当我将 PyQt QProgressBar 与 Selenuim 一起使用时，它不起作用

2022-01-12 00:00:00 python selenium pyqt pyqt5 qprogressbar

问题描述

我构建了一个 PyQt5 GUI 来进行一些 Selenium 测试.一切都按预期工作，除了 PyQt 进度条.

I built a PyQt5 GUI to do some Selenium testing. Everything works as expected, except for the PyQt progress bar.

在下面的第一个示例中，我使用 Selenium 浏览器，最后，当浏览器关闭时，进度条会跳转到 100%.但是，Selenium 按预期工作.

In the first example below, where I use the Selenium browser, the progress bar just jumps to 100%, at the end, when the browser closes. But, the Selenium works as expected.

def test(self):
        self.completed = 0
        browser = webdriver.Firefox()
        links = ['http://www.somesite.com/', 'http://www.somesite.com/page2',
                 'http://www.somesite.com/page3']
        for link in links:
            browser.get(link)
            self.completed += 100 / len(links)
            time.sleep(2)
            print(link)
            self.progressBar.setValue(self.completed)
        browser.close()

但是，在下面的这个版本中，在注释掉 Selenium 浏览器的情况下，进度条按预期工作.

But, in this version below, with the Selenium browser commented out, the progress bar works as expected.

def test(self):
        self.completed = 0
        #browser = webdriver.Firefox()
        links = ['http://www.somesite.com/', 'http://www.somesite.com/page2',
                 'http://www.somesite.com/page3']
        for link in links:
            #browser.get(link)
            self.completed += 100 / len(links)
            time.sleep(2)
            print(link)
            self.progressBar.setValue(self.completed)
        #browser.close()

解决方案

阻塞任务对执行 GUI 的事件循环不友好，因为它们阻止了 GUI 执行的正常任务，例如票证检查、重绘等. 从被处决.

The blocking tasks are not friendly with the event loop where the GUI is executed as they prevent the normal tasks that the GUI performs such as ticket checking, redrawing, etc. from being executed.

在这些情况下的解决方案是使用线程执行阻塞任务并使用信号发送信息.

The solution in these cases is to use thread to execute the blocking task and use the signals to send the information.

import sys

from PyQt5 import QtCore, QtWidgets

from selenium import webdriver

class SeleniumWorker(QtCore.QObject):
    progressChanged = QtCore.pyqtSignal(int)
    def doWork(self):
        progress = 0
        browser = webdriver.Firefox()
        links = ['http://www.somesite.com/',
        'http://www.somesite.com/page2',
        'http://www.somesite.com/page3']
        for link in links:
            browser.get(link)
            progress += 100 / len(links)
            self.progressChanged.emit(progress)
        browser.close()

class Widget(QtWidgets.QWidget):
    def __init__(self, *args, **kwargs):
        QtWidgets.QWidget.__init__(self, *args, **kwargs)
        lay = QtWidgets.QHBoxLayout(self)
        progressBar = QtWidgets.QProgressBar()
        progressBar.setRange(0, 100)
        button = QtWidgets.QPushButton("Start")
        lay.addWidget(progressBar)
        lay.addWidget(button)
        self.thread = QtCore.QThread()
        self.worker = SeleniumWorker()
        self.worker.moveToThread(self.thread)
        self.thread.started.connect(self.worker.doWork)
        button.clicked.connect(self.thread.start)
        self.worker.progressChanged.connect(progressBar.setValue, QtCore.Qt.QueuedConnection)


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())

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