#!/usr/bin/perl

use CGI;
use CGI::Session;
use GD;
use strict;

my $q=new CGI;
my $ses=CGI::Session->new('driver:File;serializer=Storable;id:MD5',$q->param('sid'),{Directory=>'/tmp'});

my $phase=$ses->param("phase") || die ("Invalid session");
$ses->param("phase",$phase+1) if ($phase<3);
my $x1=$ses->param('x1');
my $y1=$ses->param('y1');
my $image=GD::Image->newFromGif("logo.gif");
my $color = $image->colorResolve(0,0,0);
if ($phase==1) {
    for (my $i=0;$i<5;$i++) {
	$image->setPixel($x1-$i,$y1,$color);
	$image->setPixel($x1+$i,$y1,$color);
	$image->setPixel($x1,$y1-$i,$color);
	$image->setPixel($x1,$y1+$i,$color);
    }
} else {
    my $x2=$ses->param('x2');
    my $y2=$ses->param('y2');
    my $xLow=($x1<$x2?$x1:$x2);
    my $xHi=($x1>$x2?$x1:$x2);
    for (my $x=$xLow;$x<$xHi;$x++) {
	$image->setPixel($x,$y1,$color);
	$image->setPixel($x,$y2,$color);
    }
    my $yLow=($y1<$y2?$y1:$y2);
    my $yHi=($y1>$y2?$y1:$y2);
    for (my $y=$yLow;$y<$yHi;$y++) {
	$image->setPixel($x1,$y,$color);
	$image->setPixel($x2,$y,$color);
    }
}

my $pngdata=$image->png;
print $q->header('image/png');
binmode STDOUT;
print $pngdata;