How to install PyQt5 on a new virtualenv and work on an IDLE

Question

I installed PyQt5 globally on my win7 system (python 3.3), using the installer provided from the official riverbank website.

Then i created a new –no-site-package

Answer 1

How I got my PyQt5, Python33 Windows7x64 within a virtualenv working:

Firstly, ensure you have matched 64 or 32 bit versions of everything. I am developing on a 64bit platform and am using 64bit versions. I did not fully test this with 32 bit. Please read thoroughly.

• Installed Python33 x64 using Windows installer binaries.
• Installed PyQt5 x64 from riverbank using the MSI installer into the default Python33. PIP won't work.
• Create a virtualenv using the Python33 as your base, no site packages.
• Copy the PyQt5 folder from Python33/Lib/site-packages/ into your virtualenv/Lib/site-packages.
• DO NOT DELETE THE PyQT5 folder!

Ensure PyQt5 is working on the base Python33 install:

from PyQt5 import QtCore, QtGui, QtWidgets

Create a main window and launch it. If testing with PyQt4 code, a few classes have been swapped around. (Within QtGui and QtWidgets for example)

from PyQt5 import QtGui, QtWidgets, QtCore

class Main(QtWidgets.QMainWindow):

def __init__(self):
    print("Main __init__ fired")
    QtWidgets.QMainWindow.__init__(self)

    #Setup the UI
    print("Setting up UI")
    self.ui = Ui_MainWindow()
    self.ui.setupUi(self)

def main():
    print("fired main()")

    #Setup the main application object
    app = QtWidgets.QApplication(sys.argv)

    window = Main()
    window.show()

    sys.exit(app.exec_())

#Run GUI
if __name__ == "__main__":
    main()

If you get this error "..failed to start, could not find or load the Qt platform plugin "windows." (or similar), YOU MUST UPDATE your DirectX. Do this through Microsoft.

Once you are entirely sure PyQt5 is working within Windows, then continue.

• Activate your virtualenv where you copied the PyQt5 folder to

• Ensure PyQt5 can be imported from within your virtualenv. You may need to manipulate paths depending on what IDE you are using. Run an import in your virtualenv

  from PyQt5 import QtCore, QtGui, QtWidgets

• Try to run the same application again from inside this virtualenv

OH NO! Another error with dlls! What gives? The paths to the QT dll libraries are wrong inside the virtualenv. It happens even if you tell PyQt5 to install directly to your virtualenv. You MUST add the paths to libraryPaths before creating the QApplication object. Here is a solution (Replace venv with your virtualenv path):

def main():
    print("fired main()")

    #ADD THE FOLLOWING BEFORE CREATING A QApplication()
    QtCore.QCoreApplication.setLibraryPaths(['C:/venv/Lib/site-packages/PyQt5/plugins'])

    #Ensure path was added and correct
    print(QtCore.QCoreApplication.libraryPaths())

    #Setup the main application object
    app = QtWidgets.QApplication(sys.argv)

    #See what the paths were
    print(app.libraryPaths())

    window = Main()
    window.show()

    sys.exit(app.exec_())

Now the code should run from all inside your virtualenv. You can delete the PyQt5 directory from your base install, or move it to another place if you need it in the future.

There is most likely a way to boilerplate the path in a relative way, but this could create an issue with cx-freeze. Speaking of which.

Now you're all done and you go to cx-freeze your PyQt5 app into a nice exe. You go to run it and OH NO! more dll troubles.

You can manually copy libEGL.dll from site-packages/PyQt5 to the root build folder of your application, or add the following lines to your setup.py file for cx-freeze:

import sys

from cx_Freeze import setup, Executable

#ADD THIS MUST INCLUDE FOR Windows 7.
include_files = [('c:/venv/Lib/site-packages/PyQt5/libEGL.dll', 'libEGL.dll')]

setup(
    name="My App",
    version="0.1",
    description="PyQt5 App.",

    #ADD THIS
    options={'build_exe': {'include_files': include_files}},

    executables=[Executable("c:/venv/src/myApp_main.py",
                            base="Win32GUI",
                            targetName="MyApp.exe")])

Answer 2

I faced the same issue installing PyQt5 and SIP. The solution for resolving this problem for PyQt4 as specified on Is it possible to add PyQt4/PySide packages on a Virtualenv sandbox? worked for me.

I manually created symlinks to the PyQt5 and sip.so from within the virtualenv/site-packages directory. An ugly solution but gets things working.

Answer 3

Both "pip install sip" and "pip install PyQt5" inside the virtual enviroment are returning errors.

If the errors you're referring to are:

Could not find any downloads that satisfy the requirement [pyqt5|sip]

and

No distributions at all found for [pyqt5|sip]

Then this answer should shed light on this. Basically, PyPI is only providing a link to the homepage and/or source -- not a downloadable package or egg. Here are the links to PyQt5 and SIP PyPI pages. I know it seems strange that a package manager wouldn't provide packages, but that's the way it is.

You'll have to download, compile, and install sip and pyqt5 from source, inside your virtualenv. I wish I could provide details but I'm currently working through this myself.

Answer 4

Assuming you have PyQt5 installed globally, there's a way you can give your virtualenv access to it without using --system-site-packages. A package called vext makes it possible. It works with other packages as well, but in this case we'll just be setting up the PyQt5 support.

Run the following command from within your virtualenv and you should be good to go:

pip install vext.pyqt5

---

To check the status, run vext -l. You should see something like the following:

Running in virtualenv [enabled]
pyqt5.vext

Or, run vext -c pyqt5.vext. You should see something like the following:

import sip: [success]
import PyQt5: [success]

Alternatively you can just try to import PyQt5, e.g. python -c 'import PyQt5'.

Answer 5

Anon's solution of adding a Qt libraryPath worked for me. I am using Anaconda3 on Windows. But I found an alternative.

Copy the file …\Anaconda3\qt.conf to the Scripts folder in the virtual environment. Now I don't need to change any Python code.

The conf file seems to have been created by …\Anaconda3\Scripts\.qt-post-link.bat.