Create basic gallery class that finds Things that want to show data

src/openflexure_microscope_server/things/gallery.py

@@ -0,0 +1,31 @@
+"""Server-side gallery functionality.
+
+The types of data that are captured and how they display in the gallery are defined by
+the Things that capture the Data. This thing just provides a unified way for the gallery
+front end to access the data.
+"""
+
+from typing import Mapping, Optional
+
+import labthings_fastapi as lt
+
+from openflexure_microscope_server.things import OFMThing
+
+
+class GalleryThing(lt.Thing):
+    """A Thing for communicating with the front end gallery."""
+
+    all_ofm_things: Mapping[str, OFMThing] = lt.thing_slot()
+
+    _gallery_providing_things: Optional[Mapping[str, OFMThing]] = None
+
+    @property
+    def gallery_providing_things(self) -> Mapping[str, OFMThing]:
+        """All Things that provide data to the gallery."""
+        if self._gallery_providing_things is None:
+            self._gallery_providing_things = {
+                name: thing
+                for name, thing in self.all_ofm_things.items()
+                if thing.show_in_gallery
+            }
+        return self._gallery_providing_things