Preferred QSizePolicy in PySide2

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preferred policy is very flexible policy. the size of widget can be smaller and larger than sizeHint().

let's check the example code right now.


from PySide2 import QtWidgets, QtCore

app = QtWidgets.QApplication([])

window = QtWidgets.QWidget()
layout = QtWidgets.QHBoxLayout()

PreferredButton = QtWidgets.QPushButton("Preferred Widget")
PreferredButton.setSizePolicy(QtWidgets.QSizePolicy.Preferred , QtWidgets.QSizePolicy.Preferred)

layout.addWidget(PreferredButton)
window.setLayout(layout)
window.show()

app.exec_()

I created one button and set the property of size policy to preferred for both of horizontal and vertical policies.

then, I run the application.




first one is default size that evaluated from minimumSizeHint() function. every built-in widgets has its own reimplemented size hint function.
I expected the size of widget is smaller when I decreased the size of window. but the size of widget is not smaller than first image. because minimum size is there.

reversely, when I increased the size of window, the size of widget is also increased.




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