QPainter does not honor Qt::SmoothPixmapTransform render hint

When using a QPainter to draw a scaled image, the result is really poor even with the Qt::SmoothPixmapTransform render hint turned on. It looks like it does not make any difference is the hint is enabled or not.

Scaling with QImage::scaled(..., Qt::SmoothTransformation) first and then painting the scaled image results in a superior rendering.

I attached an example project that displays an image at it's original size (128x128) and then scaled down to 20x20 pixels via the painter and via QImage::scaled().