cairo: multiple sprites images in one PNG

[Christopher Howard <christopher howard frigidcode com>]

Question for the veterans:

I'm coding a simple space combat game with GTK+. For the sprites, I know
I can do this to draw:

code:
----------
ship_surf = cairo_image_surface_create_from_png("ship.png");
// ...
cairo_set_source_surface (cr, ship_surf, x, y);
cairo_paint (cr);
----------

But what if I want, for ease of maintainability (and less system I/O
calls) to put a whole bunch of sprites in one PNG? Is it possible for me
to either...

* load one PNG image into a surface, and then draw to a CR using only a
small part of that surface?

or

* load one PNG into a surface, and then split that surface into multiple
smaller surfaces?

It wasn't quite clear to me from the documentation how to go about this.

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