QtGui.QProgressBar
A progress bar is a widget that is used when we process lengthy tasks. It is animated so that the user knows that the task is progressing. The QtGui.QProgressBar widget provides a horizontal or vertical progress bar in PyQt4 toolkit. The programmer can set the minimum and maximum value for the progress bar. The default values are 0 and 99.
#!/usr/bin/python
# -*- coding: utf-8 -*- """
ZetCode PyQt4 tutorial This example shows a QtGui.QProgressBar widget. author: Jan Bodnar
website: zetcode.com
last edited: September 2011
""" import sys
from PyQt4 import QtGui, QtCore class Example(QtGui.QWidget): def __init__(self):
super(Example, self).__init__() self.initUI() def initUI(self): self.pbar = QtGui.QProgressBar(self)
self.pbar.setGeometry(30, 40, 200, 25) self.btn = QtGui.QPushButton('Start', self)
self.btn.move(40, 80)
self.btn.clicked.connect(self.doAction) self.timer = QtCore.QBasicTimer()
self.step = 0 self.setGeometry(300, 300, 280, 170)
self.setWindowTitle('QtGui.QProgressBar')
self.show() def timerEvent(self, e): if self.step >= 100: self.timer.stop()
self.btn.setText('Finished')
return self.step = self.step + 1
self.pbar.setValue(self.step) def doAction(self): if self.timer.isActive():
self.timer.stop()
self.btn.setText('Start') else:
self.timer.start(100, self)
self.btn.setText('Stop') def main(): app = QtGui.QApplication(sys.argv)
ex = Example()
sys.exit(app.exec_()) if __name__ == '__main__':
main()
In our example we have a horizontal progress bar and a push button. The push button starts and stops the progress bar.
self.pbar = QtGui.QProgressBar(self)
This is a QtGui.QProgressBar constructor.
self.timer = QtCore.QBasicTimer()
To activate the progress bar, we use a timer object.
self.timer.start(100, self)
To launch a timer event, we call its start() method. This method has two parameters: the timeout and the object which will receive the events.
def timerEvent(self, e):
if self.step >= 100:
self.timer.stop()
self.btn.setText('Finished')
return
self.step = self.step + 1
self.pbar.setValue(self.step)
Each QtCore.QObject and its descendants have a timerEvent() event handler. In order to react to timer events, we reimplement the event handler.
def doAction(self):
if self.timer.isActive():
self.timer.stop()
self.btn.setText('Start')
else:
self.timer.start(100, self)
self.btn.setText('Stop')
Inside the doAction() method, we start and stop the timer.
Figure: QtGui.QProgressBar
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