6.4. Mapnik and Cairo Graphics
Mapnik does not only support using Cairo Graphics as a render backend for direct output, it can also be told to render into a cairo surface object. So it can be used to combine mapnik map output with other graphical elements generated by cairo graphics calls.
One example that makes use of this is MapOSMatic, which adds things like a map title, copyright and attribution footer, and an optional street index sidebar, around a mapnik generated map, or even creates multi page PDF books with one mapnik map rendered on each page.