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PyQt gui update

I am trying to update text in a Qt GUI object through QThreadin PyQt, but I just get an error message QPixmap: It is not safe to use pixmaps outside the GUI thread, after which it crashes. I would really appreciate any help, thanks.

class MainWindow(QMainWindow, Ui_MainWindow):

    def __init__(self, parent = None):
        QMainWindow.__init__(self, parent)
        self.setupUi(self)
        self.output = Output()

    def __del__ (self):
        self.ui = None

    @pyqtSignature("")
    def on_goBtn_released(self):
        threadnum = 1
        #start threads
        for x in xrange(threadnum):
            thread = TheThread() 
            thread.start()


class Output(QWidget, Ui_Output):

    def __init__(self, parent = None):
        QWidget.__init__(self, parent)
        self.setupUi(self)
        self.ui = Ui_Output
        self.show()

    def main(self):
        self.textBrowser.append("sdgsdgsgsg dsgdsg dsgds gsdf")



class TheThread(QtCore.QThread):

    trigger = pyqtSignal()

    def __init__(self):
        QtCore.QThread.__init__(self)

    def __del__(self):
        self.wait()

    def run(self):
        self.trigger.connect(Output().main())
        self.trigger.emit()
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self.trigger.connect(Output().main())

This line is problematic. You create a class in a stream that looks like a widget. This is not true. You should not use GUI elements in another thread. All GUI-related code must run in the same thread with the event loop.

The above line is also incorrect in terms of design. You emit a custom signal from your stream, and this is a good way. But the object for processing this signal should be the one that owns / creates the stream, namely yourMainWindow

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:

import sys
from PyQt4 import QtGui, QtCore
import time
import random


class MyThread(QtCore.QThread):
    trigger = QtCore.pyqtSignal(int)

    def __init__(self, parent=None):
        super(MyThread, self).__init__(parent)

    def setup(self, thread_no):
        self.thread_no = thread_no

    def run(self):
        time.sleep(random.random()*5)  # random sleep to imitate working
        self.trigger.emit(self.thread_no)


class Main(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(Main, self).__init__(parent)
        self.text_area = QtGui.QTextBrowser()
        self.thread_button = QtGui.QPushButton('Start threads')
        self.thread_button.clicked.connect(self.start_threads)

        central_widget = QtGui.QWidget()
        central_layout = QtGui.QHBoxLayout()
        central_layout.addWidget(self.text_area)
        central_layout.addWidget(self.thread_button)
        central_widget.setLayout(central_layout)
        self.setCentralWidget(central_widget)

    def start_threads(self):
        self.threads = []              # this will keep a reference to threads
        for i in range(10):
            thread = MyThread(self)    # create a thread
            thread.trigger.connect(self.update_text)  # connect to it signal
            thread.setup(i)            # just setting up a parameter
            thread.start()             # start the thread
            self.threads.append(thread) # keep a reference

    def update_text(self, thread_no):
        self.text_area.append('thread # %d finished' % thread_no)

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)

    mainwindow = Main()
    mainwindow.show()

    sys.exit(app.exec_())
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