#!/usr/bin/perl 
#
# $Id: plot.gif,v 1.3 2001/12/11 13:47:36 matthew 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/cgi-bin/plot.gif
#
# http://www.lon-capa.org/
#
###########################################################################
#
# CGI-BIN interface to GD, used for making mathematical plots.
#
# User specifies the following variables (given are defaults):
#    height   = "100"
#    width    = "100"
#    xmin     = "-10.0"
#    xmax     = " 10.0"
#    ymin     = "-10.0"
#    ymax     = " 10.0"
#    transparent   (doesn't work with gif?)
#    frame    
#    drawaxes 
#    drawtics 
#    vtic_every = "1.0"
#    htic_every = "1.0"
#    xseries1  = "x1,x2,x3,x4,x5,...,xn"
#    yseries1  = "y1,y2,y3,y4,y5,...,yn"
#    xseries2  = ..
#    yseries2  = ..
#    ...
#    label1 = "x,y,size,text"
#    label2 = "x,y,size,text"
#    label3 = "x,y,size,text"
#    ...
#
#    size of a labelN is one of :
#       giant, large, medium, small, tiny
#
###########################################################################
use GD;

my @inputs = split(/&/,$ENV{'QUERY_STRING'});
foreach $input (@inputs) {
    ($var,$val) = split /\=/,$input,2;
    if (! defined($val)) {
	$val = 1;
    }
    $In{lc($var)}=$val;
}

$height = &grab('height',100,\%In);
$width  = &grab('width',100,\%In);
$axis->{'xmin'} = &grab('xmin',-10,\%In);
$axis->{'xmax'} = &grab('xmax', 10,\%In);
$axis->{'ymin'} = &grab('ymin',-10,\%In);
$axis->{'ymax'} = &grab('ymax', 10,\%In);
$axis->{'xlen'} = $axis->{'xmax'} - $axis->{'xmin'};
$axis->{'ylen'} = $axis->{'ymax'} - $axis->{'ymin'};
$vtic_every = &grab('vtic_every',1.0,\%In);
$htic_every = &grab('htic_every',1.0,\%In);

my $image = new GD::Image($width,$height);

# allocate standard colors
my @BGvalues = split /,/,&grab('bgcolor','255,255,255',\%In);
my @FGvalues = split /,/,&grab('fgcolor','0,0,0',\%In);
my $bgcolor = $image->colorAllocate(@BGvalues);
my $fgcolor = $image->colorAllocate(@FGvalues);       

# Draw a fgcolor frame around the picture
&drawtics($htic_every,$vtic_every) if (exists($In{'drawtics'}));
&drawaxes($axis)                   if (exists($In{'drawaxis'}));
&drawframe(1)                          if (exists($In{'frame'}));
# make the background transparent if needed (this doesn't work, at least
# not for gif images, don't know if it works for png)
$image->transparent($bgcolor)       if (exists($In{'transparent'}));

## Take care of labels and data series
foreach (keys %In) {
    if (/^label/) {
	my ($x,$y,$size,$text) = split/,/,$In{$_};
	&drawstring($text,$x,$y,$fgcolor,$size);
	delete ($In{$_});
	next;
    } elsif (/^xseries/) {
	$xname = $_;
	$yname = $xname;
	$yname =~ s/^x/y/;
	(@X)=split/,/,$In{$xname};
	(@Y)=split/,/,$In{$yname};
	delete ($In{$xname});
	delete ($In{$yname});	
	if ($#X != $#Y) {
	    &drawstring("size of $xname and $yname do not match",
		       10,10,$fgcolor,"giant");
	    next;
	}
	&drawcurve(\@X,\@Y);
    }
}


# Tell the browser our mime-type
print <<END;
Content-type: image/gif

END

my $BinaryData=$image->png;
undef $image;
binmode(STDOUT);
open IMG,"|pngtopnm|ppmtogif 2>/dev/null"; # convert into a gif image
print IMG $BinaryData; # output image
$|=1;                  # be sure to flush before closing
close IMG;


#--------------------------------------------------------------------

sub grab{
    my ($name,$default,$h) = @_;
    my $value = $h->{$name};
    if (defined($value)) {
	delete ($h->{$name}) ;
    } else {
	$value = $default;
    }
    return $value;
}

# transformPoint(x,y) where x,y are in the coordinates of axis will return
# the coordinates transformed to the image coordinate system.
sub transformPoint{
    my ($x,$y) = @_;
    my ($width,$height) = $image->getBounds();
    $x = ( $x - $axis->{"xmin"}) * $width / ( $axis->{"xlen"});
    $y = ( ( $axis->{"ylen"} ) - ($y - $axis->{"ymin"})) 
	* $height / ( $axis->{"ylen"} );
    return($x,$y);
}

sub drawaxes{
    ($x1,$y1) = &transformPoint($axis->{"xmin"},0,$image,$axis);
    ($x2,$y2) = &transformPoint($axis->{"xmax"},0,$image,$axis);
    $image->line($x1,$y1,$x2,$y2,$fgcolor);
    ($x1,$y1) = &transformPoint(0,$axis->{"ymin"},$image,$axis);
    ($x2,$y2) = &transformPoint(0,$axis->{"ymax"},$image,$axis);
    $image->line($x1,$y1,$x2,$y2,$fgcolor);
}

sub drawtics{
    my ($htic_every,$vtic_every) = @_;
    my ($width,$height) = $image->getBounds();
    
    $ticwidth  = ($width  > 99 ? 5 : int($width /20) + 1);
    $ticheight = ($height > 99 ? 5 : int($height/20) + 1);

    # Do tics along y-axis
    for ($ntic = 0; $ntic <=int($axis->{"ylen"}/$vtic_every); $ntic++){
	my ($x1,$y1) = &transformPoint(0,$axis->{"ymin"}+$ntic*$vtic_every);
	my ($x2,$y2) = &transformPoint(0,$axis->{"ymin"}+$ntic*$vtic_every);
	$x1 -= $ticwidth;
	$x2 += $ticwidth;
	$image->line($x1,$y1,$x2,$y2,$fgcolor);
    }
    # Do tics along x-axis
    for ($ntic = 0; $ntic <=int($axis->{"xlen"}/$htic_every); $ntic++){
	my ($x1,$y1) = &transformPoint( $axis->{"xmin"}+$ntic*$htic_every,0);
	my ($x2,$y2) = &transformPoint( $axis->{"xmin"}+$ntic*$htic_every,0);
	$y1 -= $ticheight;
	$y2 += $ticheight;
	$image->line($x1,$y1,$x2,$y2,$fgcolor);
    }
}

sub drawcurve{
    my ($X,$Y) = @_;
    for($i=0;$i< (@$X-1);$i++) {
	($x1,$y1) = &transformPoint($X->[$i  ],$Y->[$i  ]);
	($x2,$y2) = &transformPoint($X->[$i+1],$Y->[$i+1]);
	$image->line($x1,$y1,$x2,$y2,$fgcolor);
    }
}

sub drawframe{
    # Draw a frame around the picture.
    my ($xoffset,$yoffset) = @_;
    $xoffset = $xoffset || 1;
    $yoffset = $yoffset || $xoffset;
    my ($width,$height) = $image->getBounds();
    $image->rectangle($xoffset-1,$yoffset-1,$width-$xoffset,$height-$yoffset,$fgcolor);
}

sub drawstring{
    # Write some text on the image.
    my ($text,$x,$y,$color,$fontName) = @_;
    $font = gdGiantFont      if (lc($fontName) eq "giant" ||
				 lc($fontName) eq "huge"     );
    $font = gdLargeFont      if (lc($fontName) eq "large");
    $font = gdMediumBoldFont if (lc($fontName) eq "medium");
    $font = gdSmallFont      if (lc($fontName) eq "small");
    $font = gdTinyFont       if (lc($fontName) eq "tiny");
    if (! defined($font)) {
	$font = gdGiantFont;
	$text = "Font size error!";
    }
    ($x,$y) = &transformPoint($x,$y);
    $image->string($font,$x,$y,$text,$color);
}