WhyCan Forum(哇酷开发者社区)

UI files
Both packages use slightly different approaches for loading .ui files exported from Qt Creator/Designer. PyQt5 provides the uic submodule which can be used to load UI files directly, to produce an object. This feels pretty Pythonic (if you ignore the camelCase).

import sys
from PyQt5 import QtWidgets, uic

app = QtWidgets.QApplication(sys.argv)

window = uic.loadUi("mainwindow.ui")
window.show()
app.exec()
The equivalent with PySide2 is one line longer, since you need to create a QUILoader object first. Unfortunately the api of these two interfaces is different too (.load vs .loadUI) and take different parameters.

import sys
from PySide2 import QtCore, QtGui, QtWidgets
from PySide2.QtUiTools import QUiLoader

loader = QUiLoader()

app = QtWidgets.QApplication(sys.argv)
window = loader.load("mainwindow.ui", None)
window.show()
app.exec_()
To load a UI onto an object in PyQt5, for example in your QMainWindow.__init__, you can call uic.loadUI passing in self (the target widget) as the second parameter.

import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5 import uic


class MainWindow(QtWidgets.QMainWindow):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        uic.loadUi("mainwindow.ui", self)


app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()
The PySide2 loader does not support this — the second parameter to .load is the parent widget of the widget you're creating. This prevents you adding custom code to the __init__ block of the widget, but you can work around this with a separate function.

import sys
from PySide2 import QtWidgets
from PySide2.QtUiTools import QUiLoader

loader = QUiLoader()

def mainwindow_setup(w):
    w.setTitle("MainWindow Title")

app = QtWidgets.QApplication(sys.argv)

window = loader.load("mainwindow.ui", None)
mainwindow_setup(window)
window.show()
app.exec()
Converting UI files to Python
Both libraries provide identical scripts to generate Python importable modules from Qt Designer .ui files. For PyQt5 the script is named pyuic5 —

pyuic5 mainwindow.ui -o MainWindow.py
You can then import the UI_MainWindow object, subclass using multiple inheritance from the base class you're using (e.g. QMainWIndow) and then call self.setupUI(self) to set the UI up.

import sys
from PyQt5 import QtWidgets
from MainWindow import Ui_MainWindow

class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.setupUi(self)


app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec()
For PySide2 it is named pyside2-uic —

pyside2-uic mainwindow.ui -o MainWindow.py
The subsequent setup is identical.

import sys
from PySide2 import QtWidgets
from MainWindow import Ui_MainWindow

class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.setupUi(self)


app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()
For more information on using Qt Designer with either PyQt5 or PySide2 see the Qt Creator tutorial.

import sys, os

#os.environ["QT_BINDING"] = "PyQt5"
os.environ["QT_BINDING"] = "PySide2"

if os.environ["QT_BINDING"] == "PyQt5": ###'PyQt5.Widgets' in sys.modules:
    print("import PyQt5")
    from PyQt5.QtWidgets import QApplication, QLabel, QPushButton, QMainWindow, QVBoxLayout, QDialog
    from PyQt5.QtCore import pyqtSignal as Signal, pyqtSlot as Slot
    from PyQt5 import uic
elif os.environ["QT_BINDING"] == "PySide2":
    print("import PySide2")
    from PySide2.QtWidgets import QApplication, QLabel, QPushButton, QMainWindow, QVBoxLayout, QDialog
    from PySide2.QtCore import Signal, Slot
    from PySide2.QtUiTools import QUiLoader


if __name__ == '__main__':
    app = QApplication(sys.argv)

    if os.environ["QT_BINDING"] == "PyQt5":
        window = uic.loadUi("mainwindow.ui")
    elif os.environ["QT_BINDING"] == "PySide2":
        uiloader = QUiLoader()
        window = uiloader.load("mainwindow.ui")

    window.show()

    sys.exit(app.exec_())

import sys, os

os.environ["QT_BINDING"] = "PyQt5"
# os.environ["QT_BINDING"] = "PySide2"

if os.environ["QT_BINDING"] == "PyQt5": ###'PyQt5.Widgets' in sys.modules:
    print("import PyQt5")
    from PyQt5.QtWidgets import QApplication, QLabel, QPushButton, QMainWindow, QVBoxLayout, QDialog
    from PyQt5.QtCore import pyqtSignal as Signal, pyqtSlot as Slot, QTimer
    from PyQt5 import uic
elif os.environ["QT_BINDING"] == "PySide2":
    print("import PySide2")
    from PySide2.QtWidgets import QApplication, QLabel, QPushButton, QMainWindow, QVBoxLayout, QDialog
    from PySide2.QtCore import Signal, Slot, QTimer
    from PySide2.QtUiTools import QUiLoader


@Slot(int)
def SlotTimeOut(i):
    print("定时器" + str(i) + "超时 timout: ")


if __name__ == '__main__':
    app = QApplication(sys.argv)

    if os.environ["QT_BINDING"] == "PyQt5":
        window = uic.loadUi("mainwindow.ui")
    elif os.environ["QT_BINDING"] == "PySide2":
        uiloader = QUiLoader()
        window = uiloader.load("mainwindow.ui")

    a = 0
    timer1 = QTimer()
    timer1.timeout.connect(lambda: SlotTimeOut(1))
    timer1.start(1000)

    timer2 = QTimer()
    timer2.timeout.connect(lambda: SlotTimeOut(2))
    timer2.start(3005)

    window.show()

    sys.exit(app.exec_())

import PyQt5
定时器1超时 timout: 
定时器1超时 timout: 
定时器1超时 timout: 
定时器2超时 timout: 
定时器1超时 timout: 
定时器1超时 timout: 
定时器1超时 timout: 
定时器2超时 timout: 
定时器1超时 timout: 

import sys,os
from PySide2.QtWidgets import QApplication, QPushButton, QTextEdit, QMainWindow, QVBoxLayout, QWidget

def SoltTest(i):
    print("slot test" + str(i))

if __name__ == '__main__':
    app = QApplication(sys.argv)

    window = QMainWindow()

    boxlayout = QVBoxLayout(window)
    button1 = QPushButton("统计1", window)
    button2 = QPushButton("统计2", window)
    textedit1 = QTextEdit(window)

    button1.clicked.connect(lambda: SoltTest(1))
    button2.clicked.connect(lambda: SoltTest(2))

    boxlayout.addWidget(textedit1)
    boxlayout.addWidget(button1)
    boxlayout.addWidget(button2)

    mainwidget = QWidget()
    mainwidget.setLayout(boxlayout)

    window.setCentralWidget(mainwidget)
    window.show()

    sys.exit(app.exec_())