PyQt5在子线程中自动更新当前时间

Question

我想自动更新 Qstatusbar 中的当前时间。我使用 mainUI 线程来显示时间，并使用子线程来执行其他长时间运行的任务。这工作正常。

现在，我想使用子线程来显示时间。如下图，当我点击按钮3时，时间被冻结，而点击按钮1和按钮2时，时间正在运行。

import time
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *

class WorkerSignals(QObject):
    finished = pyqtSignal()
    result = pyqtSignal(object)

class Worker(QRunnable):
    def __init__(self, fn, *args, **kwargs):
        super(Worker, self).__init__()
        self.fn = fn
        self.args = args
        self.kwargs = kwargs
        self.signals = WorkerSignals()
    def run(self):
        result = self.fn(*self.args, **self.kwargs)
        self.signals.result.emit(result)
        self.signals.finished.emit()

class MainWindow(QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        self.threadpool = QThreadPool()
        self.set_main_layout()
        self.show_current_time()

    def set_main_layout(self):
        self.layout = QVBoxLayout()

        self.progress_bar = QProgressBar()
        self.progress_bar.setValue(0)

        self.btn1 = QPushButton('Sleep with thread')
        self.btn1.clicked.connect(self.btn1_onclick)

        self.btn2 = QPushButton('Sum with thread')
        self.btn2.clicked.connect(self.btn2_onclick)

        self.btn3 = QPushButton('Sleep without thread')
        self.btn3.clicked.connect(self.btn3_onclick)

        self.layout.addWidget(self.btn1)
        self.layout.addWidget(self.btn2)
        self.layout.addWidget(self.btn3)

        w = QWidget()
        w.setLayout(self.layout)
        self.setCentralWidget(w)

        self.status_bar = self.statusBar()
        self.status_bar.showMessage('Ready')
        self.time = QLabel()
        self.status_bar.addPermanentWidget(self.time)
        self.setStatusBar(self.status_bar)

    def show_current_time(self):
        self.timer = QTimer()
        self.timer.setInterval(1000)
        self.timer.timeout.connect(lambda: self.time.setText(QTime.currentTime().toString("hh:mm:ss")))
        self.timer.start()

    def btn1_onclick(self):
        worker = Worker(self.btn1_fn)
        worker.signals.result.connect(self.btn1_result)
        worker.signals.finished.connect(lambda: print('Btn1 finished...'))
        self.threadpool.start(worker)

    def btn1_fn(self):
        i = 0
        while i < 5:
            print(f'Btn1 sleeping...{i}')
            time.sleep(1)
            i += 1
        return i

    def btn1_result(self,i):
        pass

    def btn2_onclick(self):
        worker = Worker(self.btn2_fn)
        worker.signals.result.connect(self.btn2_result)
        worker.signals.finished.connect(lambda: print('Btn2 finished...'))
        self.threadpool.start(worker)

    def btn2_fn(self):
        sum=0
        print('Btn2 summing...')
        for i in range(50000000):
            sum+=1
        return sum

    def btn2_result(self, num):
        print(f'Btn2 sum: {num}')

    def btn3_onclick(self):
        i=0
        while i<5:
            print(f'Btn3 sleeping...{i}')
            time.sleep(1)
            i+=1

if __name__ == "__main__":
    app = QApplication([])
    window = MainWindow()
    window.show()
    app.exec_()

Answer 1

在 Qt（以及大多数其他 gui 框架）中，所有 gui 小部件都位于同一线程（称为 gui 线程）中。您不能像在 btn3_onclick 中尝试那样只冻结一个按钮。从 gui 线程调用 time.sleep(1) （就像你所做的那样）会冻结整个 gui 线程，这意味着它会冻结所有窗口和所有小部件。

您不需要线程定期更新 ui，只需使用计时器即可。 QTimer 不使用线程，它只是将事件安排到事件循环。

timer = QtCore.QTimer()
timer.timeout.connect(lambda: ui.label.setText(datetime.datetime.now().strftime("%H:%M:%S"))
timer.start(1000)