The png package
does include libpng: here is the packing list:
Code:
@comment $OpenBSD: PLIST,v 1.22 2007/10/06 19:33:28 naddy Exp $
%%SHARED%%
bin/libpng-config
include/libpng/
include/libpng/png.h
include/libpng/pngconf.h
lib/libpng.a
lib/pkgconfig/
lib/pkgconfig/libpng.pc
@endfake
@man man/cat3/libpng.0
@man man/cat3/libpngpf.0
@man man/cat5/png.0
share/doc/png/
share/doc/png/libpng-${VERSION}.txt
You can see exactly what files are installed in your system when you did the pkg_add, just issue $ pkg_info -L png