ScreenSaver/backend/medr-screensaver-backend.py

#!/usr/bin/env python2.7
# -*- coding: utf-8 -*-
"""
Author: Zhang Yueqian zhangyueqian@antiy.cn
Date: 2022-10-31 11:20:48
LastEditors: Zhang Yueqian zhangyueqian@antiy.cn
LastEditTime: 2022-10-31 11:34:00
FilePath: /screensaver/backend/medr-screensaver-backend.py
Description: 屏保程序 for MEDR项目. 本文件为后台监控的部分.

原理: 主要负责实现两部分功能
1. 通过dbus方法提供开始菜单中的锁屏功能
2. 通过监听org.gnome.SessionManager.Presence的StatusChanged信号完成自动锁屏功能
以上两种锁屏通过调用 medr-screensaver-command 来实现, 提供不同的参数 `--session-idle` 和 `--lock`

另外: 对于锁屏情况下的黑屏时长, 需要控制lightdm配置实现, 参考
https://askubuntu.com/questions/403859/how-to-control-lightdm-power-saving-preferences
利用额外的文件 /var/run/medr-lightdm 来设置
"""

from datetime import datetime
import threading
from time import sleep
import dbus
import dbus.service
import dbus.glib
import os

import gi

gi.require_version("Gtk", "3.0")
from gi.repository import GObject, Gio


BUS_NAME = "org.ukui.ScreenSaver"
TIMEOUT_FILE = "/var/run/medr-lightdm"
LOCK_FILE = "/var/run/medr-lightdm-lock"
DEFAULT_TIMEOUT = 10


class Service(dbus.service.Object):
    """锁屏dbus服务"""

    def __init__(self, bus_name, obj_path):
        """使用bus_name和obj_path初始化dbus服务

        Args:
            bus_name (dbus.service.BusName): 要注册的bus名
            obj_path (str): 要注册的路径
        """
        dbus.service.Object.__init__(self, bus_name, obj_path)
        self._locked = False

    @dbus.service.method(BUS_NAME, in_signature="", out_signature="b")
    def GetLockState(self):
        print("GetLockState: %s" % self._locked)
        return self._locked

    @dbus.service.method(BUS_NAME, in_signature="b", out_signature="")
    def SetLockState(self, state):
        print("SetLockState: %s" % state)
        self._locked = state

    @dbus.service.method(BUS_NAME, in_signature="", out_signature="")
    def Lock(self):
        print("Lock")
        self._locked = True
        os.system("ukui-screensaver-dialog --lock")

    @dbus.service.method(BUS_NAME, in_signature="", out_signature="")
    def Quit(self):
        self._loop.quit()

    @dbus.service.signal(BUS_NAME)
    def SessionIdle(self):
        os.system("ukui-screensaver-dialog --session-idle")


loop = GObject.MainLoop()
bus = dbus.SessionBus()
bus_name = dbus.service.BusName(BUS_NAME, bus=bus)
service = Service(bus_name, "/")


def isLocked():
    """确认当前是否是锁定状态.

    Returns:
        boolean: 是否锁定.
    """
    if not os.path.exists(LOCK_FILE):
        return False

    status = ""
    with open(LOCK_FILE, "r") as fp:
        status = fp.readline().strip()

    if len(status) != 0 and status == "done":
        return True

    return False


def sessionStatusChanged(sessionStatus):
    print("---- Caught signal of status %s ----" % sessionStatus)

    if sessionStatus == 3 and (not isLocked()):
        service.SessionIdle()

    print("\n")


def checkSessionIdle():
    """检查gsettings中配置的会话闲置时间并写入到配置文件 TIMEOUT_FILE 中"""
    while True:
        mate_session = Gio.Settings("org.mate.session")
        sys_timeout = mate_session.get_value("idle-delay").get_int32()

        with open(TIMEOUT_FILE, "r") as fp:
            try:
                medr_timeout = int(fp.read())
            except ValueError:
                medr_timeout = DEFAULT_TIMEOUT

        if medr_timeout != sys_timeout:
            with open(TIMEOUT_FILE, "w") as fp:
                fp.write("%s" % sys_timeout)

        sleep(5)


t = threading.Thread(target=checkSessionIdle)


if __name__ == "__main__":
    bus.add_signal_receiver(
        sessionStatusChanged, dbus_interface="org.gnome.SessionManager.Presence", signal_name="StatusChanged"
    )
    # org.gnome.SessionManager.Presence:StatusChanged
    t.start()
    loop.run()