wip test async comparison using QT signals

src/capture_method/__init__.py

@@ -1,11 +1,14 @@
 import os
 import sys
 from collections import OrderedDict
+from collections.abc import Callable
 from dataclasses import dataclass
 from enum import EnumMeta, StrEnum, auto, unique
 from itertools import starmap
 from typing import TYPE_CHECKING, Never, TypedDict, cast
 
+from cv2.typing import MatLike
+from PySide6 import QtCore
 from typing_extensions import override
 
 from capture_method.CaptureMethodBase import CaptureMethodBase
@@ -221,3 +224,27 @@ def get_camera_info(index: int, device_name: str):
         for camera_info in starmap(get_camera_info, enumerate(named_video_inputs))
         if camera_info is not None
     ]
+
+
+class CaptureMethodSignal(QtCore.QObject):
+    """Made to look like a `QtCore.SignalInstance`, but with safe `connect`/`disconnect` methods."""
+
+    __frame_signal = QtCore.Signal(object)
+
+    def subscribe_to_new_frame(self, slot: Callable[[MatLike | None], object]):
+        try:
+            return self.__frame_signal.connect(slot, QtCore.Qt.ConnectionType.UniqueConnection)
+        except RuntimeError:
+            pass
+
+    def unsubscribe_from_new_frame(self, slot: Callable[[MatLike | None], object]):
+        try:
+            self.__frame_signal.disconnect(slot)
+        except RuntimeError:
+            pass
+
+    def _push_new_frame_to_subscribers(self, frame: MatLike | None, /):
+        return self.__frame_signal.emit(frame)
+
+    def __init__(self):
+        super().__init__()