How can QPixmaps get auto-resized in PyQt6 when the Mainwindow is resized?

Question

I'm playing around with QPixmaps in PyQt. I want to make them resize while maintaining the same aspect ratio when the window resizes, but when I try, I can only make the window bigger, never smaller.

Why is this, and is there a workaround?

Here is the code:

from PyQt6.QtCore import Qt
from PyQt6.QtGui import QPixmap
from PyQt6.QtWidgets import QApplication, QMainWindow, QLabel, QVBoxLayout, QWidget

class ResizablePixmapWidget(QWidget):
    def __init__(self, pixmap: QPixmap, parent=None):
        super().__init__(parent)
        self.original_pixmap = pixmap
        self.pixmap_label = QLabel(self)
        self.pixmap_label.setPixmap(self.original_pixmap)

        layout = QVBoxLayout(self)
        layout.addWidget(self.pixmap_label)
        layout.setContentsMargins(0, 0, 0, 0)

    def resizeEvent(self, event):
        widget_size = self.size()
        scaled_pixmap = self.original_pixmap.scaled(widget_size, Qt.AspectRatioMode.KeepAspectRatio, Qt.TransformationMode.SmoothTransformation)
        self.pixmap_label.setPixmap(scaled_pixmap)
        self.pixmap_label.resize(scaled_pixmap.size())
        # self.pixmap_label.adjustSize()

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

        # Replace 'path_to_image.jpg' with the path of your image file
        pixmap = QPixmap("path_to_image.jpg")
        resizable_pixmap_widget = ResizablePixmapWidget(pixmap, self)

        self.setCentralWidget(resizable_pixmap_widget)
        self.setWindowTitle('Resizable QPixmap')

if __name__ == '__main__':
    import sys

    app = QApplication(sys.argv)
    main_window = MainWindow()
    main_window.show()
    sys.exit(app.exec())

I've tried to apply the QPixmap to custom QWidget (as seen above) and also a regular Qlablel.

from PyQt6.QtCore import Qt
from PyQt6.QtGui import QPixmap
from PyQt6.QtWidgets import QApplication, QMainWindow, QLabel, QVBoxLayout, QWidget

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

        # Replace 'path_to_image.jpg' with the path of your image file
        pixmap = QPixmap("path_to_image.jpg")
        scaled_pixmap = pixmap.scaled(self.size(), Qt.AspectRatioMode.KeepAspectRatio, Qt.TransformationMode.SmoothTransformation)
        pixmap_label = QLabel(self)
        pixmap_label.setPixmap(scaled_pixmap)

        self.setCentralWidget(pixmap_label)
        self.setWindowTitle('Resizable QPixmap')

if __name__ == '__main__':
    import sys

    app = QApplication(sys.argv)
    main_window = MainWindow()
    main_window.show()
    sys.exit(app.exec())

I've tried the available aspect ratio modes (KeepAspectRatio, KeepAspectRatioByExpanding & KeepAspectRatio).

In my actual code I gave up and just used a QPushbutton to rezise the QPixmap manually when I resize the window. But this isn't very elegant.