问题背景:
我是PyQT4的新手。我正在用它开发一个程序,我正在进行网络抓取以将数据输入到我的程序中。当信息下载时,我的GUI锁定。我想在一个单独的后台线程中调用这个函数,也许可以使用QThread,但我很难理解QThread、一般的Qt以及插槽/信号通信方式。
我读过关于制作一个通用工作线程的文章,该线程将调用传递给它的任何函数。我不知道如何在我的主文件中实现它,以便我可以将函数作为后台进程运行。如果可以显示任何示例代码,请详细解释每一行,因为我不理解这个过程。
问题:
- 在函数运行时,如何防止GUI冻结
- 如何使用后台线程来运行类中的函数
代码:
我的ui是从Qt4Designer创建的外部文件加载的。
Github 上的完整文件
class Ui_MainWindow(object):
def setupUi(self, MainWindow):
MainWindow.setObjectName(_fromUtf8("MainWindow"))
main.py(主文件)
def connections():
# If button is clicked, call summary(), which web scrapes
# for data. This could take 5-30 seconds, this freezes UI.
ui.btnRefreshSummary.clicked.connect(lambda: summary())
# Refresh items in gui
def refresh_ui():
if summary_data != []:
ui.valWatching.setText(summary_data[0])
ui.valBidding.setText(summary_data[1])
ui.valWon.setText(summary_data[2])
ui.valNotWon.setText(summary_data[3])
ui.valPurchases.setText(summary_data[4])
ui.valInvoices.setText(summary_data[5])
def login():
# Scrape website and login while in background;
# This locks up GUI until it completes.
# Pretend this sleep command is the time it takes to login
time.sleep(5) # <-This would lock it up for 5 seconds
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
MainWindow = QtGui.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
connections()
# Load credentials from file.
with open('login.txt') as f:
credentials = f.readline().strip().split(':')
f.closed
# Login, download summary, then refresh the UI.
b = Biddergy()
b.login(credentials[0],credentials[1])
summary_data = b.summary()
b.logout()
refresh_ui()
sys.exit(app.exec_())
从示例代码中不清楚为什么connections()
会阻塞(给定它包含的代码),或者为什么login()
不应该阻止(给定登录对话框通常是这样做的)。但是无论如何,您的示例中的worker类可以转换为QThread
,如下所示:
class Worker(QThread):
intReady = pyqtSignal(int)
def run(self):
for i in range(1, 10):
time.sleep(1)
self.intReady.emit(i)
然后它可以这样使用:
# connections()
# login()
def slot(arg='finished'): print(arg)
thread = Worker()
thread.intReady.connect(slot)
thread.finished.connect(slot)
thread.start()
还有许多其他方法可以实现同样的目的,但哪种方法最合适,以及如何实际实现,取决于应用程序的工作细节。
有了这些更新的代码,我终于可以在后台启动我的函数了。现在开始学习如何使我的后台线程与主UI线程进行通信。非常感谢@ekhumuro对我的耐心。
#!/usr/bin/env python3
from PySide import QtGui, QtCore
from PySide.QtCore import QThread, QObject, Signal, Slot
from main_gui import Ui_MainWindow # my UI from Qt4 Designer(pyside-uic)
from Scrapers import Biddergy # My own class
import sys
import queue
class BiddergyWrapper(QThread):
def __init__(self, q, loop_time=1.0/60):
self.q = q
self.timeout = loop_time
super(BiddergyWrapper, self).__init__()
def onThread(self, function, *args, **kwargs):
self.q.put((function, args, kwargs))
def run(self):
while True:
try:
function, args, kwargs = self.q.get(timeout=self.timeout)
function(*args, **kwargs)
except queue.Empty:
self.idle()
def idle(self):
pass
def _summary(self):
b.summary()
def summary(self):
self.onThread(self._summary)
def _login(self):
b.login()
def login(self):
self.onThread(self._login())
if __name__ == "__main__":
app = QtGui.QApplication(sys.argv)
MainWindow = QtGui.QMainWindow()
ui = Ui_MainWindow()
ui.setupUi(MainWindow)
MainWindow.show()
ui.btnRefreshSummary.clicked.connect(lambda: bw.summary())
# Load credentials from file.
with open('login.txt') as f:
credentials = f.readline().strip().split(':')
# Login, download summary, then refresh the UI.
b = Biddergy(credentials[0], credentials[1])
request_queue = queue.Queue()
bw = BiddergyWrapper(request_queue)
bw.start()
# Run QApplication
app.exec_()
# Begin "Graceful stop?"
bw.quit()
b.logout()
sys.exit()