PyQT4 QWidget 在关闭前必须接收两次 'close' 信号
PyQT4 QWidget must receive 'close' signal twice before closing
我正在编写一个 PyQT4 (4.11) 程序，该程序执行一个长时间缓慢的任务，理想情况下需要一个进度条。如果我不使用线程、子classing 一个只包含一个QProgressBar 和一个布局的QWidget，该程序几乎可以完美运行。将这个子 class 实例化为 form，我可以调用 form.show() 将其显示在屏幕上，然后我的长慢循环可以通过调用 form.progressbar.setValue(progress) 来更新进度。这有两个问题：
如果用户尝试与 window 交互，他们会从 windows manager/OS 桌面进程收到 'not responding' 消息。这是因为事件没有被处理。
因为事件没有被处理，用户不能通过关闭 window.
所以我尝试在单独的线程中制作长而慢的循环 运行，使用信号更新进度条。我覆盖了我的 QWidget 的 closeEvent，以便它可以取消与硬件设备的交互（全部包装在互斥体中，因此设备通信不会不同步）。同样，这几乎可行。如果我取消，应用程序将退出。如果我让它完成 运行，我必须手动关闭 window（即单击关闭图标或按 alt-f4），即使我正在向 QWidget 发送关闭信号。正如您在下面的代码中看到的那样，有一些复杂情况，因为如果取消应用程序不能立即关闭，因为它必须等待一些硬件清理发生。这是我的代码的最小版本
import sys
import os
import time
from PyQt4 import QtCore, QtGui
class Ui_ProgressBarDialog(QtGui.QWidget):
def __init__(self, on_close=None):
QtGui.QWidget.__init__(self)
self.setupUi(self)
self.center()
#on_close is a function that is called to cancel
#the long slow loop
self.on_close = on_close
def center(self):
qr = self.frameGeometry()
cp = QtGui.QDesktopWidget().availableGeometry().center()
qr.moveCenter(cp)
self.move(qr.topLeft())
def setupUi(self, ProgressBarDialog):
ProgressBarDialog.setObjectName(_fromUtf8("ProgressBarDialog"))
ProgressBarDialog.resize(400, 33)
self.verticalLayout = QtGui.QVBoxLayout(ProgressBarDialog)
self.verticalLayout.setObjectName(_fromUtf8("verticalLayout"))
self.progressBar = QtGui.QProgressBar(ProgressBarDialog)
self.progressBar.setProperty("value", 0)
self.progressBar.setObjectName(_fromUtf8("progressBar"))
self.verticalLayout.addWidget(self.progressBar)
self.retranslateUi(ProgressBarDialog)
#This allows the long slow loop to update the progress bar
QtCore.QObject.connect(
self,
QtCore.SIGNAL("updateProgress"),
self.progressBar.setValue
)
#Catch the close event so we can interrupt the long slow loop
QtCore.QObject.connect(
self,
QtCore.SIGNAL("closeDialog"),
self.closeEvent
)
#Repaint the window when the progress bar's value changes
QtCore.QObject.connect(
self.progressBar,
QtCore.SIGNAL("valueChanged(int)"),
self.repaint
)
QtCore.QMetaObject.connectSlotsByName(ProgressBarDialog)
def retranslateUi(self, ProgressBarDialog):
ProgressBarDialog.setWindowTitle("Please Wait")
def closeEvent(self, event, force=False):
if self.on_close is not None and not force:
self.on_close()
app = QtGui.QApplication(sys.argv)
filename = str(QtGui.QFileDialog.getSaveFileName(
None,
"Save as",
os.getcwd(),
"Data files: (*.dat)"
))
loop_mutex = thread.allocate_lock()
cancelled = False
can_quit = False
result = None
def cancel_download():
global cancelled
if can_quit:
return
if QtGui.QMessageBox.question(
None,
'Cancel Download',
"Are you sure you want to cancel the download?",
QtGui.QMessageBox.Yes | QtGui.QMessageBox.No,
QtGui.QMessageBox.No) == QtGui.QMessageBox.Yes:
with loop_mutex:
selected_device.cancelDownload()
cancelled = True
while not can_quit:
time.sleep(0.25)
form = ProgressBarDialog.Ui_ProgressBarDialog(cancel_download)
form.setWindowTitle("Please Wait")
form.progressBar.setMaximum(1000)
form.progressBar.setValue(0)
form.show()
def long_slow_loop(mutex, filename):
global can_quit, result
progress = 0
temp_binary_file = open(filename, "wb")
#The iterator below does the actual work of interacting with a
#hardware device, so I'm locking around the "for" line. I must
#not fetch more data from the device while a cancel command is
#in progress, and vice versa
mutex.acquire()
for data in ComplexIteratorThatInteractsWithHardwareDevice():
mutex.release()
temp_binary_file.write(datablock)
progress += 1
form.emit(QtCore.SIGNAL("updateProgress"), progress)
mutex.acquire()
if cancelled:
break
mutex.release()
result = not cancelled
temp_binary_file.close()
if cancelled:
os.unlink(filename)
#having set can_quit to True the following emission SHOULD
#cause the app to exit by closing the last top level window
can_quit = True
form.emit(QtCore.SIGNAL("closeDialog"), QtGui.QCloseEvent(), True)
thread.start_new_thread(do_dump, (loop_mutex, filename))
app.exec_()
if result == True:
QtGui.QMessageBox.information(None, 'Success', "Save to disk successful", QtGui.QMessageBox.Ok)
原来秘密是使用 QThread，它在线程退出时发出一些信号。 "finished" 或 "terminated" 取决于退出是正常还是异常。这是一些代码
import sys
import os
import time
from PyQt4 import QtCore, QtGui
class Ui_ProgressBarDialog(QtGui.QWidget):
def __init__(self, process, parent = None):
QtGui.QWidget.__init__(self, parent)
self.thread = process
self.setupUi(self)
self.center()
self.thread.start()
def center(self):
qr = self.frameGeometry()
cp = QtGui.QDesktopWidget().availableGeometry().center()
qr.moveCenter(cp)
self.move(qr.topLeft())
def setupUi(self, ProgressBarDialog):
ProgressBarDialog.setObjectName("ProgressBarDialog")
ProgressBarDialog.resize(400, 33)
self.verticalLayout = QtGui.QVBoxLayout(ProgressBarDialog)
self.verticalLayout.setObjectName("verticalLayout")
self.progressBar = QtGui.QProgressBar(ProgressBarDialog)
self.progressBar.setProperty("value", 0)
self.progressBar.setObjectName("progressBar")
self.verticalLayout.addWidget(self.progressBar)
self.retranslateUi(ProgressBarDialog)
#Close when the thread finishes (normally)
QtCore.QObject.connect(
self.thread,
QtCore.SIGNAL("finished()"),
self.close
)
#Close when the thread is terminated (exception, cancelled etc)
QtCore.QObject.connect(
self.thread,
QtCore.SIGNAL("terminated()"),
self.close
)
#Let the thread update the progress bar position
QtCore.QObject.connect(
self.thread,
QtCore.SIGNAL("updateProgress"),
self.progressBar.setValue
)
#Repaint when the progress bar value changes
QtCore.QObject.connect(
self.progressBar,
QtCore.SIGNAL("valueChanged(int)"),
ProgressBarDialog.repaint
)
QtCore.QMetaObject.connectSlotsByName(ProgressBarDialog)
def retranslateUi(self, ProgressBarDialog):
ProgressBarDialog.setWindowTitle("Please Wait")
def closeEvent(self, event):
if self.thread.exit_status == self.thread.RUNNING:
if QtGui.QMessageBox.question(None, 'Cancel Download', "Are you sure you want to cancel the download?", QtGui.QMessageBox.Yes | QtGui.QMessageBox.No, QtGui.QMessageBox.No) == QtGui.QMessageBox.Yes:
if self.thread.exit_status == self.thread.RUNNING:
self.thread.exiting = True
while self.thread.exiting:
time.sleep(0.25)
elif self.thread.exit_status == self.thread.SUCCESS:
self.thread.exit_status = self.thread.CANCELLED
else:
if self.thread.exit_status == self.thread.RUNNING:
event.ignore()
app = QtGui.QApplication(sys.argv)
filename = str(QtGui.QFileDialog.getSaveFileName(
None,
"Save as",
os.getcwd(),
"Data files: (*.dat)"
))
class DeviceDataStreamHandler(QtCore.QThread):
RUNNING = 1
SUCCESS = 0
FAILURE = -1
CANCELLED = -2
class CancelledError(Exception):
pass
def __init__(self, parent = None, **kwargs):
QtCore.QThread.__init__(self, parent)
self.exiting = False
self.exit_status = DeviceDataStreamHandler.RUNNING
self.device = device
self.filename = filename
def run(self):
progress = 0
try:
temp_binary_file = open(self.filename, "wb")
#getDataStream is an interator returing strings
for data in self.device.getDataStream():
temp_binary_file.write(data)
progress += 1
self.emit(QtCore.SIGNAL("updateProgress"), progress)
if self.exiting:
raise DeviceDataStreamHandler.CancelledError()
self.exit_status = DeviceDataStreamHandler.SUCCESS
except DeviceDataStreamHandler.CancelledError:
self.exit_status = DeviceDataStreamHandler.CANCELLED
self.device.cancelDownload()
except Exception as E:
self.exit_status = DeviceDataStreamHandler.FAILURE
self.error_details = str(E)
finally:
temp_binary_file.close()
if self.exit_status == DeviceDataStreamHandler.CANCELLED:
os.unlink(filename)
self.exiting = False
class HardwareDeviceObject(object):
def __init__(self):
#initialises comms with a hardware device
self.event_count = 0
self.capture = False
def startCapture(self):
self.capture = True
def cancelDownload():
self.capture = False
def read(self):
#returns a string sent from the device
time.sleep(1)
self.event_count += 1
return self.event_count
def getDataStream(self):
class DataStreamIterator(object):
def __init__(self, ds, max_capture_count = 100):
self.ds = ds
self.capture_count = 0
self.max_capture_count = max_capture_count
def __iter__(self):
return self
def next(self):
#return string received from device
if self.ds.capture and self.capture_count < self.max_capture_count:
self.capture_count += 1
return self.ds.read()
else:
raise StopIteration()
self.startCapture()
return DataStreamIterator(self)
capture = DeviceDataStreamHandler(device = HardwareDeviceObject(), filename = filename)
form = ProgressBarDialog.Ui_ProgressBarDialog(capture)
form.setWindowTitle("Dumping sessions")
form.progressBar.setMaximum(100) #expect 100 outputs from the device
form.progressBar.setValue(0)
form.show()
app.exec_()
if capture.exit_status == DeviceDataStreamHandler.SUCCESS:
QtGui.QMessageBox.information(None, 'Success', "Save to disk successful", QtGui.QMessageBox.Ok)
elif capture.exit_status == DeviceDataStreamHandler.FAILURE:
QtGui.QMessageBox.critical(None, 'Error interacting with device', "{}".format(capture.error_details), QtGui.QMessageBox.Ok)
我正在编写一个 PyQT4 (4.11) 程序，该程序执行一个长时间缓慢的任务，理想情况下需要一个进度条。如果我不使用线程、子classing 一个只包含一个QProgressBar 和一个布局的QWidget，该程序几乎可以完美运行。将这个子 class 实例化为 form，我可以调用 form.show() 将其显示在屏幕上，然后我的长慢循环可以通过调用 form.progressbar.setValue(progress) 来更新进度。这有两个问题：
如果用户尝试与 window 交互，他们会从 windows manager/OS 桌面进程收到 'not responding' 消息。这是因为事件没有被处理。
因为事件没有被处理，用户不能通过关闭 window.
来取消长的慢循环
所以我尝试在单独的线程中制作长而慢的循环 运行，使用信号更新进度条。我覆盖了我的 QWidget 的 closeEvent，以便它可以取消与硬件设备的交互（全部包装在互斥体中，因此设备通信不会不同步）。同样，这几乎可行。如果我取消，应用程序将退出。如果我让它完成 运行，我必须手动关闭 window（即单击关闭图标或按 alt-f4），即使我正在向 QWidget 发送关闭信号。正如您在下面的代码中看到的那样，有一些复杂情况，因为如果取消应用程序不能立即关闭，因为它必须等待一些硬件清理发生。这是我的代码的最小版本
import sys
import os
import time
from PyQt4 import QtCore, QtGui
class Ui_ProgressBarDialog(QtGui.QWidget):
def __init__(self, on_close=None):
QtGui.QWidget.__init__(self)
self.setupUi(self)
self.center()
#on_close is a function that is called to cancel
#the long slow loop
self.on_close = on_close
def center(self):
qr = self.frameGeometry()
cp = QtGui.QDesktopWidget().availableGeometry().center()
qr.moveCenter(cp)
self.move(qr.topLeft())
def setupUi(self, ProgressBarDialog):
ProgressBarDialog.setObjectName(_fromUtf8("ProgressBarDialog"))
ProgressBarDialog.resize(400, 33)
self.verticalLayout = QtGui.QVBoxLayout(ProgressBarDialog)
self.verticalLayout.setObjectName(_fromUtf8("verticalLayout"))
self.progressBar = QtGui.QProgressBar(ProgressBarDialog)
self.progressBar.setProperty("value", 0)
self.progressBar.setObjectName(_fromUtf8("progressBar"))
self.verticalLayout.addWidget(self.progressBar)
self.retranslateUi(ProgressBarDialog)
#This allows the long slow loop to update the progress bar
QtCore.QObject.connect(
self,
QtCore.SIGNAL("updateProgress"),
self.progressBar.setValue
)
#Catch the close event so we can interrupt the long slow loop
QtCore.QObject.connect(
self,
QtCore.SIGNAL("closeDialog"),
self.closeEvent
)
#Repaint the window when the progress bar's value changes
QtCore.QObject.connect(
self.progressBar,
QtCore.SIGNAL("valueChanged(int)"),
self.repaint
)
QtCore.QMetaObject.connectSlotsByName(ProgressBarDialog)
def retranslateUi(self, ProgressBarDialog):
ProgressBarDialog.setWindowTitle("Please Wait")
def closeEvent(self, event, force=False):
if self.on_close is not None and not force:
self.on_close()
app = QtGui.QApplication(sys.argv)
filename = str(QtGui.QFileDialog.getSaveFileName(
None,
"Save as",
os.getcwd(),
"Data files: (*.dat)"
))
loop_mutex = thread.allocate_lock()
cancelled = False
can_quit = False
result = None
def cancel_download():
global cancelled
if can_quit:
return
if QtGui.QMessageBox.question(
None,
'Cancel Download',
"Are you sure you want to cancel the download?",
QtGui.QMessageBox.Yes | QtGui.QMessageBox.No,
QtGui.QMessageBox.No) == QtGui.QMessageBox.Yes:
with loop_mutex:
selected_device.cancelDownload()
cancelled = True
while not can_quit:
time.sleep(0.25)
form = ProgressBarDialog.Ui_ProgressBarDialog(cancel_download)
form.setWindowTitle("Please Wait")
form.progressBar.setMaximum(1000)
form.progressBar.setValue(0)
form.show()
def long_slow_loop(mutex, filename):
global can_quit, result
progress = 0
temp_binary_file = open(filename, "wb")
#The iterator below does the actual work of interacting with a
#hardware device, so I'm locking around the "for" line. I must
#not fetch more data from the device while a cancel command is
#in progress, and vice versa
mutex.acquire()
for data in ComplexIteratorThatInteractsWithHardwareDevice():
mutex.release()
temp_binary_file.write(datablock)
progress += 1
form.emit(QtCore.SIGNAL("updateProgress"), progress)
mutex.acquire()
if cancelled:
break
mutex.release()
result = not cancelled
temp_binary_file.close()
if cancelled:
os.unlink(filename)
#having set can_quit to True the following emission SHOULD
#cause the app to exit by closing the last top level window
can_quit = True
form.emit(QtCore.SIGNAL("closeDialog"), QtGui.QCloseEvent(), True)
thread.start_new_thread(do_dump, (loop_mutex, filename))
app.exec_()
if result == True:
QtGui.QMessageBox.information(None, 'Success', "Save to disk successful", QtGui.QMessageBox.Ok)
原来秘密是使用 QThread，它在线程退出时发出一些信号。 "finished" 或 "terminated" 取决于退出是正常还是异常。这是一些代码
import sys
import os
import time
from PyQt4 import QtCore, QtGui
class Ui_ProgressBarDialog(QtGui.QWidget):
def __init__(self, process, parent = None):
QtGui.QWidget.__init__(self, parent)
self.thread = process
self.setupUi(self)
self.center()
self.thread.start()
def center(self):
qr = self.frameGeometry()
cp = QtGui.QDesktopWidget().availableGeometry().center()
qr.moveCenter(cp)
self.move(qr.topLeft())
def setupUi(self, ProgressBarDialog):
ProgressBarDialog.setObjectName("ProgressBarDialog")
ProgressBarDialog.resize(400, 33)
self.verticalLayout = QtGui.QVBoxLayout(ProgressBarDialog)
self.verticalLayout.setObjectName("verticalLayout")
self.progressBar = QtGui.QProgressBar(ProgressBarDialog)
self.progressBar.setProperty("value", 0)
self.progressBar.setObjectName("progressBar")
self.verticalLayout.addWidget(self.progressBar)
self.retranslateUi(ProgressBarDialog)
#Close when the thread finishes (normally)
QtCore.QObject.connect(
self.thread,
QtCore.SIGNAL("finished()"),
self.close
)
#Close when the thread is terminated (exception, cancelled etc)
QtCore.QObject.connect(
self.thread,
QtCore.SIGNAL("terminated()"),
self.close
)
#Let the thread update the progress bar position
QtCore.QObject.connect(
self.thread,
QtCore.SIGNAL("updateProgress"),
self.progressBar.setValue
)
#Repaint when the progress bar value changes
QtCore.QObject.connect(
self.progressBar,
QtCore.SIGNAL("valueChanged(int)"),
ProgressBarDialog.repaint
)
QtCore.QMetaObject.connectSlotsByName(ProgressBarDialog)
def retranslateUi(self, ProgressBarDialog):
ProgressBarDialog.setWindowTitle("Please Wait")
def closeEvent(self, event):
if self.thread.exit_status == self.thread.RUNNING:
if QtGui.QMessageBox.question(None, 'Cancel Download', "Are you sure you want to cancel the download?", QtGui.QMessageBox.Yes | QtGui.QMessageBox.No, QtGui.QMessageBox.No) == QtGui.QMessageBox.Yes:
if self.thread.exit_status == self.thread.RUNNING:
self.thread.exiting = True
while self.thread.exiting:
time.sleep(0.25)
elif self.thread.exit_status == self.thread.SUCCESS:
self.thread.exit_status = self.thread.CANCELLED
else:
if self.thread.exit_status == self.thread.RUNNING:
event.ignore()
app = QtGui.QApplication(sys.argv)
filename = str(QtGui.QFileDialog.getSaveFileName(
None,
"Save as",
os.getcwd(),
"Data files: (*.dat)"
))
class DeviceDataStreamHandler(QtCore.QThread):
RUNNING = 1
SUCCESS = 0
FAILURE = -1
CANCELLED = -2
class CancelledError(Exception):
pass
def __init__(self, parent = None, **kwargs):
QtCore.QThread.__init__(self, parent)
self.exiting = False
self.exit_status = DeviceDataStreamHandler.RUNNING
self.device = device
self.filename = filename
def run(self):
progress = 0
try:
temp_binary_file = open(self.filename, "wb")
#getDataStream is an interator returing strings
for data in self.device.getDataStream():
temp_binary_file.write(data)
progress += 1
self.emit(QtCore.SIGNAL("updateProgress"), progress)
if self.exiting:
raise DeviceDataStreamHandler.CancelledError()
self.exit_status = DeviceDataStreamHandler.SUCCESS
except DeviceDataStreamHandler.CancelledError:
self.exit_status = DeviceDataStreamHandler.CANCELLED
self.device.cancelDownload()
except Exception as E:
self.exit_status = DeviceDataStreamHandler.FAILURE
self.error_details = str(E)
finally:
temp_binary_file.close()
if self.exit_status == DeviceDataStreamHandler.CANCELLED:
os.unlink(filename)
self.exiting = False
class HardwareDeviceObject(object):
def __init__(self):
#initialises comms with a hardware device
self.event_count = 0
self.capture = False
def startCapture(self):
self.capture = True
def cancelDownload():
self.capture = False
def read(self):
#returns a string sent from the device
time.sleep(1)
self.event_count += 1
return self.event_count
def getDataStream(self):
class DataStreamIterator(object):
def __init__(self, ds, max_capture_count = 100):
self.ds = ds
self.capture_count = 0
self.max_capture_count = max_capture_count
def __iter__(self):
return self
def next(self):
#return string received from device
if self.ds.capture and self.capture_count < self.max_capture_count:
self.capture_count += 1
return self.ds.read()
else:
raise StopIteration()
self.startCapture()
return DataStreamIterator(self)
capture = DeviceDataStreamHandler(device = HardwareDeviceObject(), filename = filename)
form = ProgressBarDialog.Ui_ProgressBarDialog(capture)
form.setWindowTitle("Dumping sessions")
form.progressBar.setMaximum(100) #expect 100 outputs from the device
form.progressBar.setValue(0)
form.show()
app.exec_()
if capture.exit_status == DeviceDataStreamHandler.SUCCESS:
QtGui.QMessageBox.information(None, 'Success', "Save to disk successful", QtGui.QMessageBox.Ok)
elif capture.exit_status == DeviceDataStreamHandler.FAILURE:
QtGui.QMessageBox.critical(None, 'Error interacting with device', "{}".format(capture.error_details), QtGui.QMessageBox.Ok)