python PyQt4 scripts won't run

iFunction · 04-04-2016, 10:26 AM

Hi there,

First off, apologies if this is in the wrong place, but I'm at a loss right now.

I'm trying to learn how to do gui in python, and I am having trouble just getting a window on the screen using this script I found this on this internet. I am fairly sure it is right as it corresponds very well to another thing I was trying, but on execution, nothing happens, the prompt doesn't return any error, just nothing happens, I have left in all credits, as I have copied it directly and just want to get it working:

Code:

#!/usr/bin/python
# -*- coding: utf-8 -*-

"""
ZetCode PyQt4 tutorial 

In this example, we create a simple
window in PyQt4.

author: Jan Bodnar
website: zetcode.com 
last edited: October 2011
"""

import sys
from PyQt4 import QtGui


def main():
    
    app = QtGui.QApplication(sys.argv)

    w = QtGui.QWidget()
    w.resize(250, 150)
    w.move(300, 300)
    w.setWindowTitle('Simple')
    w.show()
    
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

Please can someone enlighten me as to why I am not getting a window on the screen using this code, Yet when I can with this:

Code:

import sys
from PyQt4 import QtGui
app = QtGui.QApplication(sys.argv)
window = QtGui.QWidget()
window.show()

In fact, I just tried putting this in a script and it doesn't work as a script either, so I am doing something very wrong, as it works when you just plug it straight into the shell. However I can print text from a script, that works. I'm at a bit of a loss now, as I must have the right libraries installed to run this, and I can run other python scripts. I am using a Raspberry Pi3 by the way.

Any help on this would be very much appreciated.

IFunction

iFunction · 04-04-2016, 11:40 AM

I have made something of a breakthrough, in that a very simple version of this works without any of the main function by adding:

Code:

app.exec_()

which apparently is required for linux, but I can't get it to work in the script here. any ideas?

norobro · 04-04-2016, 12:57 PM

No idea what's wrong but FYI your original code works fine on my machine:

Code:

>>> import sys
>>> from PyQt4.QtCore import QT_VERSION_STR
>>> from PyQt4.Qt import PYQT_VERSION_STR
>>> print sys.version
2.7.11+ (default, Mar 23 2016, 11:35:56) 
[GCC 5.3.1 20160316]
>>> print QT_VERSION_STR
4.8.7
>>> print PYQT_VERSION_STR
4.11.4

iFunction · 04-06-2016, 05:24 AM

Ok, I copied what you did here, and get the following:

Code:

>>> print sys.version
2.7.9 (default, Mar 8 2015, 00:52:26)
[GCC 4.9.2]
>>> print QT_VERSION_STR
4.8.6
>>> print PYQT_VERSION_STR
4.11.2

This is after a full update on a fresh Raspbian_Jessie install update and upgrade, so I am assuming this is as updated as is supported for the Raspberry Pi.