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# Copyright 2021-2025 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# -----------------------------------------------------------------------------
# Imports
# -----------------------------------------------------------------------------
from __future__ import annotations
import dataclasses
import enum
from collections.abc import Sequence
from bumble import att, device, gatt, gatt_adapters, gatt_client
# -----------------------------------------------------------------------------
# Constants
# -----------------------------------------------------------------------------
MIN_VOLUME = 0
MAX_VOLUME = 255
class ErrorCode(enum.IntEnum):
'''
See Volume Control Service 1.6. Application error codes.
'''
INVALID_CHANGE_COUNTER = 0x80
OPCODE_NOT_SUPPORTED = 0x81
class VolumeFlags(enum.IntFlag):
'''
See Volume Control Service 3.3. Volume Flags.
'''
VOLUME_SETTING_PERSISTED = 0x01
# RFU
class VolumeControlPointOpcode(enum.IntEnum):
'''
See Volume Control Service Table 3.3: Volume Control Point procedure requirements.
'''
# fmt: off
RELATIVE_VOLUME_DOWN = 0x00
RELATIVE_VOLUME_UP = 0x01
UNMUTE_RELATIVE_VOLUME_DOWN = 0x02
UNMUTE_RELATIVE_VOLUME_UP = 0x03
SET_ABSOLUTE_VOLUME = 0x04
UNMUTE = 0x05
MUTE = 0x06
@dataclasses.dataclass
class VolumeState:
volume_setting: int
mute: int
change_counter: int
@classmethod
def from_bytes(cls, data: bytes) -> VolumeState:
return cls(data[0], data[1], data[2])
def __bytes__(self) -> bytes:
return bytes([self.volume_setting, self.mute, self.change_counter])
# -----------------------------------------------------------------------------
# Server
# -----------------------------------------------------------------------------
class VolumeControlService(gatt.TemplateService):
UUID = gatt.GATT_VOLUME_CONTROL_SERVICE
EVENT_VOLUME_STATE_CHANGE = "volume_state_change"
volume_state: gatt.Characteristic[bytes]
volume_control_point: gatt.Characteristic[bytes]
volume_flags: gatt.Characteristic[bytes]
volume_setting: int
muted: int
change_counter: int
def __init__(
self,
step_size: int = 16,
volume_setting: int = 0,
muted: int = 0,
change_counter: int = 0,
volume_flags: int = 0,
included_services: Sequence[gatt.Service] = (),
) -> None:
self.step_size = step_size
self.volume_setting = volume_setting
self.muted = muted
self.change_counter = change_counter
self.volume_state = gatt.Characteristic(
uuid=gatt.GATT_VOLUME_STATE_CHARACTERISTIC,
properties=(
gatt.Characteristic.Properties.READ
| gatt.Characteristic.Properties.NOTIFY
),
permissions=gatt.Characteristic.Permissions.READ_REQUIRES_ENCRYPTION,
value=gatt.CharacteristicValue(read=self._on_read_volume_state),
)
self.volume_control_point = gatt.Characteristic(
uuid=gatt.GATT_VOLUME_CONTROL_POINT_CHARACTERISTIC,
properties=gatt.Characteristic.Properties.WRITE,
permissions=gatt.Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION,
value=gatt.CharacteristicValue(write=self._on_write_volume_control_point),
)
self.volume_flags = gatt.Characteristic(
uuid=gatt.GATT_VOLUME_FLAGS_CHARACTERISTIC,
properties=gatt.Characteristic.Properties.READ,
permissions=gatt.Characteristic.Permissions.READ_REQUIRES_ENCRYPTION,
value=bytes([volume_flags]),
)
super().__init__(
characteristics=[
self.volume_state,
self.volume_control_point,
self.volume_flags,
],
included_services=list(included_services),
)
def _on_read_volume_state(self, _connection: device.Connection) -> bytes:
return bytes(VolumeState(self.volume_setting, self.muted, self.change_counter))
def _on_write_volume_control_point(
self, connection: device.Connection, value: bytes
) -> None:
opcode = VolumeControlPointOpcode(value[0])
change_counter = value[1]
if change_counter != self.change_counter:
raise att.ATT_Error(ErrorCode.INVALID_CHANGE_COUNTER)
handler = getattr(self, '_on_' + opcode.name.lower())
if handler(*value[2:]):
self.change_counter = (self.change_counter + 1) % 256
connection.cancel_on_disconnection(
connection.device.notify_subscribers(attribute=self.volume_state)
)
self.emit(self.EVENT_VOLUME_STATE_CHANGE)
def _on_relative_volume_down(self) -> bool:
old_volume = self.volume_setting
self.volume_setting = max(self.volume_setting - self.step_size, MIN_VOLUME)
return self.volume_setting != old_volume
def _on_relative_volume_up(self) -> bool:
old_volume = self.volume_setting
self.volume_setting = min(self.volume_setting + self.step_size, MAX_VOLUME)
return self.volume_setting != old_volume
def _on_unmute_relative_volume_down(self) -> bool:
old_volume, old_muted_state = self.volume_setting, self.muted
self.volume_setting = max(self.volume_setting - self.step_size, MIN_VOLUME)
self.muted = 0
return (self.volume_setting, self.muted) != (old_volume, old_muted_state)
def _on_unmute_relative_volume_up(self) -> bool:
old_volume, old_muted_state = self.volume_setting, self.muted
self.volume_setting = min(self.volume_setting + self.step_size, MAX_VOLUME)
self.muted = 0
return (self.volume_setting, self.muted) != (old_volume, old_muted_state)
def _on_set_absolute_volume(self, volume_setting: int) -> bool:
old_volume_setting = self.volume_setting
self.volume_setting = volume_setting
return old_volume_setting != self.volume_setting
def _on_unmute(self) -> bool:
old_muted_state = self.muted
self.muted = 0
return self.muted != old_muted_state
def _on_mute(self) -> bool:
old_muted_state = self.muted
self.muted = 1
return self.muted != old_muted_state
# -----------------------------------------------------------------------------
# Client
# -----------------------------------------------------------------------------
class VolumeControlServiceProxy(gatt_client.ProfileServiceProxy):
SERVICE_CLASS = VolumeControlService
volume_control_point: gatt_client.CharacteristicProxy[bytes]
volume_state: gatt_client.CharacteristicProxy[VolumeState]
volume_flags: gatt_client.CharacteristicProxy[VolumeFlags]
def __init__(self, service_proxy: gatt_client.ServiceProxy) -> None:
self.service_proxy = service_proxy
self.volume_state = gatt_adapters.SerializableCharacteristicProxyAdapter(
service_proxy.get_required_characteristic_by_uuid(
gatt.GATT_VOLUME_STATE_CHARACTERISTIC
),
VolumeState,
)
self.volume_control_point = service_proxy.get_required_characteristic_by_uuid(
gatt.GATT_VOLUME_CONTROL_POINT_CHARACTERISTIC
)
self.volume_flags = gatt_adapters.DelegatedCharacteristicProxyAdapter(
service_proxy.get_required_characteristic_by_uuid(
gatt.GATT_VOLUME_FLAGS_CHARACTERISTIC
),
decode=lambda data: VolumeFlags(data[0]),
)
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