libmidi_io: backends: Add RtMidi backend

Change-Id: If13f2dd94797296f1559ca8e1d2bf20785a5cf7d

Author: SebaUbuntu

libmidi_io/backends/rtmidi/__init__.py

@@ -0,0 +1,65 @@
+#
+# Copyright (C) 2022 Sebastiano Barezzi
+#
+# SPDX-License-Identifier: LGPL-3.0-or-later
+#
+"""MIDI I/O RtMidi backend."""
+
+from libmidi.types.messages.common import BaseMessage
+from mido.backends import rtmidi
+import rtmidi
+
+from libmidi_io.types.device import Device
+from libmidi_io.types.port import BasePort
+
+def get_devices():
+	devices = []
+
+	mi = rtmidi.MidiIn()
+	mo = rtmidi.MidiOut()
+
+	input_names = mi.get_ports()
+	output_names = mo.get_ports()
+
+	for name in input_names + output_names:
+		devices.append(Device(name, Port, name in input_names, name in output_names))
+
+	mi.delete()
+	mo.delete()
+
+	return devices
+
+class Port(BasePort):
+	def __init__(self, **kwargs):
+		super().__init__(**kwargs)
+
+		self._rt = rtmidi.MidiOut()
+
+		port_names = self._rt.get_ports()
+		if not port_names:
+			raise IOError("No ports available")
+
+		if self.name is None:
+			self.name = port_names[0]
+		if self.name not in port_names:
+			raise IOError(f"Unknown port {self.name!r}")
+
+		port_id = port_names.index(self.name)
+
+		try:
+			self._rt.open_port(port_id)
+		except RuntimeError as err:
+			raise IOError(*err.args)
+
+	def _close(self):
+		self._rt.close_port()
+		self._rt.delete()
+
+	def is_input(self) -> bool:
+		return False
+
+	def is_output(self) -> bool:
+		return True
+
+	def _send(self, message: BaseMessage):
+		self._rt.send_message(message.to_bytes())