store frame metadata when reading a specific scene (#492)

Author: joshua-gould

aicsimageio/readers/nd2_reader.py

@@ -80,6 +80,10 @@ def _xarr_reformat(self, delayed: bool) -> xr.DataArray:
                 delayed=delayed, squeeze=False, position=self.current_scene_index
             )
             xarr.attrs[constants.METADATA_UNPROCESSED] = xarr.attrs.pop("metadata")
+            if self.current_scene_index is not None:
+                xarr.attrs[constants.METADATA_UNPROCESSED][
+                    "frame"
+                ] = rdr.frame_metadata(self.current_scene_index)
         return xarr.isel({nd2.AXIS.POSITION: 0})
 
     @property

aicsimageio/tests/readers/extra_readers/test_nd2_reader.py

@@ -227,3 +227,13 @@ def test_aicsimage(
         expected_physical_pixel_sizes=expected_physical_pixel_sizes,
         expected_metadata_type=expected_metadata_type,
     )
+
+
+def test_frame_metadata() -> None:
+    filename = "ND2_dims_rgb_t3p2c2z3x64y64.nd2"
+    uri = get_resource_full_path(filename, LOCAL)
+    rdr = ND2Reader(uri)
+    rdr.set_scene(0)
+    assert isinstance(
+        rdr.xarray_data.attrs["unprocessed"]["frame"], nd2.structures.FrameMetadata
+    )