1 What is GraphPS ?

GraphPs is an Objective Caml library used to generate PostScript files from Caml graphics drawings.

GraphPs provides a module similar to the usual graphics drawings module Graphics of the regular Caml distribution. This module, also named Graphics, has (almost) the same signature as the original Graphics module. Thus, using the GraphPs Graphics module, your Caml drawing programs transparently generate PostScript files (that can be encapsulated into TeX or L^AT_EX files), instead of drawing graphics directly onto the screen.

2 Using GraphPS

Intended usage of this library could be seen as a three phases process:

write a regular Caml program (either batch or interactive) using the regular Graphics library.
use the GraphPS library instead of the regular Graphics library (for instance you can just change the Caml library load path to obtain linking of GraphPS in place of Graphics). Recompile your Caml program to obtain a new executable that produces PostScript commands instead of Graphics commands.
run the new executable to produce a PostScript file that exactly corresponds to the drawing produced by your Caml program.

A PostScript program corresponding to your Graphics sequence of commands is printed to the standard output of the program, when close_graph () is evaluated, or alternatively when the normal termination of the Caml program is reached. You can thus redirect the output to whichever file you want. GraphPS generates encapusulated PostScript files, which means that a so-called bounding box (that gives the size of the drawing) is calculated and inserted at the beginning of the PostScript file to help L^AT_EX to insert it into the document. Hence you should produce a .eps suffixed file.

3 Using the PostScript files produced by GraphPS

3.1 Direct visualization

You can visualize directly the files using any PostScript visualizers, for instance ghostview or gs or gv.

3.2 Including PostScript files into your L^AT_EX files

This is not exactly a GraphPS problem, but a simple example may help to solve this L^AT_EX problem.

A very simple way to include your caml_drawings.eps file, is as follows:

use the graphicx package of L^AT_EX, writing the following line into your L^AT_EX document:
```
\usepackage[dvips]{graphicx}
```
then order L^AT_EX to include the caml_drawings.eps file into the document by writing the line:
```
\includegraphics{caml_drawings.eps}
```

For instance, the following line will draw the drawings of the file euro.eps, centered in the current line.

\centerline{\includegraphics[width=10cm]{euro.eps}}

4 Trouble shooting

4.1 Caml problems

Most of the time, your original Caml program should work just fine with no modification when using the Graphics module provided by GraphPs.

However, some Graphics commands are not supported by the GraphPS library, since they have no meaning for PostScript files (e.g. mouse events handling commands). If the original program uses such commands, you should remove them.

4.2 PostScript problems

To ensure proper inclusion of generated PostScript files, GraphPS does not add any showpage order at the end of the file.

If you want to send the produced PostScript file directly to a PostScript printer, you may be obliged to add a showpage order at the end of the file.

This document was translated from L^AT_EX by H^EV^EA.