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Bug 2587 (Imageresponse does not generate eps file on print for students) is fixed. This bug is due to the change in the path to dynamically produced eps pictures (now it is full, not only eps file in /home/httpd/prtspool). I've implemented changes in londefdef.pm for static pictures and in randomlabel.pm for randomlab. pictures but has forgotten about imageresponse.pm. Now seem to me everything is fine.

# The LearningOnline Network with CAPA
# image click response style
#
# $Id: imageresponse.pm,v 1.45 2004/01/15 19:51:30 sakharuk Exp $
#
# Copyright Michigan State University Board of Trustees
#
# This file is part of the LearningOnline Network with CAPA (LON-CAPA).
#
# LON-CAPA is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# LON-CAPA 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.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with LON-CAPA; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# /home/httpd/html/adm/gpl.txt
#
# http://www.lon-capa.org/
#
#FIXME LATER assumes multiple possible submissions but only one is possible 
#currently

package Apache::imageresponse;
use strict;
use Image::Magick;
use Apache::randomlylabel;
use Apache::Constants qw(:common :http);

BEGIN {
    &Apache::lonxml::register('Apache::imageresponse',('imageresponse'));
}

sub start_imageresponse {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result;
    #when in a radiobutton response use these
    &Apache::lonxml::register('Apache::imageresponse',
			      ('foilgroup','foil','text','image','rectangle',
			       'polygon','conceptgroup'));
    push (@Apache::lonxml::namespace,'imageresponse');
    my $id = &Apache::response::start_response($parstack,$safeeval);
    if ($target eq 'meta') {
	$result=&Apache::response::meta_package_write('imageresponse');
    } elsif ($target eq 'analyze') {
	my $part_id="$Apache::inputtags::part.$id";
	push (@{ $Apache::lonhomework::analyze{"parts"} },$part_id);
    }
    return $result;
}

sub end_imageresponse {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    &Apache::response::end_response;
    pop @Apache::lonxml::namespace;
    &Apache::lonxml::deregister('Apache::imageresponse',('foilgroup','foil','text','image','rectangle','conceptgroup'));
    my $result;
    if ($target eq 'edit') { $result=&Apache::edit::end_table(); }
    return $result;
}

%Apache::response::foilgroup=();
sub start_foilgroup {
    %Apache::response::foilgroup=();
    $Apache::imageresponse::conceptgroup=0;
    &Apache::response::setrandomnumber();
    return '';
}

sub getfoilcounts {
    my ($parstack,$safeeval)=@_;

    my $max = &Apache::lonxml::get_param('max',$parstack,$safeeval,'-2');
    # +1 since instructors will count from 1
    my $count = $#{ $Apache::response::foilgroup{'names'} }+1;
    if (&Apache::response::showallfoils()) { $max=$count; }
    return ($count,$max);
}

sub whichfoils {
    my ($max)=@_;
    if (!defined(@{ $Apache::response::foilgroup{'names'} })) { return; }
    my @names = @{ $Apache::response::foilgroup{'names'} };
    my @whichopt =();
    while ((($#whichopt+1) < $max) && ($#names > -1)) {
	&Apache::lonxml::debug("Have $#whichopt max is $max");
	my $aopt;
	if (&Apache::response::showallfoils()) {
	    $aopt=0;
	} else {
	    $aopt=int(&Math::Random::random_uniform() * ($#names+1));
	}
	&Apache::lonxml::debug("From $#names elms, picking $aopt");
	$aopt=splice(@names,$aopt,1);
	&Apache::lonxml::debug("Picked $aopt");
	push (@whichopt,$aopt);
    }
    return @whichopt;
}

sub prep_image {
    my ($image,$mode,$name)=@_;
    my $part=$Apache::inputtags::part;
    my $respid=$Apache::inputtags::response['-1'];
    my $id=&Apache::loncommon::get_cgi_id();
    my %x;
    $x{"cgi.$id.BGIMG"}=$image;
    my ($x,$y)=split(/:/,$Apache::lonhomework::history{"resource.$part.$respid.submission"});
    #draws 2 xs on the image at the clicked location
    #one in white and then one in red on top of the one in white
    if (defined($x) && defined($y)) {
	$x{"cgi.$id.LINECOUNT"}=4;
	my $length = 6;
	my $width = 1;
	my $extrawidth = 2;
	$x{"cgi.$id.LINE0"}=
	    join(':',(($x-$length),($y-$length),($x+$length),($y+$length),
		      "FFFFFF",($width+$extrawidth)));
	$x{"cgi.$id.LINE1"}=
	    join(':',(($x-$length),($y+$length),($x+$length),($y-$length),
		      "FFFFFF",($width+$extrawidth)));
	$x{"cgi.$id.LINE2"}=
	    join(':',(($x-$length),($y-$length),($x+$length),($y+$length),
		      "FF0000",($width)));
	$x{"cgi.$id.LINE3"}=
	    join(':',(($x-$length),($y+$length),($x+$length),($y-$length),
		      "FF0000",($width)));
    }
    if ($mode eq 'answer') {
	my $width = 1;
	my $extrawidth = 2;
	my @areas = @{ $Apache::response::foilgroup{"$name.area"} };
	foreach my $area (@areas) {
	    if ($area=~/^rectangle:/) {
		my ($x1,$y1,$x2,$y2)=
		    ($area=~m/rectangle:\(([0-9]+),([0-9]+)\)\-\(([0-9]+),([0-9]+)\)/);
		my $i=$x{"cgi.$id.BOXCOUNT"}++;
		$x{"cgi.$id.BOX$i"}=join(':',($x1,$y1,$x2,$y2,"FFFFFF",
					      ($width+$extrawidth)));
		$i=$x{"cgi.$id.BOXCOUNT"}++;
		$x{"cgi.$id.BOX$i"}=join(':',($x1,$y1,$x2,$y2,"00FF00",$width));
	    } elsif ($area=~/^polygon:(.*)/) {
		my $i=$x{"cgi.$id.POLYCOUNT"}++;
		$x{"cgi.$id.POLYOPT$i"}=join(':',("FFFFFF",($width+$extrawidth)));
		$x{"cgi.$id.POLY$i"}=$1;
		$i=$x{"cgi.$id.POLYCOUNT"}++;
		$x{"cgi.$id.POLYOPT$i"}=join(':',("00FF00",$width));
		$x{"cgi.$id.POLY$i"}=$1;
	    }
	}
    }
    &Apache::lonnet::appenv(%x);
    return $id;
}

sub displayfoils {
    my ($target,@whichopt) = @_;
    my $result ='';
    my $name;
    my $temp=1;
    foreach $name (@whichopt) {
	$result.=$Apache::response::foilgroup{"$name.text"};
	&Apache::lonxml::debug("Text is $result");
	if ($target eq 'tex') {$result.="\\vskip 0 mm \n";} else {$result.="<br />\n";}
	my $image=$Apache::response::foilgroup{"$name.image"};
	&Apache::lonxml::debug("image is $image");
	if ( $target eq 'web' && $image !~ /^http:/ ) {
	    $image=&Apache::lonnet::filelocation($Apache::lonxml::pwd[-1],$image);
	    if (&Apache::lonnet::repcopy($image) ne OK) {
		$image='/home/httpd/html/adm/lonKaputt/lonlogo_broken.gif';
	    }
	}
	&Apache::lonxml::debug("image is $image");
	if ( &Apache::response::show_answer() ) {
	    if ($target eq 'tex') {
		$result.=$Apache::response::foilgroup{"$name.image"}."\\vskip 0 mm \n";
	    } else {
		my $token=&prep_image($image,'answer',$name);
		$result.="<img src=\"/adm/randomlabel.png?token=$token\" /><br />\n";
	    }
	} else {
	    if ($target eq 'tex') {
		$result.=$Apache::response::foilgroup{"$name.image"}."\\vskip 0 mm \n";
	    } else {
		my $id=$Apache::inputtags::response['-1'];
		my $token=&prep_image($image);
		my $temp=1;
		$result.="<input type=\"image\" name=\"HWVAL_$id:$temp\" ".
		    "src=\"/adm/randomlabel.png?token=$token\" /><br />\n";
	    }
	}
	$temp++;
    }
    return $result;
}

sub gradefoils {
    my (@whichopt) = @_;
    my $x;
    my $y;
    my $result;
    my $id=$Apache::inputtags::response['-1'];
    my $temp=1;
    foreach my $name (@whichopt) {
	$x=$ENV{"form.HWVAL_$id:$temp.x"};
	$y=$ENV{"form.HWVAL_$id:$temp.y"};
	&Apache::lonxml::debug("Got a x of $x and a y of $y for $name");
	if (defined($x) && defined($y) &&
	    defined(@{ $Apache::response::foilgroup{"$name.area"} })) {
	    my @areas = @{ $Apache::response::foilgroup{"$name.area"} };
	    my $grade="INCORRECT";
	    foreach my $area (@areas) {
		&Apache::lonxml::debug("Area is $area for $name");
		$area =~ m/([a-z]*):/;
		&Apache::lonxml::debug("Area of type $1");
		if ($1 eq 'rectangle') {
		    $grade=&grade_rectangle($area,$x,$y);
		} elsif ($1 eq 'polygon') {
		    $grade=&grade_polygon($area,$x,$y);
		} else {
		    &Apache::lonxml::error("Unknown area style $area");
		}
		&Apache::lonxml::debug("Area said $grade");
		if ($grade eq 'APPROX_ANS') { last; }
	    }
	    &Apache::lonxml::debug("Foil was $grade");
	    if ($grade eq 'INCORRECT') { $result= 'INCORRECT'; }
	    if (($grade eq 'APPROX_ANS') && ($result ne 'APPROX_ANS')) { $result=$grade; }
	    &Apache::lonxml::debug("Question is $result");
	    $temp++;
	}
    }
    $Apache::lonhomework::results{"resource.$Apache::inputtags::part.$id.submission"}="$x:$y";
    $Apache::lonhomework::results{"resource.$Apache::inputtags::part.$id.awarddetail"}=$result;
    return '';
}

sub end_foilgroup {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result='';
    my @whichopt;
    if ($target eq 'web' || $target eq 'grade' || $target eq 'tex' ||
	$target eq 'analyze') {
	my ($count,$max) = &getfoilcounts($parstack,$safeeval);
	if ($count>$max) { $count=$max }
	&Apache::lonxml::debug("Count is $count from $max");
	@whichopt = &whichfoils($max);
	if ($target eq 'web' || $target eq 'tex') {
	    $result=&displayfoils($target,@whichopt);
	} elsif ($target eq 'grade') {
	    if ( defined $ENV{'form.submitted'}) { &gradefoils(@whichopt); }
	} elsif ( $target eq 'analyze') {
	    &Apache::response::analyze_store_foilgroup(\@whichopt,
						      ['text','image','area']);
	}
    } elsif ($target eq 'edit') {
	$result=&Apache::edit::end_table();
    }
    return $result;
}

sub start_conceptgroup {
    $Apache::imageresponse::conceptgroup=1;
    %Apache::response::conceptgroup=();
    return '';
}

sub end_conceptgroup {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    $Apache::imageresponse::conceptgroup=0;
    my $result;
    if ($target eq 'web' || $target eq 'grade' || $target eq 'tex' ||
	$target eq 'analyze') {
	&Apache::response::pick_foil_for_concept($target,
						 ['area','text','image'],
						 \%Apache::hint::image,
						 $parstack,$safeeval);
    } elsif ($target eq 'edit') {
	$result=&Apache::edit::end_table();
    }
    return $result;
}

sub insert_foil {
    return '
       <foil>
           <image></image>
           <text></text>
           <rectangle></rectangle>
       </foil>
';
}

$Apache::imageresponse::curname='';
sub start_foil {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    if ($target eq 'web' || $target eq 'grade' || $target eq 'tex' ||
	$target eq 'analyze') {
	my $name = &Apache::lonxml::get_param('name',$parstack,$safeeval);
	if ($name eq '') { $name=$Apache::lonxml::curdepth; }
	if ( $Apache::imageresponse::conceptgroup
	     && !&Apache::response::showallfoils()) {
	    push(@{ $Apache::response::conceptgroup{'names'} }, $name);
	} else {
	    push(@{ $Apache::response::foilgroup{'names'} }, $name);
	}
	$Apache::imageresponse::curname=$name;
    }
    return '';
}

sub end_foil {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result;
    if ($target eq 'edit') {
	$result=&Apache::edit::end_table();
    }
    return $result;
}

sub start_text {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result='';
    if ($target eq 'web' || $target eq 'tex' || $target eq 'analyze') { 
	&Apache::lonxml::startredirection; 
    } elsif ($target eq 'edit') {
	my $descr=&Apache::lonxml::get_all_text('/text',$parser);
	$result=&Apache::edit::tag_start($target,$token,'Task Description').
	    &Apache::edit::editfield($token->[1],$descr,'Text',60,2).
	    &Apache::edit::end_row();
    } elsif ($target eq "modified") {
	$result=$token->[4].&Apache::edit::modifiedfield('/text',$parser);
    }
    return $result;
}

sub end_text {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result;
    if ($target eq 'web' || $target eq 'tex' || $target eq 'analyze') {
	my $name = $Apache::imageresponse::curname;
	if ( $Apache::imageresponse::conceptgroup
	     && !&Apache::response::showallfoils() ) {
	    $Apache::response::conceptgroup{"$name.text"} = &Apache::lonxml::endredirection;
	} else {
	    $Apache::response::foilgroup{"$name.text"} = &Apache::lonxml::endredirection;
	}
    } elsif ($target eq 'edit') {
	$result=&Apache::edit::end_table();
    }
    return $result;
}

sub start_image {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result='';
    if ($target eq 'web' || $target eq 'tex' || $target eq 'analyze') { 
	&Apache::lonxml::startredirection; 
    } elsif ($target eq 'edit') {
	my $bgimg=&Apache::lonxml::get_all_text('/image',$parser);
	$Apache::edit::bgimgsrc=$bgimg;
	$Apache::edit::bgimgsrcdepth=$Apache::lonxml::curdepth;

	$result=&Apache::edit::tag_start($target,$token,'Clickable Image').
	    &Apache::edit::editline($token->[1],$bgimg,'Image Source File',40);
	$result.=&Apache::edit::browse(undef,'textnode').' ';
	$result.=&Apache::edit::search(undef,'textnode').
	    &Apache::edit::end_row();
    } elsif ($target eq "modified") {
	$result=$token->[4].&Apache::edit::modifiedfield('/image',$parser);
    }
    return $result;
}

sub end_image {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result;
    my $name = $Apache::imageresponse::curname;
    if ($target eq 'web') {
	my $image = &Apache::lonxml::endredirection;
	&Apache::lonxml::debug("original image is $image");
	if ( $Apache::imageresponse::conceptgroup
	     && !&Apache::response::showallfoils()) {
	    $Apache::response::conceptgroup{"$name.image"} = $image;
	} else {
	    $Apache::response::foilgroup{"$name.image"} = $image;
	}
    } elsif ($target eq 'analyze') {
	my $image = &Apache::lonxml::endredirection;
	if ( $Apache::imageresponse::conceptgroup
	     && !&Apache::response::showallfoils()) {
	    $Apache::response::conceptgroup{"$name.image"} = $image;
	} else {
	    $Apache::response::foilgroup{"$name.image"} = $image;
	}
    } elsif ($target eq 'edit') {
	$result=&Apache::edit::end_table();
    } elsif ($target eq 'tex') {
	my $src = &Apache::lonxml::endredirection;
	$src=&Apache::lonnet::filelocation($Apache::lonxml::pwd[-1],$src);
	my $width_param = '';
	my $height_param = '';
	my $scaling = .3;
	my $image = Image::Magick->new;
	my $current_figure = $image->Read($src);
	$width_param = $image->Get('width') * $scaling;;
	$height_param = $image->Get('height') * $scaling;;
	undef $image;
	my $epssrc = $src;
	$epssrc =~ s/(\.gif|\.jpg)$/\.eps/i;
	if (not -e $epssrc) {
	    my $localfile = $epssrc;
	    $localfile =~ s/.*(\/res)/$1/;	
	    my $file;
	    my $path;	
	    if ($localfile =~ m!(.*)/([^/]*)$!) {
		$file = $2;
		$path = $1.'/'; 
	    }	
	    my $signal_eps = 0;
	    my @content_directory = &Apache::lonnet::dirlist($path);
	    for (my $iy=0;$iy<=$#content_directory;$iy++) {
		my @tempo_array = split(/&/,$content_directory[$iy]);
		$content_directory[$iy] = $tempo_array[0];
		if ($file eq $tempo_array[0]) {
		    $signal_eps = 1;
		    last;
		}
	    }
	    if ($signal_eps) {
		my $eps_file = &Apache::lonnet::getfile($localfile);
	    } else {
		$localfile = $src;
		$localfile =~ s/.*(\/res)/$1/;	
		my $as = &Apache::lonnet::getfile($src);		      
	    }
	}
	my $file;
	my $path;	
	if ($src =~ m!(.*)/([^/]*)$!) {
	    $file = $2;
	    $path = $1.'/'; 
	}
	my $newsrc = $src;
	$newsrc =~ s/(\.gif|\.jpg|\.jpeg)$/\.eps/i;
	$file=~s/(\.gif|\.jpg|\.jpeg)$/\.eps/i;
	#do we have any specified size of the picture?
	my $TeXwidth = &Apache::lonxml::get_param('TeXwidth',$parstack,$safeeval); 
	my $TeXheight = &Apache::lonxml::get_param('TeXheight',$parstack,$safeeval); 
	my $width = &Apache::lonxml::get_param('width',$parstack,$safeeval);
	if ($TeXwidth ne '') { 
	    $width_param = $TeXwidth; 
	} elsif ($TeXheight ne '') { 
	    $width_param = $TeXheight/$height_param*$width_param;
	} elsif ($width ne '') {
	    $width_param = $width*$scaling;      
	}
	#where can we find the picture?
	if (-e $newsrc) {
	    if ($path) {
		$Apache::response::foilgroup{"$name.image"} ='\vskip 0 mm \noindent\graphicspath{{'.$path.'}}\includegraphics[width='.$width_param.' mm]{'.$file.'} ';
	    }
	} else {
	    my $temp_file;
	    my $filename = "/home/httpd/prtspool/$ENV{'user.name'}_$ENV{'user.domain'}_printout.dat";
	    $temp_file = Apache::File->new('>>'.$filename); 
	    print $temp_file "$src\n";
	    $newsrc=~s/\/home\/httpd\/html\/res//;
	    $newsrc=~s/\/home\/([^\/]*)\/public_html\//\/$1\//;
	    $newsrc=~s/\/\.\//\//;
	    $newsrc=~s/\/([^\/]+)\.(ps|eps)/\//;
	    $Apache::response::foilgroup{"$name.image"} ='\vskip 0 mm \graphicspath{{/home/httpd/prtspool'.$newsrc.'}}\includegraphics[width='.$width_param.' mm]{'.$file.'} ';
	}
    } 
    return $result;
}

sub start_rectangle {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result='';
    if ($target eq 'web' || $target eq 'grade' || $target eq 'tex' ||
	$target eq 'analyze') { 
	&Apache::lonxml::startredirection; 
    } elsif ($target eq 'edit') {
	my $coords=&Apache::lonxml::get_all_text('/rectangle',$parser);
	$result=&Apache::edit::tag_start($target,$token,'Rectangle').
	    &Apache::edit::editline($token->[1],$coords,'Coordinate Pairs',40).
	    &Apache::edit::entercoord(undef,'textnode',undef,undef,'box').
	    &Apache::edit::end_row();
    } elsif ($target eq "modified") {
	&Apache::edit::deletecoorddata();
	$result=$token->[4].&Apache::edit::modifiedfield('/rectangle',$parser);
    }
    return $result;
}

sub grade_rectangle {
    my ($spec,$x,$y) = @_;
    &Apache::lonxml::debug("Spec is $spec");
    my ($x1,$y1,$x2,$y2)=($spec=~m/rectangle:\(([0-9]+),([0-9]+)\)\-\(([0-9]+),([0-9]+)\)/);
    &Apache::lonxml::debug("Point $x1,$y1,$x2,$y2");
    if ($x1 > $x2) { my $temp=$x1;$x1=$x2;$x2=$temp; }
    if ($y1 > $y2) { my $temp=$y1;$y1=$y2;$y2=$temp; }
    if (($x >= $x1) && ($x <= $x2) && ($y >= $y1) && ($y <= $y2)) {
	return 'APPROX_ANS';
    }
    return 'INCORRECT';
}

sub end_rectangle {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result;
    if ($target eq 'web' || $target eq 'grade' || $target eq 'tex' ||
	$target eq 'analyze') {
	my $name = $Apache::imageresponse::curname;
	my $area = &Apache::lonxml::endredirection;
	&Apache::lonxml::debug("out is $area for $name");
	if ( $Apache::imageresponse::conceptgroup
	     && !&Apache::response::showallfoils()) {
	    push @{ $Apache::response::conceptgroup{"$name.area"} },"rectangle:$area";
	} else {
	    push @{ $Apache::response::foilgroup{"$name.area"} },"rectangle:$area";
	}
    } elsif ($target eq 'edit') {
	$result=&Apache::edit::end_table();
    }
    return $result;
}

sub start_polygon {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result='';
    if ($target eq 'web' || $target eq 'grade' || $target eq 'tex' ||
	$target eq 'analyze') { 
	&Apache::lonxml::startredirection; 
    } elsif ($target eq 'edit') {
	my $coords=&Apache::lonxml::get_all_text('/polygon',$parser);
	$result=&Apache::edit::tag_start($target,$token,'Polygon').
	    &Apache::edit::editline($token->[1],$coords,'Coordinate list',40).
	    &Apache::edit::entercoord(undef,'textnode',undef,undef,'polygon').
	    &Apache::edit::end_row();
    } elsif ($target eq "modified") {
	$result=$token->[4].&Apache::edit::modifiedfield('/polygon',$parser);
    }
    return $result;
}

sub grade_polygon {
    my ($spec,$x,$y) = @_;
    &Apache::lonxml::debug("Spec is $spec");
    $spec=~s/^polygon://;
    my @polygon;
    foreach my $coord (split('-',$spec)) {
	my ($x,$y)=($coord=~m/\(([0-9]+),([0-9]+)\)/);
	&Apache::lonxml::debug("x $x y $y");
	push @polygon, {'x'=>$x,'y'=>$y};
    }
    #make end point start point
    push @polygon, $polygon[0];
    # cribbed from
    # http://geometryalgorithms.com/Archive/algorithm_0103/algorithm_0103.htm
    my $crossing = 0;    # the crossing number counter

    # loop through all edges of the polygon
    for (my $i=0; $i<$#polygon; $i++) {    # edge from V[i] to V[i+1]
	if ((($polygon[$i]->{'y'} <= $y)
	     && ($polygon[$i+1]->{'y'} > $y))    # an upward crossing
	    || 
	    (($polygon[$i]->{'y'} > $y) 
	     && ($polygon[$i+1]->{'y'} <= $y))) { # a downward crossing
	    # compute the actual edge-ray intersect x-coordinate
            my $vt = ($y - $polygon[$i]->{'y'}) 
		/ ($polygon[$i+1]->{'y'} - $polygon[$i]->{'y'});
            if ($x < $polygon[$i]->{'x'} + $vt * 
		($polygon[$i+1]->{'x'} - $polygon[$i]->{'x'})) { # x<intersect
                $crossing++;   # a valid crossing of y=P.y right of P.x
	    }
	}
    }

    # 0 if even (out), and 1 if odd (in)
    if ($crossing%2) {
	return 'APPROX_ANS';
    } else {
	return 'INCORRECT';
    }
}

sub end_polygon {
    my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
    my $result;
    if ($target eq 'web' || $target eq 'grade' || $target eq 'tex' ||
	$target eq 'analyze') {
	my $name = $Apache::imageresponse::curname;
	my $area = &Apache::lonxml::endredirection;
	&Apache::lonxml::debug("out is $area for $name");
	if ( $Apache::imageresponse::conceptgroup
	     && !&Apache::response::showallfoils()) {
	    push @{ $Apache::response::conceptgroup{"$name.area"} },"polygon:$area";
	} else {
	    push @{ $Apache::response::foilgroup{"$name.area"} },"polygon:$area";
	}
    } elsif ($target eq 'edit') {
	$result=&Apache::edit::end_table();
    }
    return $result;
}
1;
__END__