Function fz_copy_rectangle 

pub unsafe extern "C" fn fz_copy_rectangle(
    ctx: *mut fz_context,
    page: *mut fz_stext_page,
    area: fz_rect,
    crlf: c_int,
) -> *mut c_char

Return a newly allocated UTF-8 string with the text for a given
selection rectangle.

crlf: If true, write “\r\n” style line endings (otherwise “\n”
only).