GIMP Background

1. GIMP Background

One of the wonderful features of GIMP is that it all its functionality may be accessed through scripting. So far most of the script programming for Gimp has been done through Scheme through Script-Fu.

Perl as a language is probably more familiar to the web-literate users, as it is the major language for writing CGI scripts. Now, Gimp scripts may also be written with Perl. This tutorial will describe how to write such plug-ins and scripts for Gimp.

2. What you need

The Perl::Gimp tutorial scripts have been tested with the following versions:

1. Gimp version 1.2 or later, with all its prerequisites.
2. Perl version 5.005 or later.
3. The perl module Gtk, version 0.7003
4. The Gimp module, version 1.201 or later

Perl and all its associated modules are available in source form from the Perl Comprehensive Archive network, CPAN. It is also possible to download them in RPM format from the ftp.gimp.org website.

3. The Gimp module

Most scripts make use of the simplified interface Gimp::Fu provided with the Gimp module. Gimp::Fu provides a framework for entering parameters to the script in a frame like interface, just like Script-Fu, but also allows running of the script in batch mode from the command line. This tutorial will go into detail descriptions of the construction of a Gimp::Fu script, but before we do this, here is the general framework of a Perl-Fu script.

  1:  #!/usr/local/bin/perl 
  2:   
  3:  use Gimp ":auto"; 
  4:  use Gimp::Fu; 
  5:   
  6:  # Register extension to gimp 
  7:  register ... ; 
  8:       
  9:  exit main();  # Handle over control to gimp 

The interesting items to note in the script is the use of the two modules Gimp and Gimp::Fu, the register function, which will be described in detail below, and the way the control is handed over to Gimp module on line 9. The use of the ":auto" statement makes perl automatically include all of the gimp PDB functions and constants into the perl name space.