Can't get custom PyQt5 widget plugin to show up in Qt designer running in Virtualenv (Ubuntu)

Question

I am trying to use custom widget on PyQt Designer, using code from: https://github.com/baoboa/pyqt5/blob/master/examples/designer/plugins/plugins.py and both plugin and widget from https://github.com/tranter/blogs/tree/master/PythonPlugin.

My Designer is installed win ubuntu via apt-get designer and as per

QLibraryInfo.location(QLibraryInfo.BinariesPath) is in /usr/lib/qt5/bin

the led widget and plugin are in two directories at same level of the run script (see the code):

#!/usr/bin/env python3


#############################################################################
##
## Copyright (C) 2013 Riverbank Computing Limited.
## All rights reserved.
##
## This file is part of the examples of PyQt.
##
## You may use this file under the terms of the BSD license as follows:
##
## "Redistribution and use in source and binary forms, with or without
## modification, are permitted provided that the following conditions are
## met:
##   * Redistributions of source code must retain the above copyright
##     notice, this list of conditions and the following disclaimer.
##   * Redistributions in binary form must reproduce the above copyright
##     notice, this list of conditions and the following disclaimer in
##     the documentation and/or other materials provided with the
##     distribution.
##   * Neither the name of Riverbank Computing Limited nor the names of
##     its contributors may be used to endorse or promote products
##     derived from this software without specific prior written
##     permission.
##
## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
##
#############################################################################


import sys
import os

from PyQt5.QtCore import QLibraryInfo, QProcess, QProcessEnvironment
from PyQt5.QtWidgets import QApplication, QMessageBox

designer_bin = QLibraryInfo.location(QLibraryInfo.BinariesPath)

print('designer_bin = QLibraryInfo.location(QLibraryInfo.BinariesPath) :', designer_bin)

app = QApplication(sys.argv)

QMessageBox.information(None, "PyQt Designer Plugins",
        "<p>This example will start Qt Designer when you click the <b>OK</b> "
        "button.</p>"
        "<p>Before doing so it sets the <tt>PYQTDESIGNERPATH</tt> environment "
        "variable to the <tt>python</tt> directory that is part of this "
        "example.  This directory contains all the example Python plugin "
        "modules.</p>"
        "<p>It also sets the <tt>PYTHONPATH</tt> environment variable to the "
        "<tt>widgets</tt> directory that is also part of this example.  This "
        "directory contains the Python modules that implement the example "
        "custom widgets.</p>"
        "<p>All of the example custom widgets should then appear in "
        "Designer's widget box in the <b>PyQt Examples</b> group.</p>")

# Tell Qt Designer where it can find the directory containing the plugins and
# Python where it can find the widgets.
base = os.path.dirname(__file__)

print('base :',base)

env = QProcessEnvironment.systemEnvironment()





env.insert('PYQTDESIGNERPATH', os.path.join(base, 'python3'))
env.insert('PYTHONPATH', os.path.join(base, 'widgets3'))

# Start Designer.
designer = QProcess()
designer.setProcessEnvironment(env)




designer_bin = '/usr/lib/qt5/bin/designer'

print('\ndesigner_bin :', designer_bin)


 


def process_finished():

    #designer.waitForFinished(-1)
    print('finished')
    
    sys.exit()




designer.start(designer_bin)        


#designer.setProgram(designer_bin)  #anche con questo non cambia da virtualenv non funza
#designer.startDetached()           # da usare insieme a sopra

designer.finished.connect(process_finished)



print('designer.pid() :', designer.pid())

print(env.keys())

print('\nenv PYTHONPATH :', env.value('PYTHONPATH'))

print('\nenv PYQTDESIGNERPATH :', env.value('PYQTDESIGNERPATH'))

sys.exit(app.exec_())

When I launch the script in main enviroment I can see my custom widget:

but when I run the script from inside a virtualenv the led custom widget doesnt show up.

I can install designer in my virtualenv via pip install pyqt5-tools and the run

pyqt5-tools designer -p **PATH_to_both_widget.py_widgetplugin.py** to have my custom

widgets available, but I can't figure out why the first approach doesnt work and is draving me crazy, any idea about it

Answer 1

The key is to modify the includeFile method since the import is built from there, for my project structure:

??? scripts
?   ??? designer.py
?   ??? plugins
?       ??? ledplugin.py
??? src
    ??? lib
    ?   ??? __init__.py
    ?   ??? ledwidget.py
    ??? main.py
    ??? ui
        ??? main.ui

def includeFile(self):
    # IMPORT:
    # from lib.ledwidget import LedWidget
    return "lib.ledwidget"

designer.py

import sys
import os.path

from PyQt5.QtCore import QCoreApplication, QLibraryInfo, QProcess, QProcessEnvironment


def main():
    app = QCoreApplication([])
    base_dir = os.path.dirname(__file__)
    plugins_dir = os.path.join(base_dir, "plugins")
    lib_dir = os.path.join(base_dir, "..", "src", "lib")

    env = QProcessEnvironment.systemEnvironment()
    env.insert("PYQTDESIGNERPATH", plugins_dir)
    env.insert("PYTHONPATH", lib_dir)

    # Start Designer.
    designer = QProcess()
    designer.setProcessEnvironment(env)

    designer_bin = QLibraryInfo.location(QLibraryInfo.BinariesPath)

    if sys.platform == "darwin":
        designer_bin += "/Designer.app/Contents/MacOS/Designer"
    else:
        designer_bin += "/designer"

    designer.start(designer_bin)
    designer.waitForFinished(-1)

    sys.exit(designer.exitCode())


if __name__ == "__main__":
    main()

The complete example is found here.