[cairo] Duplicate surface with different format

[Carlos López Camey]

Hi, new to the list here! Tried to search for this function in the
API/Google but no success.

I've a GtkDrawingArea and its surface has format CAIRO_FORMAT_INVALID
by _default_, i.e. "no such format exists or is supported" for that
surface's data. Is there a way to create a copy of my GtkDrawingArea
surface with any format I choose? Then I'd be able to query the data
knowing its format, I'm trying to get a coordinate RGBA values.

Thanks!