Question

I have some code like that:

class MyApp(Ui_MainWindow):
    def __init__(self):
        pass

    def setupUi(self, *args):
        super(MyApp, self).setupUi(*args)
        QtCore.QObject.connect(self.pushButton, QtCore.SIGNAL(_fromUtf8("clicked()")), self.doCheck)

    def doCheck(self):
        self.pushButton.setText(QtGui.QApplication.translate("MainWindow", "Checking...", None, QtGui.QApplication.UnicodeUTF8))
        # Code to do real checking here... (it's a network app)
        # When check done, display result in a "QTextBrowser" 
        # ....
        # Change text of Button to "Done!"
        self.pushButton.setText(QtGui.QApplication.translate("MainWindow", "Done!", None, QtGui.QApplication.UnicodeUTF8))

But the result not as I expect.
My app do network checking and display result ok, but the button did not change text to “Checking…” when the check begin; it’s only change text to “Done!” when everything is finished!

Answer 1

After changing button label you should run QApplication::processEvents() to update UI with new label.

Notice that your UI will be freezed while long task is running. To avoid this you should sometimes call QApplication::processEvents() during long operation or run this operation in separate QThread.