QObject::setParent: Cannot set parent, new parent is in a different thread Segmentation fault

Bisrat

i am working on new project with combines voice recognition and GUI in which the users will interact with GUI by using their voice. and i have 3 main windows,.

Main window => which is actual GUI for user. shown until users minimize it.
Mini window => which stays at top to show user what he said. always shown.
Text input window => which is user for user to enter and edit long paragraphs and text inputs using voice. shown when user needs to insert data and then back to hidden.

also i have a QThread which will give a text input form speech recognition to MainThread. so the problem is when i try to show the text input window and put convert text and hide it cause this error.

QObject::setParent: Cannot set parent, new parent is in a different thread
Segmentation fault

JKSH

@Bisrat said in QObject::setParent: Cannot set parent, new parent is in a different thread Segmentation fault:

can you edit the sample code i lost in here.

Remove Qt.DirectConnection

EDIT: Ah I just realized you meant edit your forum post

JKSH

Hi, and welcome!

@Bisrat said in QObject::setParent: Cannot set parent, new parent is in a different thread Segmentation fault:

also i have a QThread which will give a text input form speech recognition to MainThread. so the problem is when i try to show the text input window and put convert text and hide it cause this error.

You must only call GUI class methods from the GUI (main) thread. You are not allowed to call the methods from the other thread.

Instead, emit a signal to pass the text from your other thread to the GUI thread and then call the methods there.

Bisrat

I understand that but as far as i see i didn't call gui methods from other thread there is sample of my code where error raised

# IMPORT / GUI AND MODULES AND WIDGETS

input_module = InputModule()

class MainWindow(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)

        # SET AS GLOBAL WIDGETS
        global input_module
        self.mini_window = MiniWindow()
        self.text_window = TextInputWindows()
        self.text_window.hide()
        self.worker_thread = WorkerThread(_input_module=input_module)
        self.worker_thread.start()
        self.connect(self.worker_thread, SIGNAL("thread_done(QString)"), self.thread_done, Qt.DirectConnection)

        # SHOW APP
        self.show()

    def thread_done(self, cmd):
        self.mini_window.set_text(cmd)
        if cmd == "maximize":
            self.maximize()
        elif cmd == "minimize" or cmd == "close":
            self.hide()
        elif cmd == "open window":
            self.show()
        elif cmd == "go to gmail":
            self.click_email_btn()
            self.click_youtube_btn()
        elif self.current_module == "News":
            if cmd == "input":
                print(threading.currentThread())
                final_text = self.text_input()
                if final_text is not None:
                    self.ui.NewsSearchText.setText(final_text)
            if cmd == "search":
                self.ui.NewsSearchBtn.click()

    def text_input(self):
        print(threading.currentThread())
        self.text_window.show()
        while True:
            _cmd = input_module.take_final_input().lower()
            if _cmd == "add":
                self.text_window.set_whole_word_text(self.text_window.get_word_text())
            elif _cmd == "clear":
                self.text_window.clear()
            elif _cmd == "go back":
                final_text = self.text_window.get_whole_word_text()
                self.text_window.clear()
                self.text_window.hide()
                return final_text
            else:
                self.text_window.set_word_text(_cmd)

class MiniWindow(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)
        self.ui = Ui_MiniVAHDP()
        self.ui.setupUi(self)
        self.setWindowFlags(
            Qt.Tool | Qt.FramelessWindowHint | Qt.Window | Qt.CustomizeWindowHint | Qt.WindowStaysOnTopHint)
        self.move(0, 0)
        self.show()

    def set_text(self, text):
        self.ui.MiniLabel.setText(text)

    def set_module(self, text):
        self.ui.ModuleLabel.setText(text)


class TextInputWindows(QMainWindow):
    socketSignal = QtCore.Signal(object)

    def __init__(self):
        QMainWindow.__init__(self)
        self.ui = Ui_TextInput()
        self.ui.setupUi(self)
        self.setWindowFlags(Qt.FramelessWindowHint | Qt.CustomizeWindowHint | Qt.WindowStaysOnTopHint)
        self.show()

    def set_word_text(self, text):
        self.ui.WordText.setText(text)

    def set_whole_word_text(self, text):
        self.ui.WholeWordText.appendPlainText(text)

    def clear(self):
        self.ui.WholeWordText.setPlainText("")
        self.ui.WordText.setText("")

    def get_word_text(self):
        return self.ui.WordText.text()

    def get_whole_word_text(self):
        return self.ui.WholeWordText.toPlainText()


class WorkerThread(QThread):
    def __init__(self, parent=None, _input_module=None):
        super(WorkerThread, self).__init__(parent)
        self.input_module = _input_module
        self.cmd = None
        self.sleep = False

    def run(self):
        while True:
            self.cmd = self.input_module.take_final_input().lower()
            if self.cmd == "wake up":
                self.sleep = False
            elif self.cmd == "sleep":
                self.sleep = True
            elif not self.sleep:
                self.emit(SIGNAL("thread_done(QString)"), self.cmd)


if __name__ == "__main__":
    app = QApplication(sys.argv)
    app.setWindowIcon(QIcon("icon.ico"))
    window = MainWindow()
    print(threading.currentThread())
    app.exec()


# error raised on  final_text = self.text_input()

jeremy_k

@Bisrat said in QObject::setParent: Cannot set parent, new parent is in a different thread Segmentation fault:

I understand that but as far as i see i didn't call gui methods from other thread there is sample of my code where error raised

The formatting of the code went awry, and unfortunately formatting in python is everything. That said, this looks like a problem:

class MainWindow(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)
        [...]
        self.connect(self.worker_thread, SIGNAL("thread_done(QString)"), self.thread_done, Qt.DirectConnection)

The direct connection means that the slot will be run in the thread that emits the signal. The slot appears to be defined in a QWidget derived class, and perform gui operations, and the signal appears to be emitted from a non-gui thread.

Bisrat

@jeremy_k Thanks for response.
can you edit the sample code i lost in here.

JKSH

@Bisrat said in QObject::setParent: Cannot set parent, new parent is in a different thread Segmentation fault:

can you edit the sample code i lost in here.

Remove Qt.DirectConnection

EDIT: Ah I just realized you meant edit your forum post

jeremy_k

@Bisrat I don't have the ability to edit other users' posts. You can by clicking the column of three dots to the right of the bottom of your post, and then choosing edit.

Bisrat

Thanks it worked fine