how to use the cache-to-disk feature in Wallpaper

[Benoit Jacob]

Hi,

I think Mandelbrot is a good candidate for cache-to-disk, however, how
do i enable this feature?

I did setUsingDiskCache(true); in the constructor, and I emit
renderCompleted once my image has finished rendering, but that doesn't
make any difference.

Thanks,
Benoit