qt-sizetest.cpp

/* compile as C++11 */

#include <QApplication>

#include <QPushButton>
#include <QSlider>
#include <QLabel>
#include <QLayout>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QWidget w;

    w.setWindowTitle("QWidget Size Test");

    QVBoxLayout *layout = new QVBoxLayout;
    w.setLayout(layout);

    int defaultSize = 20;

    QPushButton *button = new QPushButton;
    layout->addWidget(button);
    layout->addStretch();
    button->setMinimumSize(defaultSize, defaultSize);
    button->setMaximumSize(defaultSize, defaultSize);

    QGridLayout *grid = new QGridLayout;
    layout->addLayout(grid);

    grid->addWidget(new QLabel("Minimum Height"), 0, 0);
    grid->addWidget(new QLabel("Minimum Width"), 1, 0);

    QSlider *heightSlider = new QSlider(Qt::Horizontal);
    grid->addWidget(heightSlider, 0, 1);
    heightSlider->setRange(defaultSize, 500);
    QObject::connect(heightSlider, &QSlider::valueChanged, [=](int height) {
        button->setMinimumHeight(height);
    });

    QSlider *widthSlider = new QSlider(Qt::Horizontal);
    grid->addWidget(widthSlider, 1, 1);
    widthSlider->setRange(defaultSize, 500);
    QObject::connect(widthSlider, &QSlider::valueChanged, [=](int width) {
        button->setMinimumWidth(width);
    });

    w.show();

    return a.exec();
}