为什么外部函数会导致 PyQt5 window 冻结？

Question

这是一些中断的示例代码：

import sys
import time
from PyQt5.QtWidgets import (QApplication, QDialog,
                             QProgressBar)

class Actions(QDialog):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.progress = QProgressBar(self)
        self.progress.setGeometry(0, 0, 300, 25)
        self.show()

        self.count = 0

        while self.count < 100:
            self.count += 1
            time.sleep(1) # Example external function
            self.progress.setValue(self.count)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = Actions()
    sys.exit(app.exec_())

运行这将导致它冻结并变得无响应，特别是在 windows 环境中。用任何非 PyQt5 函数替换 time.sleep 函数将产生相同的结果。

据我了解，这与未使用 QThread 在单独的线程中调用该函数有关。我使用 this answer 作为参考并提出了部分解决方案。

import sys
import time

from PyQt5.QtCore import QThread
from PyQt5.QtWidgets import (QApplication, QDialog,
                             QProgressBar)

class External(QThread):

    def run(self):
        count = 0

        while count < 100:
            count += 1
            print(count)
            time.sleep(1)

class Actions(QDialog):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.progress = QProgressBar(self)
        self.progress.setGeometry(0, 0, 300, 25)
        self.show()

if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = Actions()
    calc = External()
    calc.finished.connect(app.exit)
    calc.start()
    sys.exit(app.exec_())

这将在后台运行 time.sleep 并保持主要 window 响应。但是，我不知道如何使用 self.progress.setValue 更新值，因为在 class External.

中无法访问它

据我所知，我必须使用信号来完成此操作。大多数文档都是针对 PyQt4 的，这使得找到解决方案变得更加困难。

我面临的另一个问题是能够从 class Actions.

中启动 External 线程

此问题的答案也将作为 PyQt5 的宝贵文档。提前致谢。

Answer 1

您必须使用信号来更新值。

import sys
import time

from PyQt5.QtCore import QThread, pyqtSignal
from PyQt5.QtWidgets import (QApplication, QDialog,
                             QProgressBar)

class External(QThread):
    countChanged = pyqtSignal(int)
    def run(self):
        count = 0

        while count < 100:
            count += 1
            self.countChanged.emit(count)
            print(count)
            time.sleep(1)

class Actions(QDialog):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.progress = QProgressBar(self)
        self.progress.setGeometry(0, 0, 300, 25)
        self.show()

    def onCountChanged(self, value):
        self.progress.setValue(value)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = Actions()
    calc = External()
    calc.countChanged.connect(window.onCountChanged)
    calc.start()
    sys.exit(app.exec_())

Answer 2

这是一个从 class Actions 内部启动线程并使用按钮的版本：

import sys
import time

from PyQt5.QtCore import QThread, pyqtSignal
from PyQt5.QtWidgets import (QApplication, QDialog,
                             QProgressBar, QPushButton)

class External(QThread):

    countChanged = pyqtSignal(int)

    def run(self):
        count = 0

        while count < 100:
            count += 1
            time.sleep(1)
            print(count)
            self.countChanged.emit(count)

class Actions(QDialog):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        self.progress = QProgressBar(self)
        self.progress.setGeometry(0, 0, 300, 25)
        self.button = QPushButton('Start', self)
        self.button.move(0, 30)
        self.show()

        self.button.clicked.connect(self.onButtonClick)

    def onButtonClick(self):
        self.calc = External()
        self.calc.countChanged.connect(self.onCountChanged)
        self.calc.start()

    def onCountChanged(self, value):
        self.progress.setValue(value)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = Actions()
    sys.exit(app.exec_())

为什么外部函数会导致 PyQt5 window 冻结？

Why do external functions cause the PyQt5 window to freeze?

python

pyqt

qthread

pyqt5

python-3.5