问如何在初始化大数据时显示进度条
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Stack Overflow用户

提问于 2021-04-22 12:53:21

回答 1查看 51关注 0票数 0

我使用的是PyQt5。在下面代码的MainWindow.__init__过程中，我想初始化一些需要很长时间(例如20秒)的大数据(参见MainWindow.initData)。在此期间，我想显示一个进度条。只有在app.exec_()开始执行之后，才能显示进度条，因此我不能从MainWindow.__init__中调用initData。因此，我试图通过发布一个事件(postEvent)来执行initData，该事件将导致initData在app.exec_执行时执行。我查看了stackoverflow中的一些示例，并获得了以下代码。虽然会发布事件并调用initData，但直到initData完成后才会显示进度条。

请建议如何修改代码，以便在执行initData时显示进度条。谢谢。

import sys
from PyQt5 import QtWidgets
from PyQt5.QtCore import QEvent

class MyEvent(QEvent):
    idType = QEvent.registerEventType()

    def __init__(self, data):
        QEvent.__init__(self, MyEvent.idType)
        self.data = data
        print("MyEvent.idType ", MyEvent.idType)

    def get_data(self):
        return self.data

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)

        self.setWindowTitle("My MainWindow")
        self.qProgressBar = QtWidgets.QProgressBar(self)
        self.qProgressBar.setGeometry(100, 100, 200, 30)

        self.label = QtWidgets.QLabel("Hello", self)
        self.label.setGeometry(50, 50, 200, 20)

        tempEvent = MyEvent("12345")
        QtWidgets.QApplication.postEvent(self, tempEvent)

    def initData(self):
        # To demonstrate, do something that takes a long time (for example
        # 20 seconds) and update progress bar.
        print("begin initData")
        loop = 10000
        for i in range(loop):
            self.qProgressBar.setValue(int((i+1)/loop*100))
            for j in range(loop):
                temp = i + j

    def customEvent(self, event):
        print("customEvent:", event.type())
        if (event.type() == MyEvent.idType):
            self.label.setText("Received : {0}".format(event.get_data()))
            self.initData()
    
if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)

    w = MainWindow()
    screen = QtWidgets.QDesktopWidget().screenGeometry()
    w.setGeometry(screen.width()//2-200, screen.height()//2-200, 400, 400) # x, y, Width, Height
    w.show()
    
    sys.exit(app.exec_())

pyqt5

initialization

python

events

回答 1

Stack Overflow用户

回答已采纳

发布于 2021-04-22 14:02:50

谢谢你。这是工作的最终结果！

import sys
from PyQt5 import QtWidgets
from PyQt5.QtCore import QObject, QThread, pyqtSignal
from time import sleep

class Worker_InitData(QObject):
    finished = pyqtSignal()
    progress = pyqtSignal(int)

    def run(self):
        """Long-running task."""
        for i in range(10):
            sleep(1)
            self.progress.emit(i)
        self.finished.emit()

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)

        self.setWindowTitle("My MainWindow")
        self.qProgressBar = QtWidgets.QProgressBar(self)
        self.qProgressBar.setGeometry(100, 100, 200, 30)

        self.label = QtWidgets.QLabel("Hello", self)
        self.label.setGeometry(50, 50, 200, 20)

        self.initData()

    def reportProgress(self, i):
        self.qProgressBar.setValue(int((i+1)/10*100))
    
    def initData(self):
        # Step 2: Create a QThread object
        self.thread = QThread()
        # Step 3: Create a worker object
        self.worker = Worker_InitData()
        # Step 4: Move worker to the thread
        self.worker.moveToThread(self.thread)
        # Step 5: Connect signals and slots
        self.thread.started.connect(self.worker.run)
        self.worker.finished.connect(self.thread.quit)
        self.worker.finished.connect(self.worker.deleteLater)
        self.thread.finished.connect(self.thread.deleteLater)
        self.worker.progress.connect(self.reportProgress)
        # Step 6: Start the thread
        self.thread.start()
   
if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)

    w = MainWindow()
    screen = QtWidgets.QDesktopWidget().screenGeometry()
    w.setGeometry(screen.width()//2-200, screen.height()//2-200, 400, 400) # x, y, Width, Height
    w.show()
    
    sys.exit(app.exec_())