[Qgis-user] QGIS3 quits after PyQt Script 2 run

[Ludwig Kniprath]

Hi Julierme,

that's another and not a new problem, the button-widget and setFixedSize 
did not work before and even do not work in standalone-python outside QGis.

The reason is quite simple, we overlooked it before: double-underscores 
for the __init__-functions.


Here the running code, which does what You want (commented lines for 
QGis-usage, uncomment for standalone):


import sys
from PyQt5.QtCore import (QSize, Qt)
from PyQt5.QtWidgets import (QApplication,
                              QWidget,
                              QPushButton,
                              QMainWindow)


class MainWindow(QMainWindow):
     def __init__(self):
         super().__init__()
         self.setWindowTitle("My App")
         button = QPushButton("Press Me!")
         self.setCentralWidget(button)
         self.setFixedSize(QSize(400, 300))


#app = QApplication(sys.argv)
window = MainWindow()
window.show()
#app.exec()




hth

Ludwig




Am 17.08.23 um 04:14 schrieb 1520 gis:
> Hi Ludwig,
>
> Thank you very much for your reply. You're right, QGIS stopped 
> crashing, but now the button widget is not being carried out by the 
> application window and neither the methods are working properly like 
> the self.setFixedSize(QSize(400,300)). I am sending a window 
> screenshot in attachment.
>
> I appreciated your time and help.
>
> Kind regards
>
> Julierme
>
> On Wed, Aug 16, 2023 at 4:07 PM Ludwig Kniprath via QGIS-User 
> <qgis-user at lists.osgeo.org> wrote:
>
>     Hi Julierme,
>
>     I think Your problem is, that You try to create a new application
>     with "app = QApplication(sys.argv)" inside a running QGis, which
>     already is a running Qt-application.
>
>     Simplified code should perform without crash:
>
>     import sys
>     from PyQt5.QtCore import (QSize,Qt)
>     from PyQt5.QtWidgets import (QApplication, QWidget, QPushButton,
>     QMainWindow)
>
>     class MainWindow(QMainWindow):
>         def _init_(self):
>             super()._init_()
>             self.setWindowTitle("My App")
>             button = QPushButton("Press Me!")
>
>
>             self.setCentralWidget(button)
>             self.setFixedSize(QSize(400,300))
>
>     window = MainWindow()
>     window.show()
>
>
>     hth
>
>     Ludwig
>
>     Am 16.08.23 um 19:15 schrieb 1520 gis via QGIS-User:
>>     Hi all,
>>
>>     I wrote the PyQt script below and I am running it through QGIS3.
>>     When I run it for the first time after opening it in QGIS3, the
>>     application's window pops up smoothly. However, when I close the
>>     window and run the script, QGIS3 readily quits.  That may be
>>     something related to the event loop, but I'm unsure and don't
>>     know how to stop the QGIS3 shutdown for the subsequent runs.  Any
>>     hint on how to fix this issue will be very appreciated.
>>
>>     import sys
>>     from PyQt5.QtCore import (QSize,
>>                               Qt)
>>     from PyQt5.QtWidgets import (QApplication,
>>                                   QWidget,
>>                                   QPushButton,
>>                                   QMainWindow)
>>     class MainWindow(QMainWindow):
>>         def _init_(self):
>>             super()._init_()
>>             self.setWindowTitle("My App")
>>             button = QPushButton("Press Me!")
>>
>>
>>             self.setCentralWidget(button)
>>             self.setFixedSize(QSize(400,300))
>>     app = QApplication(sys.argv)
>>     window = MainWindow()
>>     window.show()
>>     app.exec()
>>     -- 
>>     ##########################################
>>     *Julierme G Pinheiro*
>>     *SDI Expert & Geoprocessing Specialist*
>>     Phone: +55 61 99994-3569
>>     Website: GIS
>>     <https://www.udemy.com/course/qgis-server-para-iniciantes-instalacao-e-configuracao/>
>>
>>     _______________________________________________
>>     QGIS-User mailing list
>>     QGIS-User at lists.osgeo.org
>>     List info:https://lists.osgeo.org/mailman/listinfo/qgis-user
>>     Unsubscribe:https://lists.osgeo.org/mailman/listinfo/qgis-user
>     _______________________________________________
>     QGIS-User mailing list
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>
>
>
> -- 
> ##########################################
> *Julierme G Pinheiro*
> *SDI Expert & Geoprocessing Specialist*
> Phone: +55 61 99994-3569
> Website: GIS 
> <https://www.udemy.com/course/qgis-server-para-iniciantes-instalacao-e-configuracao/>
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