void QToolBar::setIconSize(const QSize &iconSize) { Q_D(QToolBar); QSize sz = iconSize; if (!sz.isValid()) { QMainWindow *mw = qobject_cast<QMainWindow *>(parentWidget()); if (mw && mw->layout()) { QLayout *layout = mw->layout(); int i = 0; QLayoutItem *item = 0; do { item = layout->itemAt(i++); if (item && (item->widget() == this)) sz = mw->iconSize(); } while (!sz.isValid() && item != 0); } } if (!sz.isValid()) { const int metric = style()->pixelMetric(QStyle::PM_ToolBarIconSize, 0, this); sz = QSize(metric, metric); } if (d->iconSize != sz) { d->iconSize = sz; setMinimumSize(0, 0); emit iconSizeChanged(d->iconSize); } d->explicitIconSize = iconSize.isValid(); d->layout->invalidate(); }