toolBar->setIconSize(QSize(8, 8));
int extent;QStyle::PixelMetric metric;metric = QStyle::PM_SmallIconSize;extent = QApplication::style()->pixelMetric(metric);toolBar->setIconSize(QSize(extent, extent));
int QWindowsStyle::pixelMetric(PixelMetric pm, const QStyleOption *opt, const QWidget *widget) const{... case PM_ToolBarIconSize:// ret = 24; ret = 16; break;...}
MainWindow::MainWindow(){ setIconSize(QSize(16, 16));...}