从 Python 线程更新 PyQt GUI

我有一个用 Designer (pyqt5) 制作的 GUI。我的主类中的函数需要在单独的线程上工作。我还在操作期间捕捉 QtextEdit LIVE 上的标准输出。到目前为止一切正常。

现在我正在尝试在我的主 GUI 窗体上实现一个 ProgressBar。该栏需要显示实时进度，就像在文本编辑上一样。

下面的示例代码在 Linux 上运行，没有任何警告。但在 Windows 上我收到错误：

QObject::setParent: Cannot set parent, new parent is in a different thread

我知道这是因为我在线程函数中修改了 ui 元素。我做了研究，但所有答案都指向使用 QThreads（就在我开始了解基本线程时！）。我更喜欢一种无需更改下面当前线程系统即可更新 GUI 的方法。

这是示例代码：

import sys
import threading
import time

from PyQt5.QtWidgets import QApplication, QMainWindow
from PyQt5.QtCore import QObject, pyqtSignal
from PyQt5.QtGui import QTextCursor

from ui_form import Ui_Form


class EmittingStream(QObject):
    textWritten = pyqtSignal(str)

    def write(self, text):
        self.textWritten.emit(str(text))


class Form(QMainWindow):
    finished = pyqtSignal()

    def __init__(self, parent=None):
        super(Form, self).__init__(parent)

        # Install the custom output stream
        sys.stdout = EmittingStream(textWritten=self.normalOutputWritten)

        self.ui = Ui_Form()
        self.ui.setupUi(self)

        self.ui.pushButton_run.clicked.connect(self.start_task)
        self.finished.connect(self.end_task)

    def start_task(self):

        self.thread = threading.Thread(target=self.run_test)
        self.thread.start()
        self.ui.pushButton_run.setEnabled(False)

    def end_task(self):
        self.ui.pushButton_run.setEnabled(True)

    def __del__(self):
        # Restore sys.stdout
        sys.stdout = sys.__stdout__

    def normalOutputWritten(self, text):
        """Append text to the QTextEdit."""
        cursor = self.ui.textEdit.textCursor()
        cursor.movePosition(QTextCursor.End)
        cursor.insertText(text)
        self.ui.textEdit.setTextCursor(cursor)
        self.ui.textEdit.ensureCursorVisible()

    def run_test(self):
        for i in range(100):
            per = i + 1
            self.ui.progressBar.setValue(per)
            print("%%%s" % per)
            time.sleep(0.15)  # simulating expensive task

        print("Task Completed!")
        time.sleep(1.5)
        self.ui.progressBar.reset()
        self.finished.emit()


def main():
    app = QApplication(sys.argv)
    form = Form()
    form.show()
    sys.exit(app.exec_())


if __name__ == "__main__":
    main()

the ui:

# -*- coding: utf-8 -*-
# Form implementation generated from reading ui file 'form.ui'
#
# Created: Mon Apr 30 13:43:19 2018
#      by: PyQt5 UI code generator 5.2.1
#
# WARNING! All changes made in this file will be lost!

from PyQt5 import QtCore, QtGui, QtWidgets


class Ui_Form(object):
    def setupUi(self, Form):
        Form.setObjectName("Form")
        Form.resize(800, 600)
        self.centralwidget = QtWidgets.QWidget(Form)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton_run = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton_run.setGeometry(QtCore.QRect(40, 20, 311, 191))
        self.pushButton_run.setObjectName("pushButton_run")
        self.textEdit = QtWidgets.QTextEdit(self.centralwidget)
        self.textEdit.setGeometry(QtCore.QRect(40, 230, 721, 241))
        self.textEdit.setObjectName("textEdit")
        self.progressBar = QtWidgets.QProgressBar(self.centralwidget)
        self.progressBar.setGeometry(QtCore.QRect(40, 490, 721, 23))
        self.progressBar.setObjectName("progressBar")
        Form.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(Form)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 25))
        self.menubar.setObjectName("menubar")
        Form.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(Form)
        self.statusbar.setObjectName("statusbar")
        Form.setStatusBar(self.statusbar)

        self.retranslateUi(Form)
        QtCore.QMetaObject.connectSlotsByName(Form)

    def retranslateUi(self, Form):
        _translate = QtCore.QCoreApplication.translate
        Form.setWindowTitle(_translate("Form", "MainWindow"))
        self.pushButton_run.setText(_translate("Form", "RUN"))

不知何故，我需要立即通知 gui 线程（从我正在运行的线程）进度条值正在更改（这个过程可能需要几分钟才能完成）。

定义一个将更新发送到进度栏的自定义信号：

class Form(QMainWindow):
    finished = pyqtSignal()
    updateProgress = pyqtSignal(int)

    def __init__(self, parent=None):
        super(Form, self).__init__(parent)
        ...
        self.updateProgress.connect(self.ui.progressBar.setValue)

    def run_test(self):
        for i in range(100):
            per = i + 1
            self.updateProgress.emit(per)
            ...