如何在 PyQt5 中制作屏幕旋转功能？

QTransform & QTransform ::旋转（qreal 角度，Qt::Axis 轴 = Qt::ZAxis）

将坐标系绕指定轴逆时针旋转指定角度，并返回对矩阵的引用。

请注意，如果您将 QTransform 应用于在小部件坐标中定义的点，则旋转方向将是顺时针方向，因为 y 轴指向下方。
角度以度数指定。

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


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        
        self.centralWidget = QWidget()                              
        self.setCentralWidget(self.centralWidget)                  
        
        self.lbl = QtWidgets.QLabel()
        self.lbl.setMinimumSize(500, 500)                              # +++
        self.lbl.setAlignment(QtCore.Qt.AlignCenter)                   # +++
        
        self.pix = QtGui.QPixmap("lena-2.png")  #.scaled(400, 400)     # ваше фото
        self.lbl.setPixmap(self.pix)
        
        self.btn = QPushButton()
        self.btn.setText("Кнопка")
        self.btn.setStyleSheet("""
            background: pink; 
            color: black; 
            border-radius: 34px;
        """)
        self.btn.setFont(QtGui.QFont("Pusia-Bold.otf", 17, QtGui.QFont.Bold))
        self.btn.setFixedSize(300, 150)
        self.btn.setCheckable(True)
        self.btn.clicked.connect(self.show_image)

        layout = QGridLayout(self.centralWidget)
        layout.addWidget(self.lbl, 0, 0, Qt.AlignCenter)
        layout.addWidget(self.btn, 1, 0, Qt.AlignHCenter | Qt.AlignBottom)
        
        self.eff = QGraphicsOpacityEffect()
        self.eff.setOpacity(0.0)        
        self.lbl.setGraphicsEffect(self.eff)
        
        self.animation = QPropertyAnimation(self.eff, b'opacity')
        self.animation.setDuration(1000)   

# +++ vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
        QtCore.QTimer.singleShot(10, self.btn.click)                    # +++  

        self.rotation = 0                            
        self.num = 0
        self.timer = QtCore.QTimer()
        self.timer.setInterval(100)
        self.timer.timeout.connect(self.rotate_pixmap)
        self.timer.start()

    def rotate_pixmap(self):
        self.num += 1
        if self.num == 25:
            self.timer.stop()
            self.num = 0
            return
    
        pixmap = self.pix.copy()
        self.rotation += 15
        transform = QtGui.QTransform().rotate(self.rotation)
        pixmap = pixmap.transformed(transform, QtCore.Qt.SmoothTransformation)
        self.lbl.setPixmap(pixmap)
# +++ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        
    def show_image(self):
        if not self.btn.isChecked():       
            self.animation.setStartValue(1)
            self.animation.setEndValue(0)
        else:    
            self.animation.setStartValue(0)
            self.animation.setEndValue(1)
            
            QtCore.QTimer.singleShot(5000, self.btn.click)   

        self.animation.start() 


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    ex = MainWindow()
    ex.resize(520, 600)                                               # +++
    ex.show()
    sys.exit(app.exec_())