is there anybody to explain of sizepolicy?

choiinkuk

i worte some test code to understand different of sizepolicy.

QHBoxLayout *layout = new QHBoxLayout();
layout->setContentsMargins(0,0,0,0);

QPushButton *button1 = new QPushButton("minimun", this);
button1->setSizePolicy(QSizePolicy::Minimum, QSizePolicy::Fixed);

QPushButton *button2 = new QPushButton("preferred", this);
button2->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);

QPushButton *button3 = new QPushButton("maximum", this);
button3->setSizePolicy(QSizePolicy::Maximum, QSizePolicy::Fixed);

layout->addWidget(button1);
layout->addWidget(button2);
layout->addWidget(button3);

this->setLayout(layout);

Alt text

i know difference of maximum and minimum,
but i don't understand difference of minimum and preferred,
because the stretching behavior of minimum is as same as it of preferred.

i did read manpage serveral time, but i can't understand.

is there anybody to explain of sizepolicy?

thank you.

JKSH

Hi, and welcome to the Qt Dev Net!

Minimum: The widget is not allowed to be smaller than its sizeHint().
Preferred: The widget is allowed to be smaller than its sizeHint().

This is described at http://doc.qt.io/qt-5/qsizepolicy.html#Policy-enum