使用 QDial 更改简单的 Python 计时器的时间

Question

我想创建一个小型 python 应用程序，每 n 秒在控制台中打印一条消息。 我还使用 PyQt 来创建用户界面。 我想使用 QDial 更改消息之间的时间段，但是当我更改 sliderMoved 方法上的时间变量值时，时间不会更改。

import sys
from threading import Timer,Thread,Event
from datetime import datetime

from PyQt5.QtWidgets import QApplication, QLabel, QPushButton
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QGridLayout, QDial
from PyQt5.QtGui import QIcon
from PyQt5.QtCore import pyqtSlot

stopFlag = Event()
time = 2

class MyThread(Thread):

    def __init__(self, event):
        Thread.__init__(self)
        self.stopped = event

    def run(self):
        while not self.stopped.wait(time):
            print('Message')


def startThread():
    stopFlag.clear()
    thread = MyThread(stopFlag)
    thread.start()

def start_clicked():
    print("Start clicked")
    startThread()

def stop_clicked():
    print("Stop clicked")   
    stopFlag.set()


class Window(QWidget):
    def __init__(self):
        QWidget.__init__(self)
        layout = QGridLayout()
        self.setLayout(layout)

        self.start_btn = QPushButton(self)
        self.start_btn.setText("Start")
        self.start_btn.clicked.connect(start_clicked)
        layout.addWidget(self.start_btn)

        self.stop_btn = QPushButton(self)
        self.stop_btn.setText("Stop")
        self.stop_btn.clicked.connect(stop_clicked)
        layout.addWidget(self.stop_btn)

        self.dial = QDial()
        self.dial.setMinimum(1)
        self.dial.setMaximum(10)
        self.dial.setValue(2)
        self.dial.valueChanged.connect(self.sliderMoved)
        layout.addWidget(self.dial)

    def sliderMoved(self):
        print("Dial value = %i" % (self.dial.value()))
        time = self.dial.value()

app = QApplication(sys.argv)
screen = Window()
screen.show()
sys.exit(app.exec_())

Answer 1

函数在 python 中有自己的作用域：

time = 5

def foo():
    time = 10 # only local, not changing the global time.
    print(time)

foo()  # prints 10
print(time) # prints 5

您应该尽可能避免使用全局状态。 在这里，我向您的MyThread对象添加方法和时间属性，并更改此对象的时间值以使其工作。 我还将事件移到类中并添加了一个停止方法。

import sys
from threading import Thread, Event
import time

from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QGridLayout, QDial

START_TIME = time.time()


def elapsed():
    return round(time.time() - START_TIME, 1)


class MyThread(Thread):
    def __init__(self, time):
        super().__init__() # call __init__ of the baseclass
        self.time = time
        self.stopped = Event()

    def run(self):
        while not self.stopped.wait(self.time):
            print(elapsed(), 'Message')

    # Thread has a method start, here we add the clearing to the signal
    def start(self):
        print(elapsed(), 'Started')
        self.stopped.clear()
        super().start()

    # new method stop
    def stop(self):
        print(elapsed(), 'Stopped')
        self.stopped.set()


class Window(QWidget):
    def __init__(self):
        QWidget.__init__(self)
        layout = QGridLayout()
        self.setLayout(layout)

        self.thread = MyThread(time=2)
        self.start_btn = QPushButton(self)
        self.start_btn.setText("Start")
        self.start_btn.clicked.connect(self.thread.start)
        layout.addWidget(self.start_btn)

        self.stop_btn = QPushButton(self)
        self.stop_btn.setText("Stop")
        self.stop_btn.clicked.connect(self.thread.stop)
        layout.addWidget(self.stop_btn)

        self.dial = QDial()
        self.dial.setMinimum(1)
        self.dial.setMaximum(10)
        self.dial.setValue(self.thread.time)
        self.dial.valueChanged.connect(self.sliderMoved)
        layout.addWidget(self.dial)

    def sliderMoved(self):
        print(elapsed(), "Dial value = %i" % (self.dial.value()))
        self.thread.time = self.dial.value()


app = QApplication(sys.argv)
screen = Window()
screen.show()
sys.exit(app.exec_())