#!/usr/bin/perl -w

# Copyright © 2001 by Julian Fong <http://www.levork.org/>.  All rights reserved.
#
# Permission to use, copy, modify, distribute, and sell this software
# and its documentation for any purpose is hereby granted without fee,
# provided that the above copyright notice appear in all copies and
# that both that copyright notice and this permission notice appear in
# supporting documentation.  No representations are made about the
# suitability of this software for any purpose.  It is provided "as
# is" without express or implied warranty.
#
# giflet: create minimal 1x1 gifs for spacing in HTML documents

unless (@ARGV == 4) {
    die "Usage: giflet red green blue filename\n"
}
open (FILE, ">$ARGV[3]") || die "Unable to open $ARGV[3]: $!\n";
binmode (FILE);
syswrite (FILE, 
	  pack("a6vvCCCCCCCCCCvvvvCCCCCCC",
	       ("GIF87a"), 	# 0: signature
	       1,		# 6: width
	       1,		# 8: height
	       0200,		# 10: global color map exists, 
	       			#     1 bit of color res, 1 bit of pixel
	       0,		# 11: background index
	       0,		# 12: reserved
	       $ARGV[0],	# 13: global color map entries
	       $ARGV[1],
	       $ARGV[2],
	       0,		# 16: black
	       0,
	       0,
	       0054,		# 19: image separator character ','
	       0,		# 20: x pos
	       0,		# 22: y pos
	       1,		# 24: width
	       1,		# 26: height
	       0,		# 28: use global color map,
		                #     image in sequential order, 
		                #     BPP=1 bit
	       2,		# 29: Code size - number of bits needed
				#     to represent data, although this
		   		#     is one bit we must bump it to two
	       2,		# 30: Block byte count: two bytes follow
	       0104, 0001,	# 31: break into 3 bit words:
		   		#     100 clear code
				#     000 data
				#     101 clear code + 1 (End Of Information)
			        #     000.. padding
	       0,		# 33: zero byte count - terminate compression
	       0073		# 34: end character ';'
	      ),
	  35);
close(FILE);