pyqt5：qprogressbar不会更新

Question

我有一个应用程序，其中其中一个功能是使用Pytube下载YouTube视频。除了下载进度以更新Qprogressbar外，一切都很好。请参阅下面的代码：

import pytube

import PyQt5.QtWidgets as QtWidgets
import PyQt5.QtCore as QtCore


class Worker(QtCore.QObject):
    finished = QtCore.pyqtSignal()
    progress = QtCore.pyqtSignal(str, int, int)

    def __init__(self, url, save_path, fname):
        super(Worker, self).__init__()
        self.url = url
        self.save_path = save_path
        self.fname = fname
        self.perc_dl = 0

        self.download_video()

    def run(self):
        if self.perc_dl < 100:
            self.progress.emit('Downloading: {}%'.format(str(self.perc_dl)), int(self.perc_dl), 100)
            print(self.perc_dl)

        else:
            self.progress.emit('Done!', 100, 100)
            self.finished.emit()

    def download_video(self):
        yt = pytube.YouTube(self.url, on_progress_callback=self.progress_function)
        stream = yt.streams.filter(progressive=True, file_extension='mp4').get_highest_resolution()
        stream.download(output_path=self.save_path, filename=self.fname)

    def progress_function(self, stream, chunk, bytes_remaining):
        curr = stream.filesize - bytes_remaining
        per_downloaded = round((curr / stream.filesize) * 100, 1)
        self.perc_dl = per_downloaded
        self.run()


class DownloadFromYT(QtWidgets.QDialog):
    def __init__(self, url, save_path, fname):
        super(DownloadFromYT, self).__init__()
        self.url = url
        self.save_path = save_path
        self.fname = fname

        self.vLayoutMaster = QtWidgets.QVBoxLayout()
        self.hLayout = QtWidgets.QHBoxLayout()
        self.hLayout.setAlignment(QtCore.Qt.AlignRight)

        self.label = QtWidgets.QLabel()
        self.label.setText('Downloading video')

        self.pBar = QtWidgets.QProgressBar()
        self.pBar.setInvertedAppearance(True)
        self.pBar.setTextVisible(True)
        self.pBar.setFixedWidth(200)
        self.pBar.setAlignment(QtCore.Qt.AlignCenter)
        self.pBar.setMaximum(100)
        self.pBar.setFormat('Downloading: ')

        self.noButton = QtWidgets.QPushButton('No')
        self.noButton.setFixedWidth(50)
        self.noButton.hide()
        self.yesButton = QtWidgets.QPushButton('Yes')
        self.yesButton.setFixedWidth(50)
        self.yesButton.hide()

        self.vLayoutMaster.addWidget(self.label)
        self.vLayoutMaster.addSpacing(10)
        self.vLayoutMaster.addWidget(self.pBar)
        self.vLayoutMaster.addSpacing(20)
        self.hLayout.addWidget(self.noButton)
        self.hLayout.addWidget(self.yesButton)
        self.vLayoutMaster.addLayout(self.hLayout)

        # Signals / slots
        self.noButton.clicked.connect(self.reject)
        self.yesButton.clicked.connect(self.accept)

        # Widget
        self.setLayout(self.vLayoutMaster)
        self.setWindowTitle('Downloading')
        self.setFixedSize(250, 100)
        self.show()

        # Init download
        self.run_thread(url, save_path, fname)

    def run_thread(self, url, save_path, fname):
        self.thrd = QtCore.QThread()
        self.worker = Worker(url, save_path, fname)
        self.worker.moveToThread(self.thrd)

        self.thrd.start()
        self.thrd.started.connect(self.worker.run)
        self.worker.finished.connect(self.thrd.quit)
        self.worker.finished.connect(self.worker.deleteLater)
        self.worker.progress.connect(self.show_progress)
        self.thrd.finished.connect(self.thrd.deleteLater)

    def show_progress(self, label, n, total):
        self.pBar.setFormat(label)
        self.pBar.setMaximum(total)
        self.pBar.setValue(n)
        QtCore.QCoreApplication.processEvents()

        if label == 'Done!':
            self.thrd.quit()
            self.noButton.show()
            self.yesButton.show()
            self.label.setText('Video has been downloaded. Would you like to set the chosen\n'
                               'file path as the "Local file" path?')

我在应用程序的其他部分中使用了此基本结构来显示和更新进度栏，没有任何问题，但是由于某种原因，self.pbar当<<<代码>进度信号是从worker类发出的。如您所见，我在运行方法中有一个print（）语句，以检查代码实际上是否输入该，如果 block block和定期进行。将下载进度打印到控制台，这是。该应用程序完成运行后的应用程序会更新，因此我将获得最终的，完全填充的进度栏，但是在开始和结束之间，进度栏并未按预期进行更新。

任何帮助将不胜感激！

Answer 1

问题似乎是，尽管您努力正确地将所有这些线程工具组件连接起来，但您仍在主（UI）线程中运行self.download_video（）。因此，它阻止了UI的刷新。如果要在辅助线程中运行，则必须在worker.run（）函数中启动它，而不是worker构造函数。如果正确连接所有线程，则无需调用ProcessEvents（）以刷新UI。

如果不确定下载功能运行的线程，请在打印功能中打印线程ID，然后将其与主UI线程的线程ID进行比较。看看 https://doc.qt.io/qt.io/qt-5/ qthread.html＃CurrentThread