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QtCreator's UI is not applied to the window, it's always empty (Qt for Python)

I have a fresh QtCreator installation, and I set it up to run using a fresh install of Python3.8 on which I pip-installed both pyside2 and pyside6.
When I create a new Qt for Python - Window (UI file) application, whatever I do to the UI file the window always shows up empty and with the default size when I run the app.
I've tried with a QDialog, QMainApplication, using Pyside2 or Pyside6, I've checked that it was correctly loading the UI (and the right one) - no dice. It just won't update, and appears not to have any reason not to.
Default code for completeness:
# This Python file uses the following encoding: utf-8
import os
from pathlib import Path
import sys
from PySide2.QtWidgets import QApplication, QDialog
from PySide2.QtCore import QFile
from PySide2.QtUiTools import QUiLoader
class Dialog(QDialog):
def __init__(self):
super(Dialog, self).__init__()
self.load_ui()
def load_ui(self):
loader = QUiLoader()
path = os.fspath(Path(__file__).resolve().parent / "form.ui")
ui_file = QFile(path)
ui_file.open(QFile.ReadOnly)
loader.load(ui_file, self)
ui_file.close()
if __name__ == "__main__":
app = QApplication([])
widget = Dialog()
widget.show()
sys.exit(app.exec_())
(In the UI I just drag-dropped a button right in the middle and saved the file)
Am I forgetting something fundamental? I'm only used to programming in C++ using QtCreator.

I was expecting this to work right out of the box, but it's not.
This only dynamically load the UI as a new widget, with this custom class as a parent.
If I want signals and slots to work, the only thing I've found was to add a custom build step:
Command: <path to pyside6 install, use pip show to know where>\uic.exe
Arguments: <filename of the .ui file> -o <the python translation .py
which will serve as baseclass> -g python
Working directory: [your project dir]
Then signals and slots need to be connected manually, so QtCreator really only enables you to draw the user interface but all the logic still needs to be done by hand. Component variables are normally named after their UI name, but you can see for yourself in the baseclass file. This is a big step back from how QtCreator is used in C++ ("go to slot" will not work).
Code to use:
import sys
from PySide6.QtWidgets import QApplication, QMainWindow
from PySide6.QtCore import QFile
from PySide6.QtUiTools import QUiLoader
from YourGenPyFileName import Ui_YourUIName
class MainWindow(QMainWindow, Ui_YourUIName):
def __init__(self):
super(MainWindow, self).__init__()
self.setupUi(self)
if __name__ == "__main__":
app = QApplication([])
widget = MainWindow()
widget.show()
sys.exit(app.exec_())

QAxWidget glitches when resizing GUI window

I am currently exploring the possibilities of displaying and working with PowerPoint presentations in a GUI using PyQt5/PyQt6 and Python. For that I found the most promising solution to be using a QAxWidget. Loading and displaying the pptx-file works fine, but unfortunately I noticed glitches when resizing the window of the GUI.
As a minimal example I used the following tutorial from the official Qt docs:
https://doc.qt.io/qtforpython/examples/example_axcontainer__axviewer.html?highlight=qaxwidget
After the QAxWidget()-initialization i just added the following line:
self.axWidget.setControl(r"C:\path\to\file\presentation.pptx")
Full code (taken from: https://doc.qt.io/qtforpython/examples/example_axcontainer__axviewer.html?highlight=qaxwidget):
# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
"""PySide6 Active Qt Viewer example"""
import sys
from PyQt5.QtWidgets import qApp
from PySide6.QtAxContainer import QAxSelect, QAxWidget
from PySide6.QtGui import QAction
from PySide6.QtWidgets import (QApplication, QDialog,
QMainWindow, QMessageBox, QToolBar)
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
toolBar = QToolBar()
self.addToolBar(toolBar)
fileMenu = self.menuBar().addMenu("&File")
loadAction = QAction("Load...", self, shortcut="Ctrl+L", triggered=self.load)
fileMenu.addAction(loadAction)
toolBar.addAction(loadAction)
exitAction = QAction("E&xit", self, shortcut="Ctrl+Q", triggered=self.close)
fileMenu.addAction(exitAction)
aboutMenu = self.menuBar().addMenu("&About")
aboutQtAct = QAction("About &Qt", self, triggered=qApp.aboutQt)
aboutMenu.addAction(aboutQtAct)
self.axWidget = QAxWidget()
self.axWidget.setControl(r"C:\path\to\file\presentation.pptx")
self.setCentralWidget(self.axWidget)
def load(self):
axSelect = QAxSelect(self)
if axSelect.exec() == QDialog.Accepted:
clsid = axSelect.clsid()
if not self.axWidget.setControl(clsid):
QMessageBox.warning(self, "AxViewer", f"Unable to load {clsid}.")
if __name__ == '__main__':
app = QApplication(sys.argv)
mainWin = MainWindow()
availableGeometry = mainWin.screen().availableGeometry()
mainWin.resize(availableGeometry.width() / 3, availableGeometry.height() / 2)
mainWin.show()
sys.exit(app.exec())
When resizing the window of the GUI, there appear some glitches underneath:
An animation that shows the result while resizing:
Unfortunately I haven't found many resources I could use where a QAxWidget is used in combination with Python to figure this out myself. That's why I'm here to ask if anyone out there might have a solution for getting rid of those glitches.

I got rid of the glitches by installing an event filter to the QAxWidget using self.axWidget.installEventFilter(self).
This will call the eventFilter()-method of the QMainWindow which I set up like this: (ReportDefinitionTool is the subclass of QMainWindow here.)
def eventFilter(self, widget: QWidget, event: QEvent):
if event.type() == QEvent.Resize and widget is self.pptx_axwidget:
self.pptx_axwidget.setFixedHeight(int(self.pptx_axwidget.width() / 16 * 9))
return super(ReportDefinitionTool, self).eventFilter(widget, event)
Since the PowerPoint-presentation is displayed in a 16:9 format, this will make sure the QAxWidget does only occupy this space. The glitchy space from the initial question came from the unused space of the QAxWidget.

Image copied to clipboard doesn't persist on Linux

I'm trying to save an image to the system clipboard, so I wrote some code like this:
#!/usr/bin/python3
from PyQt5.Qt import QApplication
from PyQt5.QtWidgets import QWidget, QPushButton
from PyQt5.Qt import QImage
import sys
class MyWidget(QWidget):
def __init__(self):
super(MyWidget, self).__init__()
self.button = QPushButton(self)
self.button.clicked.connect(self.copyPicToClip)
def copyPicToClip(self):
image = QImage('./test.jpg')
QApplication.clipboard().setImage(image)
self.close()
if __name__ == '__main__':
a = QApplication(sys.argv)
myW = MyWidget()
myW.show()
a.exec()
Sadly, I found it doesn't work at all. Then I tried to find a solution. The first thing I tried was this:
def copyPicToClip(self):
image = QImage('./test.jpg')
QApplication.clipboard().setImage(image)
# self.close()
After this, I just found that it worked, but the window does not close automatically.
Then I tried with copying text:
#!/usr/bin/python3
from PyQt5.Qt import QApplication, QClipboard
from PyQt5.QtWidgets import QWidget, QPushButton
from PyQt5.Qt import QImage
import sys
class MyWidget(QWidget):
def __init__(self):
super(MyWidget, self).__init__()
self.button = QPushButton(self)
self.button.clicked.connect(self.copyPicToClip)
QApplication.clipboard().dataChanged.connect(self.testFunc)
def copyPicToClip(self):
image = QImage('./test.jpg')
QApplication.clipboard().setImage(image)
def testFunc(self):
print('Here')
self.close()
if __name__ == '__main__':
a = QApplication(sys.argv)
myW = MyWidget()
myW.show()
a.exec()
Sadly, it failed again.
So, it seems that if I close the application to early, the image won't be saved to the clipboard. But I want to close it after copying the image to the clipboard.
Any suggestions?
(PyQt5, ubuntu 16.10, if helps).

Unfortunately for you, this is "normal" behaviour on Linux. By default, clipboard data is not persisted when an application closes. The usual work-around for this problem is to install a clipboard manager. For Ubuntu, see this wiki article for more details:
Ubuntu Wiki: Clipboard Persistence
(NB: I have not actually tested any of the suggested solutions myself, so I don't know whether any of them will work with PyQt).
The basic problem is that on Linux, the clipboard only stores a reference to the underlying data. This is very efficient in terms of storage, because the data is only copied when the client program actually requests it. But of course if the source application closes, the reference will be invalidated, and the clipboard will become empty.

How to make a window that occupies the full screen without maximising?

I'm writing in python using Qt
I want to create the application window (with decorations) to occupy the full screen size. Currently this is the code I have:
avGeom = QtGui.QDesktopWidget().availableGeometry()
self.setGeometry(avGeom)
the problem is that it ignores window decorations so the frame is larger... I googled and what not, found this:
http://harmattan-dev.nokia.com/docs/library/html/qt4/application-windows.html#window-geometry
which seems to indicate I need to set the frameGeometry to the avGeom however I haven't found a way to do that. Also, in the comments in the above link it says what I'm after may not be even possible as the programme can't set the frameGeometry before running... If that is the case I just want confirmation that my problem is not solvable.
EDIT:
So I played around with the code a bit and this gives what I want... however the number 24 is basically through trial and error until the window title is visible.... I want some better way to do this... which is window manager independent..
avGeom = QtGui.QDesktopWidget().availableGeometry()
avGeom.setTop(24)
self.setGeometry(avGeom)
Now I can do what I want but purely out of trial and error
Running Ubuntu, using Spyder as an IDE
thanks

Use QtGui.QApplication().desktop().availableGeometry() for the size of the window:
#!/usr/bin/env python
#-*- coding:utf-8 -*-
from PyQt4 import QtGui, QtCore
class MyWindow(QtGui.QWidget):
def __init__(self, parent=None):
super(MyWindow, self).__init__(parent)
self.pushButtonClose = QtGui.QPushButton(self)
self.pushButtonClose.setText("Close")
self.pushButtonClose.clicked.connect(self.on_pushButtonClose_clicked)
self.layoutVertical = QtGui.QVBoxLayout(self)
self.layoutVertical.addWidget(self.pushButtonClose)
titleBarHeight = self.style().pixelMetric(
QtGui.QStyle.PM_TitleBarHeight,
QtGui.QStyleOptionTitleBar(),
self
)
geometry = app.desktop().availableGeometry()
geometry.setHeight(geometry.height() - (titleBarHeight*2))
self.setGeometry(geometry)
#QtCore.pyqtSlot()
def on_pushButtonClose_clicked(self):
QtGui.QApplication.instance().quit()
if __name__ == "__main__":
import sys
app = QtGui.QApplication(sys.argv)
app.setApplicationName('MyWindow')
main = MyWindow()
main.show()
sys.exit(app.exec_())

I've always found inheritting from the QMainWindow class to be particularly useful. Like this:
import sys
from PySide.QtGui import *
from PySide.QtCore import *
class Some_APP(QMainWindow):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
### this line here is what you'd be looking for
self.setWindowState(Qt.WindowMaximized)
###
self.show()
def main():
app = QApplication(sys.argv)
some_app = Some_APP()
sys.exit(app.exec_())
if __name__ == "__main__":
main()

How to connect a signal from the controller in PyQt4? (iOS like MVC structure in PyQt4)

Why doesn't the following example work?
from PyQt4 import QtGui
import sys
class TestView(QtGui.QWidget):
def __init__(self):
super(TestView, self).__init__()
self.initUI()
def initUI(self):
self.btn = QtGui.QPushButton('Button', self)
self.btn.resize(self.btn.sizeHint())
self.btn.move(50, 50)
class TestViewController():
def __init__(self, view):
view.btn.clicked.connect(self.buttonClicked)
view.show()
def buttonClicked(self):
print 'clicked'
def main():
app = QtGui.QApplication(sys.argv)
view = TestView()
TestViewController(view)
app.exec_()
if __name__ == '__main__':
main()
The example is supposed to represent an MVC structure (like the one in Figure 4 -- without the Model) where the controller (TestViewController) receives a reference to the view (TestView) and connects the clicked signal from the view's button view.btn to its function self.buttonClicked.
I'm sure the line view.btn.clicked.connect(self.buttonClicked) is executed but, apparently, it has no effect. Does anyone knows how to solve that?
Update (awful solution):
In the example, if I replace the line
view.btn.clicked.connect(self.buttonClicked)
with
view.clicked = self.clicked
view.btn.clicked.connect(view.clicked)
it works. I'm still not happy with that.

The reason it is not working is because the controller class is being garbage collected before you can ever click anything for it.
When you set view.clicked = self.clicked, what you're actually doing is making one of the objects from the controller persist on the view object so it never gets cleaned up - which isn't really the solution.
If you store your controller to a variable, it will protect it from collection.
So if you change your code above to read:
ctrl = TestViewController(view)
You'll be all set.
That being said - what exactly you are trying to do here, I am not sure...it seems you're trying to setup an MVC system for Qt - but Qt already has a pretty good system for that using the Qt Designer to separate the interface components into UI (view/template) files from controller logic (QWidget subclasses). Again, I don't know what you are trying to do and this may be a dumb down version of it, but I'd recommend making it all one class like so:
from PyQt4 import QtGui
import sys
class TestView(QtGui.QWidget):
def __init__(self):
super(TestView, self).__init__()
self.initUI()
def initUI(self):
self.btn = QtGui.QPushButton('Button', self)
self.btn.resize(self.btn.sizeHint())
self.btn.move(50, 50)
self.btn.clicked.connect(self.buttonClicked)
def buttonClicked(self):
print 'clicked'
def main():
app = QtGui.QApplication(sys.argv)
view = TestView()
view.show()
app.exec_()
if __name__ == '__main__':
main()
Edit: Clarifying the MVC of Qt
So this above example doesn't actually load the ui dynamically and create a controller/view separation. Its a bit hard to show on here. Best to work through some Qt/Designer based examples/tutorials - I have one here http://bitesofcode.blogspot.com/2011/10/introduction-to-designer.html but many can be found online.
The short answer is, your loadUi method can be replace with a PyQt4.uic dynamic load (and there are a number of different ways to set that up) such that your code ultimately reads something like this:
from PyQt4 import QtGui
import PyQt4.uic
import sys
class TestController(QtGui.QWidget):
def __init__(self):
super(TestController, self).__init__()
# load view
uifile = '/path/to/some/widget.ui'
PyQt4.uic.loadUi(uifile, self)
# create connections (assuming there is a widget called 'btn' that is loaded)
self.btn.clicked.connect(self.buttonClicked)
def buttonClicked(self):
print 'clicked'
def main():
app = QtGui.QApplication(sys.argv)
view = TestController()
view.show()
app.exec_()
if __name__ == '__main__':
main()
Edit 2: Storing UI references
If it is easier to visualize this concept, you Can also store a reference to the generated UI object:
from PyQt4 import QtGui
import PyQt4.uic
import sys
class TestController(QtGui.QWidget):
def __init__(self):
super(TestController, self).__init__()
# load a view from an external template
uifile = '/path/to/some/widget.ui'
self.ui = PyQt4.uic.loadUi(uifile, self)
# create connections (assuming there is a widget called 'btn' that is loaded)
self.ui.btn.clicked.connect(self.buttonClicked)
def buttonClicked(self):
print 'clicked'
def main():
app = QtGui.QApplication(sys.argv)
view = TestController()
view.show()
app.exec_()
if __name__ == '__main__':
main()