Adding border with stylesheet changes QLineEdit default size

[JesusM97]

@SGaist I will try that, thanks!

[JesusM97]

@SGaist I tried with QFormLayout and I have same problem.
I found that with QFormLayout the problem appears when I add this line of code:

formLayout.setFieldGrowthPolicy(QFormLayout.FieldsStayAtSizeHint)

but I don't want the fields to grow so I need that line.

[SGaist]

Can you provide a complete minimal script that shows that behaviour ?

[JesusM97]

@SGaist Of course. I created a QMainWindow with a QLineEdit and a QPushButton. When I press the button, there is a function that checks if the QLineEdit is empty. If it is empty it changes its border to red but it also changes the field size:

import sys

from PySide2 import QtWidgets
from PySide2.QtCore import Qt
from PySide2.QtWidgets import QMainWindow, QFormLayout, QLineEdit, QWidget, QVBoxLayout, QPushButton

def checkEmpty(lineEdit):
    if lineEdit.text() == "":
        lineEdit.setStyleSheet("border-style: solid;border-width: 2px;border-color: red")


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)

    main_window = QMainWindow()
    centalWidget = QWidget()
    main_window.setCentralWidget(centalWidget)

    verticalLayout = QVBoxLayout()
    formLayout = QFormLayout()
    inputEdit = QLineEdit()
    formLayout.addRow("Input", inputEdit)
    formLayout.setRowWrapPolicy(QFormLayout.DontWrapRows)
    formLayout.setFieldGrowthPolicy(QFormLayout.FieldsStayAtSizeHint)
    formLayout.setFormAlignment(Qt.AlignHCenter | Qt.AlignTop)
    verticalLayout.addLayout(formLayout)

    okButton = QPushButton("OK")
    okButton.clicked.connect(lambda: checkEmpty(inputEdit))
    verticalLayout.addWidget(okButton)

    centalWidget.setLayout(verticalLayout)

    main_window.show()

    app.exec_()

When I run the app this is what it shows:

and when I click the button this is what happens:

This doesn't happen if I remove:

formLayout.setFieldGrowthPolicy(QFormLayout.FieldsStayAtSizeHint)

but I need it

[SGaist]

Can you test that with PySide6 ?
I tried it on macOS and the QLineEdit just changed the border without the changing it size with the sample script you posted.

[JesusM97]

@SGaist Really? I tried the example with PySide6 and I have the same result. Did you add

formLayout.setFieldGrowthPolicy(QFormLayout.FieldsStayAtSizeHint)

to your form layout? If not it doesn't happen.

[SGaist]

Which version of PySide6 do you have ?

[JesusM97]

@SGaist PySide6 6.3.1

[SGaist]

Yes, I used your example verbatim.

It looks like it might be something Windows specific.

I also monkeypatched sizeHint to return a custom value and its properly called twice (once at startup and once when clicking the OK button) and size stays the same. 6.3.0 and 6.3.1 are consistent.

[JesusM97]

@SGaist Well, so I will try to get the sizeHint at startup and then try to set the value after modifying the border. Maybe this will work.

EDIT: I have tried that and it works.

When I create the QLineEdit, I set its fixed size based on its size hint.

 verticalLayout = QVBoxLayout()
 formLayout = QFormLayout()
 inputEdit = QLineEdit()
 size = inputEdit.sizeHint()
 inputEdit.setFixedSize(size)
 formLayout.addRow("Input", inputEdit)

Now, when I change the QLineEdit Stylesheet the field size doesn't change.