python - While True Loop 中的 USB 事件捕获

Question

我希望在“while True”循环中捕获单个 USB 键盘事件，该循环还包括一个计时器功能。Evdev 接近我所需要的，但它的 device.read_loop 不允许包含时钟功能 - 它是一个闭环。关于如何捕获一个我可以在检查时控制的 USB 键盘事件的任何想法？我使用的是 Python 3.4，所以 asyncio 不是一个选项。谢谢你。

Answer 1

线程将在这里为您提供帮助。正如Python 本周模块 (PyMOTW)所说：

使用线程允许程序在同一进程空间中同时运行多个操作。

在您的情况下，您仍然可以在自己的线程中的阻塞循环中读取键盘输入，并让 sleep 函数检查另一个线程中的时间，而不会被 evdev 的 read_loop 阻塞。只需将 radio_sleep_time 设置为您希望等到收音机休眠的秒数（您可以使用分钟而radio_sleep_time = 4 * 60不是 4 分钟）。

from time import time
from threading import Thread
from evdev import *

radio_sleep_time = 4  # sleep time for radio in seconds
device = InputDevice('/dev/input/event3')  # pick the right keyboard you want to use


def read_kb():
    for event in device.read_loop():
        # only use key events AND only key down can be changed depending on your use case.
        if event.type == ecodes.EV_KEY and event.value == 1:
            keyevent = categorize(event)  # just used here to have something nice to print
            print(keyevent)  # print key pressed event


def wait_loop():
    pass  # whatever radio is doing when its waiting to sleep if anything.


class Time1(Thread):
    def run(self):
        while True:
            read_kb()


class Time2(Thread):
    def run(self):
        t0 = time()  # starting time
        # time() (current time) - t0 (starting time) gives us the time elapsed since starting
        while not time() - t0 > radio_sleep_time:  # loop until time passed is greater than sleep_time
            wait_loop()  # do sleep stuff
        print(time() - t0, ">", radio_sleep_time)
        print("SLEEP")
        # sleep radio here
        # but continue to listen to keyboard


Time1().start()
Time2().start()