This page lets you enter PDF graphics commands and see the result by wrapping them in a complete PDF file with one A4 page (595 by 842 pt). All PDF commands permitted in a content stream can be used, except those which require external objects such as patterns and non-standard fonts.
Standard fonts are named as follows: /FC /FCo /FCb /FCbo /FH /FHo /FHb /FHbo /FT /FTi /FTb /FTbi /FS /FZ, where C=Courier, H=Helvetica, T=Times, S=Symbol, Z=Zapf Dingbats, b=bold, o=oblique, i=italic.
Interested in a C library to do that and much more? NPW is here!