我有一个应用程序,在其中我在第二个线程中运行某些进程,并在一定条件下在某个点打开另一个对话框窗口,该对话框将暂停该进程,直到您确认某些内容为止。这将导致以下错误消息:
QObject: Cannot create children for a parent that is in a different thread.
(Parent is QApplication(0x1f9c82383d0), parent's thread is QThread(0x1f9c7ade2a0), current thread is QThread(0x1f9c8358800)
有趣的是,如果您还在进程运行时并且在弹出新对话框之前将光标移到MainWindow
上,它还会多次产生此错误消息:
QBasicTimer::stop: Failed. Possibly trying to stop from a different thread
非常奇怪。因为如果将光标移到MainWindow
上,则会发生only。
现在,在我的应用程序中,我实际上为使用PyQt5.uic.loadUi
弹出的新对话框加载了一个界面,这没有引起任何问题。但是,当我为本文创建示例时,由于我在初始化新对话框时设置其布局,因此又发生了另一个问题:
QObject::setParent: Cannot set parent, new parent is in a different thread
导致应用程序崩溃的原因:
Process finished with exit code -1073741819 (0xC0000005)
我显然在这里就我猜想的线程做错了,但是我不知道是什么。我感到特别困惑的是,在使用loadUi
完全可以的同时,我无法在初始化期间设置新对话框的布局。这是我的示例代码:
import sys
import time
import numpy as np
from PyQt5.QtCore import QObject, pyqtSignal, QThread
from PyQt5.QtWidgets import (
QDialog, QApplication, QPushButton, QGridLayout, QProgressBar, QLabel
)
class SpecialDialog(QDialog):
def __init__(self):
super().__init__()
btn = QPushButton('pass variable')
btn.clicked.connect(self.accept)
layout = QGridLayout()
layout.addWidget(btn)
# self.setLayout(layout)
self.variable = np.random.randint(0, 100)
class Handler(QObject):
progress = pyqtSignal(int)
finished = pyqtSignal(int)
def __init__(self):
super().__init__()
self._isRunning = True
self._success = False
def run(self):
result = None
i = 0
while i < 100 and self._isRunning:
if i == 50:
dialog = SpecialDialog()
dialog.exec_()
result = dialog.variable
time.sleep(0.01)
i += 1
self.progress.emit(i)
if i == 100:
self._success = True
self.finished.emit(result)
def stop(self):
self._isRunning = False
class MainWindow(QDialog):
def __init__(self):
super().__init__()
btn = QPushButton('test')
btn.clicked.connect(self.run_test)
self.pbar = QProgressBar()
self.resultLabel = QLabel('Result:')
layout = QGridLayout(self)
layout.addWidget(btn)
layout.addWidget(self.pbar)
layout.addWidget(self.resultLabel)
self.setLayout(layout)
self.handler = None
self.handler_thread = QThread()
self.result = None
def run_test(self):
self.handler = Handler()
self.handler.moveToThread(self.handler_thread)
self.handler.progress.connect(self.progress)
self.handler.finished.connect(self.finisher)
self.handler_thread.started.connect(self.handler.run)
self.handler_thread.start()
def progress(self, val):
self.pbar.setValue(val)
def finisher(self, result):
self.result = result
self.resultLabel.setText(f'Result: {result}')
self.pbar.setValue(0)
self.handler.stop()
self.handler.progress.disconnect(self.progress)
self.handler.finished.disconnect(self.finisher)
self.handler_thread.started.disconnect(self.handler.run)
self.handler_thread.terminate()
self.handler = None
if __name__ == '__main__':
app = QApplication(sys.argv)
GUI = MainWindow()
GUI.show()
sys.exit(app.exec_())
编辑
[我忘了提到我已经找到this post了,这可能与我的问题有关,但是,我并不理解最佳答案中该解决方案的原因,更重要的是,我不会说我所讲的相信是C ++。
您无法从辅助线程创建或修改GUI元素,并且错误消息对此进行了指示。
您必须重新设计Handler类,根据您的要求,您必须将run划分为2个方法,第一个方法将生成多达50%的进度,其中GUI将打开对话框,获取结果并启动第二个方法。
import sys
import time
import numpy as np
from functools import partial
from PyQt5.QtCore import QObject, pyqtSignal, pyqtSlot, QThread, QTimer
from PyQt5.QtWidgets import (
QDialog,
QApplication,
QPushButton,
QGridLayout,
QProgressBar,
QLabel,
)
class SpecialDialog(QDialog):
def __init__(self):
super().__init__()
btn = QPushButton("pass variable")
btn.clicked.connect(self.accept)
layout = QGridLayout()
layout.addWidget(btn)
# self.setLayout(layout)
self.variable = np.random.randint(0, 100)
class Handler(QObject):
progress = pyqtSignal(int)
finished = pyqtSignal(int)
def __init__(self):
super().__init__()
self._isRunning = True
self._success = False
@pyqtSlot()
def task1(self):
i = 0
while i <= 50 and self._isRunning:
time.sleep(0.01)
i += 1
self.progress.emit(i)
@pyqtSlot(int)
def task2(self, result):
i = 50
while i < 100 and self._isRunning:
time.sleep(0.01)
i += 1
self.progress.emit(i)
if i == 100:
self._success = True
self.finished.emit(result)
def stop(self):
self._isRunning = False
class MainWindow(QDialog):
def __init__(self):
super().__init__()
btn = QPushButton("test")
btn.clicked.connect(self.run_test)
self.pbar = QProgressBar()
self.resultLabel = QLabel("Result:")
layout = QGridLayout(self)
layout.addWidget(btn)
layout.addWidget(self.pbar)
layout.addWidget(self.resultLabel)
self.setLayout(layout)
self.handler = None
self.handler_thread = QThread()
self.result = None
def run_test(self):
self.handler = Handler()
self.handler.moveToThread(self.handler_thread)
self.handler.progress.connect(self.progress)
self.handler.finished.connect(self.finisher)
self.handler_thread.started.connect(self.handler.task1)
self.handler_thread.start()
@pyqtSlot(int)
def progress(self, val):
self.pbar.setValue(val)
if val == 50:
dialog = SpecialDialog()
dialog.exec_()
result = dialog.variable
wrapper = partial(self.handler.task2, result)
QTimer.singleShot(0, wrapper)
def finisher(self, result):
self.result = result
self.resultLabel.setText(f"Result: {result}")
self.pbar.setValue(0)
self.handler.stop()
self.handler_thread.quit()
self.handler_thread.wait()
if __name__ == "__main__":
app = QApplication(sys.argv)
GUI = MainWindow()
GUI.show()
sys.exit(app.exec_())