The useHardwareStretching property tells, whether to let the graphics card stretch the image to widget size or to do this in software mode.
In hardware mode the resulting texture has the size of the original image. This may be smaller than the actual widget size,
which results in smaller memory footprint and possibly better rendering performance.
On the down side the graphics card may not scale the image as nicely as in software mode.
In software mode (the default) the resulting texture has exactly widget size and takes that much memory. In software mode we can do as much as we can to scale the image in highest quality.