snapshot: SnapshotWithBeamCentre = instantiate_fake_device(SnapshotWithBeamCentre)
+    snapshot.oav_params = params
+    snapshot.directory.set("/tmp/")
+    snapshot.filename.set("test")
+
+    status = snapshot.trigger()
+    status.wait()
+
+    assert len(patch_line.mock_calls) == 2

tests/devices/unit_tests/oav/test_oav.py

@@ -155,3 +155,8 @@ def test_calculate_beam_distance(h, v, expected_x, expected_y, oav: OAV):
         h,
         v,
     ) == (expected_x, expected_y)
+
+
+def test_when_oav_created_then_snapshot_parameters_set(oav: OAV):
+    assert oav.snapshot.oav_params is not None
+    assert oav.grid_snapshot.oav_params is not None