PyQt5 Automatic widget resize

Question

I would like to resize automatically the widget size based on the window size.

example: if the window size increases also the widget inside the window have to increases.

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(800, 600)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.listWidget = QtWidgets.QListWidget(self.centralwidget)
        self.listWidget.setGeometry(QtCore.QRect(20, 20, 771, 551))
        self.listWidget.setObjectName("listWidget")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 21))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

Answer 1

all you have to do is use their Qlayouts or QHBoxlayouts or QVBoxlayouts. it will automatically resize unless you resize it.

EXAMPLE:

import sys

from PyQt5.QtWidgets import QApplication
from PyQt5.QtWidgets import QLabel
from PyQt5.QtWidgets import QPushButton
from PyQt5.QtWidgets import QVBoxLayout
from PyQt5.QtWidgets import QWidget

def greeting():
    #Slot function.
    if msg.text():
        msg.setText("")
    else:
        msg.setText("Hello World!")

app = QApplication(sys.argv)
window = QWidget()
window.setWindowTitle('Signals and slots')
layout = QVBoxLayout()

btn = QPushButton('Greet')
btn.clicked.connect(greeting)  # Connect clicked to greeting()

layout.addWidget(btn)
msg = QLabel('')
layout.addWidget(msg)
window.setLayout(layout)
window.show()
sys.exit(app.exec_())