虽然我的应用程序做了一些耗时的事情,但我希望在应用程序繁忙时向用户显示一个消息框。我不想要任何按钮(如OK
或Cancel
),我不能在消息框上调用exec_()
,因为这是阻塞。
我检查了一些qt
网站,我需要的代码似乎归结为:
message_box = QMessageBox()
message_box.setText(str('Reading Device, Please Wait...'))
message_box.show()
# do work here
message_box.close()
当我运行代码时,我得到了消息框,但没有文本。我究竟做错了什么?
我在下面列出了一个工作示例:
#!/usr/bin/env python3
import sys
import time
from PySide2.QtWidgets import (QLineEdit, QPushButton, QApplication,
QVBoxLayout, QDialog, QMessageBox)
class Form(QDialog):
def __init__(self, parent=None):
super(Form, self).__init__(parent)
self.button = QPushButton("Click Me")
layout = QVBoxLayout()
layout.addWidget(self.button)
self.setLayout(layout)
# Add button signal to dowork slot
self.button.clicked.connect(self.dowork)
def dowork(self):
message_box = QMessageBox()
message_box.setText(str('Reading Device, Please Wait...'))
message_box.show()
delay = 2.5
while delay:
sys.stdout.write('Working...\n')
time.sleep(0.5) # do some time-consuming stuff...
delay -= 0.5
message_box.close()
if __name__ == '__main__':
app = QApplication(sys.argv)
form = Form()
print('starting app...')
form.show()
sys.exit(app.exec_())
如果单击该按钮,将弹出消息框,并在“工作”完成时显示。当“工作”完成后,消息框将再次消失 - 正如它应该的那样。但是消息框中没有显示任何文本。
这里有一个类似的问题:qmessagebox-not-show-text-when-call-show,但这不回答我的问题。
您不能拥有耗费大量时间(超过30毫秒)的任务,因为它阻止了GUI事件循环,阻止Qt正常工作,而是使用信号旁边的线程从另一个线程更新GUI:
import sys
import threading
import time
from PySide2 import QtCore, QtWidgets
class Form(QtWidgets.QDialog):
started = QtCore.Signal()
finished = QtCore.Signal()
def __init__(self, parent=None):
super(Form, self).__init__(parent)
self.button = QtWidgets.QPushButton("Click Me")
layout = QtWidgets.QVBoxLayout(self)
layout.addWidget(self.button)
# Add button signal to dowork slot
self.button.clicked.connect(self.on_clicled)
self._message_box = QtWidgets.QMessageBox()
self._message_box.setText(str('Reading Device, Please Wait...'))
self._message_box.setStandardButtons(QtWidgets.QMessageBox.NoButton)
self.started.connect(self._message_box.show)
self.finished.connect(self._message_box.accept)
@QtCore.Slot()
def on_clicled(self):
thread = threading.Thread(target=self.dowork, daemon=True)
thread.start()
def dowork(self):
delay = 2.5
self.started.emit()
while delay:
sys.stdout.write('Working...\n')
time.sleep(0.5) # do some time-consuming stuff...
delay -= 0.5
self.finished.emit()
if __name__ == '__main__':
app = QtWidgets.QApplication(sys.argv)
form = Form()
print('starting app...')
form.show()
sys.exit(app.exec_())
你几乎肯定会使用QProgressDialog。将“不确定”外观设置为最小值和最大值为零。
https://doc.qt.io/qt-5/qprogressdialog.html
虽然在setText()
之后强制重绘可能会产生奇迹:
self._message_box.repaint()
QtWidgets.QApplication.processEvents()