Qt中带有圆角和PreserveAspectFit的图像

QPixmap pixmap("image.jpg");

QPainter painter;
painter.begin(&pixmap);
painter.setRenderHint(QPainter::Antialiasing); // 开启抗锯齿

QRectF rect(0, 0, pixmap.width(), pixmap.height());
int radius = 10; // 圆角半径
painter.drawRoundedRect(rect, radius, radius);

QRectF targetRect(0, 0, pixmap.width(), pixmap.height());
QRectF sourceRect = pixmap.rect();
sourceRect.setSize(sourceRect.size().scaled(targetRect.size(), Qt::KeepAspectRatio));
sourceRect.moveCenter(targetRect.center());
painter.drawPixmap(targetRect, pixmap, sourceRect.toRect());

painter.end();