窗口背景主要包括：背景色和背景图片。设置窗口背景主要有三种方法：

• 使用QSS设置窗口背景。
• 使用QPalette设置窗口背景。
• 实现paintEvent，使用QPainter绘制背景。

使用setStyleSheet设置窗口背景图片

import sys
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *


if __name__ == "__main__":
    app = QApplication(sys.argv)
    win = QMainWindow()
    win.setWindowTitle("界面背景图片设置")
    win.resize(350, 250)
    win.setObjectName("MainWindow")
    win.setStyleSheet("#MainWindow{border-image:url(./pyqt5/python.jpg)}")
    win.show()
    sys.exit(app.exec_())

使用setStyleSheet设置窗口背景颜色

import sys
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *


if __name__ == "__main__":
    app = QApplication(sys.argv)
    win = QMainWindow()
    win.setWindowTitle("界面背景图片设置")
    win.resize(350, 250)
    win.setObjectName("MainWindow")
    win.setStyleSheet("#MainWindow{background-color:yellow}")
    win.show()
    sys.exit(app.exec_())

使用QPalette设置窗口背景颜色

import sys
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *

if __name__ == "__main__":
    app = QApplication(sys.argv)
    win = QMainWindow()
    win.setWindowTitle("QPalette调色板设置背景颜色")
    win.resize(350, 150)
    palette = QPalette()
    palette.setColor(QPalette.Background, Qt.red)
    win.setPalette(palette)
    win.show()
    sys.exit(app.exec_())

使用QPalette设置窗口背景图片

import sys
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *




if __name__ == "__main__":
    app = QApplication(sys.argv)
    win = QMainWindow()
    win.setWindowTitle("QPalette设置背景图片")
    palette = QPalette()
    palette.setBrush(QPalette.Background, QBrush(QPixmap("./pyqt5/python.jpg")))
    win.setPalette(palette)
    win.resize(800, 600)
    win.show()
    sys.exit(app.exec_())

使用paintEvent设置窗口背景颜色

import sys
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *

class WinForm(QWidget):
    def __init__(self, parent=None):
        super(WinForm, self).__init__(parent)
        self.setWindowTitle("paintEvent设置背景色")

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.setBrush(Qt.blue)
        painter.drawRect(self.rect())

if __name__ == "__main__":
    app = QApplication(sys.argv)
    win = WinForm()
    win.show()
    sys.exit(app.exec_())

使用paintEvent设置窗口背景图片

import sys
from PyQt5.QtGui import *
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *

class WinForm(QWidget):
    def __init__(self, parent=None):
        super(WinForm, self).__init__(parent)
        self.setWindowTitle("paintEvent设置背景图片")

    def paintEvent(self, event):
        painter = QPainter(self)
        pixmap = QPixmap("./pyqt5/images/screen1.jpg")
        painter.drawPixmap(self.rect(), pixmap)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    win = WinForm()
    win.show()
    sys.exit(app.exec_())