Function ncpile_render_to_buffer 

pub unsafe extern "C" fn ncpile_render_to_buffer(
    p: *mut ncplane,
    buf: *mut *mut c_char,
    buflen: *mut usize,
) -> c_int

Perform the rendering and rasterization portion of ncpile_render() and ncpile_rasterize(), but do not write the resulting buffer out to the terminal. Using this function, the user can control the writeout process. The returned buffer must be freed by the caller.