GDIT - GD InTpreter, version 1.4

Description

gdit is a simple interpreter for Thomas Boutell 's gd library. It can be used in preference to a high level language such as 'C' or the tcl interface to gd. gd provides a set of functions for creating CompuServe GIF files. GIF is a native file format for Web browsers.

gdit Provides a useful set of features including:

The ability to refer to colors by name. There are a number predefined colors.
Named line styles. These are not dependent on GIF color indexes so work across images and with existing images.
The program can be used interactively or as part of a script. Warning messages and prompting are automatically turned off in this mode.
Hides much of the complexity of the gd library.

gdit is not a generalised drawing package. It is designed to be used in Web CGI scripts where there is a set of known geometric data to be plotted. It can also be used from the command line to perform such chores as identifying and setting background colors on transparent GIFs.

History

I wrote gdit over a few weeks in March/April 1995. I decided to use bison and flex because they seemed to provided the most powerful environment for building the front end. I also have them running on both my NeXT and NT machines. Unfortunately I have neither used these tools before nor do I have any proper documentation other than some course notes copied down in '85 during a Computer Science lecture. I therefore apologize to any true disciples and would be very open to incorporating improvements. Anyway the whole thing seems to work fine.

As is often the case, gdit started out as a quick hack to solve a small problem, this was version 0.9 and seemed like the idea might have a wider audience. This version is a complete redesign of the earlier program and supports most of the features of the gd library.

New Features for 1.4

Can write GIF File data to the standard output stream. See example PERL scripts for usage.
Support for reading X bitmap files.
Script and Image files can be supplied on the command line.
Allow comment strings to be written to GIF files.
Redesigned parser to cope with limitations of standard Unix Yacc and Lex generators.
Simplified language syntax.

Requirements

If you are building the UNIX version you will require the gd library . This must be obtained separately from gdit. gdit will build with the 'standard' UNIX yacc and lex tools. GNU provide versions of these tools called bison and flex. gdit is gnu preferred but 'yacc a son gui', as they say. The MS Windows 32 bit version is available as an .exe, no batteries required. This version was built using MSVC 2.0, you can also rebuild gdit.exe with the UNIX sources for gd library and gdit, you will require the GNU ports of bison and flex.

gdit has been built on Sun, Linux PC, Windows NT, Windows 95, AIX and SGI systems.

Mirror FTP Sites

You should be able to find GDIT in the United States at:

Use Archie if you have any problems locating a copy.

License Terms

gdit is copyright 1995, David Harvey-George. Permission is granted to copy and distribute this work provided that all copyright notices remain intact. That means you can put it on your FTP site or distribute it on CDROM or other media without charge.

Use: gdit is free for none commercial use. However neither gdit or gd library is in the public domain. Copyright is retained by each holder.

Warranty

This program is distributed in the hope that it will be useful but without any warranty, without even the implied warranty of merchantability or fitness for a particular purpose.

Limitations

gdit only supports 1 output image (the current image) and 1 brush and tile image.

Future

Add resize support
Add image copy support. Note that you can overlay a small image on a large area using the brush and set line brushed features.

eg:

set brush rook.gif

line 20 20 20 20 brushed

Given the legal difficulties surrounding GIF a new standard called PNG has been proposed. This is a 24 bit graphics format featuring a better compression algorithm but supporting useful GIF features such as interlacing and transparent colors. If the gd library is ported to PNG it is hoped that gdit can be moved to this new standard without too much difficulty.

Here's a selection of some of the Web sites that use GDIT:

Environmental Resources Information Network: Interactive species distribution reporting mapping and modelling using the World Wide Web.
The BBC Web Server: The BBC WWW server is devoted to information of interest to systematists and other biologists of the organismic kind.
Internet Statistics from UNIL: Graphs generated on-the-fly by gdit from local Internet usage statistics.
Dynamic Image Site: Perl script to generate randomly colored backgrounds etc.
Loadmon: Loadmon - a system load monitoring tool. Generates graphs of system load in real time using gdit
SEQSCAN: SEQSCAN was designed to allow remote users to obtain text and graphic results from a scan of up to 6000 base pairs of DNA sequence.
WWW and GIS Integration at the University of Florida: Pilot Project to Integrate WWW and GIS at the GeoPlan Center in Florida. Lots of map data plotted using gdit and other tools.

Credits and license terms

Home BRHome