py: Support controls that are ControlTypeNone

Such controls can now be created when a control doesn't have a
reasonable or obvious default value. We support them using Python's
"None" value, rather than generating a runtime error.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Christian Rauch <Rauch.Christian@gmx.de>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/py/libcamera/py_helpers.cpp

@@ -55,6 +55,7 @@ py::object controlValueToPy(const ControlValue &cv)
 		return py::cast(v);
 	}
 	case ControlTypeNone:
+		return py::none();
 	default:
 		throw std::runtime_error("Unsupported ControlValue type");
 	}
@@ -91,6 +92,7 @@ ControlValue pyToControlValue(const py::object &ob, ControlType type)
 	case ControlTypeSize:
 		return ControlValue(ob.cast<Size>());
 	case ControlTypeNone:
+		return ControlValue();
 	default:
 		throw std::runtime_error("Control type not implemented");
 	}