 GD InTpreter
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 the 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
-
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.
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.
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
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 gdlibrary
is ported to PNG it is hoped that gdit can be moved to this new standard without
too much difficulty.
Credits and license terms
gd 1.1.1 is copyright 1994, Quest Protein Database Center. You must obtain gd
separately from gdit. See the documentation for full terms.
gdit v1.4 is copyright 1995, David George and is based on v 1.2 of gd library.
Page Created: November 27, 1995 | 
