how to add a background image to a main window without affecting the widgets in Pyqt5

Question

I would like to add a background image to my main window without changing the background image of pushbutton in it and also need to keep the aspect ratio

i tried with

self.centralWidget.setStyleSheet("background-image: url(The_Project_logo.png); background-repeat: no-repeat; background-position: center")

but this changes the background images of all widgets

Answer 1

Try it:

from PyQt5.QtWidgets import *

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.centralwidget = QWidget()
        self.setCentralWidget(self.centralwidget)

        self.pushButton1 = QPushButton("Button 1", self.centralwidget)
        self.pushButton2 = QPushButton("Button 2", self.centralwidget)

        lay = QHBoxLayout(self.centralwidget)
        lay.addWidget(self.pushButton1)
        lay.addWidget(self.pushButton2)


stylesheet = """
    MainWindow {
        background-image: url("D:/_Qt/img/cat.jpg"); 
        background-repeat: no-repeat; 
        background-position: center;
    }
"""

if __name__ == "__main__":
    import sys
    app = QApplication(sys.argv)
    app.setStyleSheet(stylesheet)     # <---
    window = MainWindow()
    window.resize(640, 640)
    window.show()
    sys.exit(app.exec_())

---

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):

        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(400, 300)
        self.centralWidget = QtWidgets.QWidget(MainWindow)
        self.centralWidget.setObjectName("centralWidget")

        self.horizontalLayout_2 = QtWidgets.QHBoxLayout(self.centralWidget)

        self.horizontalLayout_2.setContentsMargins(11, 11, 11, 11)
        self.horizontalLayout_2.setSpacing(6)
        self.horizontalLayout_2.setObjectName("horizontalLayout_2")
        self.horizontalLayout = QtWidgets.QHBoxLayout()
        self.horizontalLayout.setSpacing(6)
        self.horizontalLayout.setObjectName("horizontalLayout")
        self.start_button = QtWidgets.QPushButton(self.centralWidget)
        self.start_button.setObjectName("start_button")

        self.horizontalLayout.addWidget(self.start_button)
        self.stop_button = QtWidgets.QPushButton(self.centralWidget)
        self.stop_button.setObjectName("stop_button")
        self.horizontalLayout.addWidget(self.stop_button)
        self.horizontalLayout_2.addLayout(self.horizontalLayout)
        MainWindow.setCentralWidget(self.centralWidget)
        self.menuBar = QtWidgets.QMenuBar(MainWindow)
        self.menuBar.setGeometry(QtCore.QRect(0, 0, 400, 26))
        self.menuBar.setObjectName("menuBar")
        MainWindow.setMenuBar(self.menuBar)
        self.mainToolBar = QtWidgets.QToolBar(MainWindow)
        self.mainToolBar.setObjectName("mainToolBar")
        MainWindow.addToolBar(QtCore.Qt.TopToolBarArea, self.mainToolBar)
        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"))
        self.start_button.setText(_translate("MainWindow", "Start"))
        self.stop_button.setText(_translate("MainWindow", "Stop"))


class MyWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self):
        super().__init__()

        self.setupUi(self)


stylesheet = """
    QMainWindow {
        background-image: url("D:/_Qt/img/cat.jpg"); 
        background-repeat: no-repeat; 
        background-position: center;
    }
"""

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    app.setStyleSheet(stylesheet)

    w = MyWindow()
#   MainWindow = QtWidgets.QMainWindow()
#   ui = Ui_MainWindow()
#   ui.setupUi(MainWindow)
#   MainWindow.show()
    w.show()

    sys.exit(app.exec_())