[cairo] cairo_surface_map_to_image () -- for what is it used?

[Stefan Salewski]

https://www.cairographics.org/manual/cairo-cairo-surface-t.html#cairo-surface-map-to-image

I was working yesterday on the cairo Nim high level wrapper and found this function.

After reading the doc page, I have still no idea what it is.

Can you give me a hint for what it may be used?

"most efficient mechanism" sounds interesting!