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#!/usr/bin/env python
# -*- coding: utf-8 -*-
from PyQt4 import QtGui, QtCore
import time
import sys
import random
class WorkerThread(QtCore.QThread):
# Worker Thread
# We define some signals to connect to. I choose to implement them in the
# worker thread, but we could also implement them in the main thread
# I use one signal to realy the progression, another to notify failures.
advanced = QtCore.pyqtSignal(int)
error_raised = QtCore.pyqtSignal(str)
def __init__(self, app, steps, raise_error=False):
# app holds a reference to the parent, so the thread is destroyed if
# application closes
# steps is some value for our demo task
# raise_error is also some value to test raising an error in a thread
super().__init__(app)
# Do init steps here
self.steps = steps
self.raise_error = raise_error
def run(self):
# A stupid function to demonstrate something that takes time.
# The handling of the progress bar is also a little but rough, as
# we could better define minimum and maximum and not convert into
# percentages. But as long operations do not always want to report
# at each iteration (this takes computation time), there may be an algorithm
# here anyway.
try:
for i in range(self.steps):
time.sleep(1)
# Signal advancement to connected slots
self.advanced.emit(i*100/self.steps)
self.advanced.emit(100)
if self.raise_error:
raise RuntimeError("Hey you! Don't")
# Demonstrate how one could handle failures in a thread
except RuntimeError as e:
self.error_raised.emit(str(e))
class SampleApp(QtGui.QApplication):
# Main application
def __init__(self):
super().__init__(sys.argv)
# Define widgets
self.mainWindow = QtGui.QWidget()
self.prProgress1 = QtGui.QProgressBar()
self.prProgress2 = QtGui.QProgressBar()
self.vbProgress = QtGui.QVBoxLayout()
self.btnQuit = QtGui.QPushButton("Close")
self.btnStart = QtGui.QPushButton("Start")
self.btnSurprise = QtGui.QPushButton(":)")
self.vbButtons = QtGui.QVBoxLayout()
self.hbBox = QtGui.QHBoxLayout()
# Setup layout
self.vbProgress.addWidget(self.prProgress1)
self.vbProgress.addWidget(self.prProgress2)
self.vbButtons.addWidget(self.btnStart)
self.vbButtons.addWidget(self.btnSurprise)
self.hbBox.addLayout(self.vbButtons)
self.hbBox.addLayout(self.vbProgress)
self.hbBox.addWidget(self.btnQuit)
self.mainWindow.setLayout(self.hbBox)
# Configure widgets
self.mainWindow.resize(500, 0)
self.prProgress1.setMinimum(0)
self.prProgress2.setMinimum(0)
self.prProgress1.setMaximum(100)
self.prProgress2.setMaximum(100)
# Instanciate workers. This may be done elsewhere as needed, not
# specifically in init, and maybe not handled as separate attributes, but
# maybe a queue or a list
self.worker1 = WorkerThread(self, 10, False)
self.worker2 = WorkerThread(self, 15, True)
# Connect signals: progression, error and finished events
self.worker1.advanced.connect(self.prProgress1.setValue)
self.worker2.advanced.connect(self.prProgress2.setValue)
self.worker1.error_raised.connect(self.onError)
self.worker2.error_raised.connect(self.onError)
self.worker1.finished.connect(self.workerFinished)
self.worker2.finished.connect(self.workerFinished)
# Connect signals of widgets
self.btnQuit.clicked.connect(self.quit)
self.btnStart.clicked.connect(self.startWorkers)
self.btnSurprise.clicked.connect(self.surprise)
def run(self):
# Main loop
self.mainWindow.show()
return self.exec_()
def startWorkers(self):
# Start the workers
self.btnQuit.setEnabled(False)
self.btnStart.setEnabled(False)
self.worker1.start()
self.worker2.start()
def onError(self, error_msg):
# If a thread had an error, display a dialog box to the user
msgBox = QtGui.QMessageBox()
msgBox.setText(error_msg)
msgBox.exec_()
def workerFinished(self):
# When a thread notifies it has finished, check if we can enable the buttons
if self.worker1.isFinished() and self.worker2.isFinished():
self.btnQuit.setEnabled(True)
self.btnStart.setEnabled(True)
def surprise(self):
# Demonstrates that the UI is still responsive meanwhile
self.btnSurprise.setText(random.choice([
":S", ":(", ":D", ":P", ":O", ";)"
]))
def main():
app = SampleApp()
return app.run()
if __name__ == '__main__':
main()
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