--- loncom/xml/lonplot.pm	2008/06/03 10:49:00	1.145
+++ loncom/xml/lonplot.pm	2018/09/26 14:02:47	1.178
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # Dynamic plot
 #
-# $Id: lonplot.pm,v 1.145 2008/06/03 10:49:00 foxr Exp $
+# $Id: lonplot.pm,v 1.178 2018/09/26 14:02:47 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -26,6 +26,9 @@
 # http://www.lon-capa.org/
 #
 
+
+
+
 package Apache::lonplot;
 
 use strict;
@@ -57,6 +60,8 @@ BEGIN {
 }
 
 
+=pod
+
 ## 
 ## Description of data structures:
 ##
@@ -73,7 +78,7 @@ BEGIN {
 ##  align
 ##
 ##  @labels: $labels[$i] = \%label
-##           %label: text, xpos, ypos, justify
+##           %label: text, xpos, ypos, justify, rotate, zlayer
 ##
 ##  @curves: $curves[$i] = \%curve
 ##           %curve: name, linestyle, ( function | data )
@@ -88,14 +93,21 @@ BEGIN {
 ##                                                               ##
 ###################################################################
 
+=cut
+
 my $max_str_len = 50;    # if a label, title, xlabel, or ylabel text
                          # is longer than this, it will be truncated.
 
-my %linetypes =
+my %linetypes =			# For png use these linetypes.
     (
      solid          => 1,
      dashed         => 0
     );
+my %ps_linetypes = 		# For ps the line types are different!
+   (
+    solid          => 1,
+    dashed         => 7
+   );
 
 my %linestyles = 
     (
@@ -120,13 +132,22 @@ my $real_test      =
     sub {$_[0]=~s/\s+//g;$_[0]=~/^[+-]?\d*\.?\d*([eE][+-]\d+)?$/};
 my $pos_real_test  =
     sub {$_[0]=~s/\s+//g;$_[0]=~/^[+]?\d*\.?\d*([eE][+-]\d+)?$/};
-my $color_test     = sub {$_[0]=~s/\s+//g;$_[0]=~/^x[\da-fA-F]{6}$/};
+my $color_test;
+if ($version < 4.6) {
+    $color_test = sub {$_[0]=~s/\s+//g;$_[0]=~s/^\#/x/;$_[0]=~/^x[\da-fA-F]{6}$/};
+} else {
+    $color_test = sub {$_[0]=~s/\s+//g;$_[0]=~s/^x/#/;$_[0]=~/^\#[\da-fA-F]{6}$/};
+}
 my $onoff_test     = sub {$_[0]=~/^(on|off)$/};
 my $key_pos_test   = sub {$_[0]=~/^(top|bottom|right|left|outside|below| )+$/};
 my $sml_test       = sub {$_[0]=~/^(\d+|small|medium|large)$/};
 my $linestyle_test = sub {exists($linestyles{$_[0]})};
 my $words_test     = sub {$_[0]=~s/\s+/ /g;$_[0]=~/^([\w~!\@\#\$\%^&\*\(\)-=_\+\[\]\{\}:\;\'<>,\.\/\?\\]+ ?)+$/};
 
+my $arrowhead_test = sub{$_[0]=~/^(nohead|head|heads| )+$/};
+my $arrowstyle_test= sub{$_[0]=~/^(filled|empty|nofilled)+$/};
+my $degree_test  = sub{&$pos_real_test($_[0]) && ($_[0] <= 360.0)};
+
 ###################################################################
 ##                                                               ##
 ##                      Attribute metadata                       ##
@@ -169,14 +190,16 @@ my %gnuplot_defaults =
 	 test        => $color_test, 
 	 description => 'Background color of image (xffffff)',
 	 edit_type   => 'entry',
-	 size        => '10'
+	 size        => '10',
+         class       => 'colorchooser'
 	 },
      fgcolor      => {
 	 default     => 'x000000',
 	 test        => $color_test,
 	 description => 'Foreground color of image (x000000)',
 	 edit_type   => 'entry',
-	 size        => '10'
+	 size        => '10',
+         class       => 'colorchooser'
 	 },
      transparent  => {
 	 default     => 'off',
@@ -235,7 +258,7 @@ my %gnuplot_defaults =
 	 test        => sub {$_[0]=~/^(left|right|middle|center)$/},
 	 description => 'Alignment for image in HTML',
 	 edit_type   => 'choice',
-	 choices     => ['left','right','middle']
+	 choices     => ['left','right','middle','center']
 	 },
      texwidth     => {
          default     => '93',
@@ -398,7 +421,14 @@ my %label_defaults =
          description => 'Rotation of label (degrees)',
          edit_type   => 'entry',
          size        => '10',
-     }
+     },
+     zlayer => {
+         default => '',
+         test => sub {$_[0]=~/^(front|back)$/},
+         description => 'Z position of label',
+         edit_type   => 'choice',
+         choices     => ['front','back'], 
+     },
      );
 
 my @tic_edit_order = ('location','mirror','start','increment','end',
@@ -445,10 +475,16 @@ my %tic_defaults =
 	 description => 'Number of minor tics per major tic mark',
 	 edit_type   => 'entry',
 	 size        => '10'
-	 },         
+	 }, 
+     rotate => {
+	 default => 'off',
+	 test    => $onoff_test,
+	 description => 'Rotate tic label by 90 degrees if on',
+	 edit_type   => 'onoff'
+     }
      );
 
-my @axis_edit_order = ('color','xmin','xmax','ymin','ymax','xformat', 'yformat');
+my @axis_edit_order = ('color','xmin','xmax','ymin','ymax','xformat', 'yformat', 'xzero', 'yzero');
 my %axis_defaults = 
     (
      color   => {
@@ -456,7 +492,8 @@ my %axis_defaults =
 	 test => $color_test,
 	 description => 'Color of grid lines (x000000)',
 	 edit_type   => 'entry',
-	 size        => '10'
+	 size        => '10',
+         class       => 'colorchooser'
 	 },
      xmin      => {
 	 default => '-10.0',
@@ -488,7 +525,7 @@ my %axis_defaults =
         },
      xformat      => {
          default     => 'on',
-         test        => sub {$_[0]=~/^(on|off|\d+(f|F|e|E))$/},
+         test        => sub {$_[0]=~/^(on|off|\d+(f|F|e|E|P))$/},
          description => 'X-axis number formatting',
          edit_type   => 'choice',
          choices     => ['on', 'off', '2e', '2f'],
@@ -496,14 +533,33 @@ my %axis_defaults =
      yformat      => {
          default     => 'on',
          test        => sub {$_[0]=~/^(on|off|\d+(f|F|e|E))$/},
-         description => 'X-axis number formatting',
+         description => 'Y-axis number formatting',
          edit_type   => 'choice',
          choices     => ['on', 'off', '2e', '2f'],
          },
-
+     
+     xzero => {
+     	default => 'off',
+     	test	=> sub {$_[0]=~/^(off|line|thick-line|dotted)$/},
+     	description => 'Show x-zero (y=0) axis',
+     	edit_type  => 'choice',
+     	choices	=> ['off', 'line', 'thick-line', 'dotted'],
+     	},
+     
+     yzero => {
+     	default => 'off',
+     	test	=> sub {$_[0]=~/^(off|line|thick-line|dotted)$/},
+     	description => 'Show y-zero (x=0) axis',
+     	edit_type  => 'choice',
+     	choices	=> ['off', 'line', 'thick-line', 'dotted'],
+     	},
      );
 
-my @curve_edit_order = ('color','name','linestyle','linewidth','linetype','pointtype','pointsize','limit');
+
+my @curve_edit_order = ('color','name','linestyle','linewidth','linetype',
+			'pointtype','pointsize','limit', 'arrowhead', 'arrowstyle', 
+			'arrowlength', 'arrowangle', 'arrowbackangle'
+    );
 
 my %curve_defaults = 
     (
@@ -512,7 +568,8 @@ my %curve_defaults =
 	 test => $color_test,
 	 description => 'Color of curve (x000000)',
 	 edit_type   => 'entry',
-	 size        => '10'
+	 size        => '10',
+	 class       => 'colorchooser'
 	 },
      name      => {
 	 default => '',
@@ -563,6 +620,43 @@ my %curve_defaults =
          edit_type   => 'choice',
          choices     => ['above', 'below', 'closed','x1','x2','y1','y2']
          },
+     arrowhead => {
+         default     => 'head',
+	 test        => $arrowhead_test,
+	 description => 'Vector arrow head type',
+	 edit_type   => 'choice',
+	 choices     => ['nohead', 'head', 'heads']
+     },
+     arrowstyle => {
+	 default     => 'filled',
+	 test        => $arrowstyle_test,
+	 description => 'Vector arrow head style',
+	 edit_type   => 'choice',
+	 choices     => ['filled', 'empty', 'nofilled']
+     },
+     arrowlength => {
+	 default     => 0.02,
+	 test        => $pos_real_test,
+	 description => "Length of vector arrow (only applies to vector plots)",
+	 edit_type   => 'entry',
+	 size        => '5'
+     },
+     arrowangle  => {
+	default      => 10.0,
+	test         => $degree_test,
+	description  => 'Angle of arrow branches to arrow body (only applies to vector plots)',
+	edit_type    => 'entry',
+	size         => '5'
+     },
+
+     arrowbackangle => {
+	 default    => 90.0,
+	 test       => $degree_test,
+	 descripton => 'Angle of arrow back lines to branches.',
+	 edit_type  => 'entry',
+	 size       => '5'
+     }
+
      );
 
 ###################################################################
@@ -574,6 +668,8 @@ my %curve_defaults =
 undef %Apache::lonplot::plot;
 my (%key,%axis,$title,$xlabel,$ylabel,@labels,@curves,%xtics,%ytics);
 
+my $current_tics;		# Reference to the current tick hash
+
 sub start_gnuplot {
     undef(%Apache::lonplot::plot);   undef(%key);    undef(%axis);
     undef($title);  undef($xlabel); undef($ylabel);
@@ -598,7 +694,18 @@ sub start_gnuplot {
     } elsif ($target eq 'modified') {
 	my $constructtag=&Apache::edit::get_new_args
 	    ($token,$parstack,$safeeval,keys(%gnuplot_defaults));
+
 	if ($constructtag) {
+	    #
+	    # The color chooser does not prepent x to the color values
+	    # Do that here:
+	    #
+	    foreach my $attribute ('bgcolor', 'fgcolor') {
+		my $value = $token->[2]{$attribute};
+		if (defined $value && !($value =~ /^x/)) {
+		    $token->[2]{$attribute} = 'x' . $value;
+		}
+	    }
 	    $result = &Apache::edit::rebuild_tag($token);
 	}
     }
@@ -612,6 +719,8 @@ sub end_gnuplot {
 	('title','xlabel','ylabel','key','axis','label','curve'));
     my $result = '';
     my $randnumber;
+    my $tmpdir =LONCAPA::tempdir(); # Where temporary files live:
+
     # need to call rand everytime start_script would evaluate, as the
     # safe space rand number generator and the global rand generator 
     # are not separate
@@ -623,7 +732,6 @@ sub end_gnuplot {
 	&check_inputs(); # Make sure we have all the data we need
 	##
 	## Determine filename
-	my $tmpdir = '/home/httpd/perl/tmp/';
 	my $filename = $env{'user.name'}.'_'.$env{'user.domain'}.
 	    '_'.time.'_'.$$.$randnumber.'_plot';
 	## Write the plot description to the file
@@ -631,21 +739,33 @@ sub end_gnuplot {
 	$filename = &escape($filename);
 	## return image tag for the plot
 	if ($target eq 'web') {
-	    $result .= <<"ENDIMAGE";
-<img src    = "/cgi-bin/plot.$weboutputformat?file=$filename.data" 
-     width  = "$Apache::lonplot::plot{'width'}"
-     height = "$Apache::lonplot::plot{'height'}"
-     align  = "$Apache::lonplot::plot{'align'}"
-     alt    = "$Apache::lonplot::plot{'alttag'}" />
-ENDIMAGE
+            my $srcatt = "src=\"/cgi-bin/plot.$weboutputformat?file=$filename.data\"";
+            my $widthatt = "width=\"$Apache::lonplot::plot{'width'}\"";
+            my $heightatt = "height=\"$Apache::lonplot::plot{'height'}\"";
+            my $alignatt = "align=\"$Apache::lonplot::plot{'align'}\"";
+            my $altatt = "alt=\"$Apache::lonplot::plot{'alttag'}\"";
+            if ($Apache::lonplot::plot{'align'} eq 'center') {
+                $result .= '<div style="text-align:center">'.
+                    "<img $srcatt $widthatt $heightatt $altatt>".
+                    "</div>\n";
+
+            } else {
+                $result .= "<img $srcatt $widthatt $heightatt $alignatt $altatt>";
+            }
         } elsif ($target eq 'tex') {
 	    &Apache::lonxml::debug(" gnuplot wid = $Apache::lonplot::plot{'width'}");
 	    &Apache::lonxml::debug(" gnuplot ht  = $Apache::lonplot::plot{'height'}");
 	    #might be inside the safe space, register the URL for later
 	    &Apache::lonxml::register_ssi("/cgi-bin/plot.gif?file=$filename.data&output=eps");
 	    $result  = "%DYNAMICIMAGE:$Apache::lonplot::plot{'width'}:$Apache::lonplot::plot{'height'}:$Apache::lonplot::plot{'texwidth'}\n";
-	    $result .= '\graphicspath{{/home/httpd/perl/tmp/}}'."\n";
+	    $result .= '\graphicspath{{'.$tmpdir.'}}'."\n";
+            if ($Apache::lonplot::plot{'align'} eq 'center') {
+                $result .= '\begin{center}';
+            }
 	    $result .= '\includegraphics[width='.$Apache::lonplot::plot{'texwidth'}.' mm]{'.&unescape($filename).'.eps}';
+            if ($Apache::lonplot::plot{'align'} eq 'center') {
+                $result .= '\end{center}';
+            }
 	}
     } elsif ($target eq 'edit') {
 	$result.=&Apache::edit::tag_end($target,$token);
@@ -661,6 +781,8 @@ sub start_xtics {
     if ($target eq 'web' || $target eq 'tex') {
 	&get_attributes(\%xtics,\%tic_defaults,$parstack,$safeeval,
 		    $tagstack->[-1]);
+	$current_tics = \%xtics;
+	&Apache::lonxml::register('Apache::lonplot', 'tic');
     } elsif ($target eq 'edit') {
 	$result .= &Apache::edit::tag_start($target,$token,'xtics');
 	$result .= &edit_attributes($target,$token,\%tic_defaults,
@@ -679,6 +801,7 @@ sub end_xtics {
     my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
     my $result = '';
     if ($target eq 'web' || $target eq 'tex') {
+	&Apache::lonxml::deregister('Apache::lonplot', 'tic');
     } elsif ($target eq 'edit') {
 	$result.=&Apache::edit::tag_end($target,$token);
     }
@@ -692,6 +815,8 @@ sub start_ytics {
     if ($target eq 'web' || $target eq 'tex') {
 	&get_attributes(\%ytics,\%tic_defaults,$parstack,$safeeval,
 		    $tagstack->[-1]);
+	$current_tics = \%ytics;
+	&Apache::lonxml::register('Apache::lonplot', 'tic');
     } elsif ($target eq 'edit') {
 	$result .= &Apache::edit::tag_start($target,$token,'ytics');
 	$result .= &edit_attributes($target,$token,\%tic_defaults,
@@ -710,12 +835,55 @@ sub end_ytics {
     my ($target,$token,$tagstack,$parstack,$parser,$safeeval,$style)=@_;
     my $result = '';
     if ($target eq 'web' || $target eq 'tex') {
+	&Apache::lonxml::deregister('Apache::lonplot', 'tic');
     } elsif ($target eq 'edit') {
 	$result.=&Apache::edit::tag_end($target,$token);
     }
     return $result;
 }
 
+
+##----------------------------------------------------------------
+#
+#  Tic handling:
+#   The <tic> tag allows users to specify exact Tic positions and labels
+#   for each axis.  In this version we only support level 0 tics (major tic).
+#   Each tic has associated with it a position and a label
+#   $current_tics is a reference to the current tick description hash.
+#   We add elements to an array  in that has: ticspecs whose elements
+#   are 'pos' - the tick position and 'label' - the tic label.
+#
+
+
+sub start_tic {
+    my ($target, $token, $tagstack, $parstack, $parser, $safeeval, $style)  = @_;
+
+    my $result = '';
+    if ($target eq 'web' || $target eq 'tex') {
+	my $tic_location = &Apache::lonxml::get_param('location', $parstack, $safeeval);
+	my $tic_label    = &Apache::lonxml::get_all_text('/tic', $parser);
+
+	# Tic location must e a real:
+
+	if (!&$real_test($tic_location)) {
+	    &Apache::lonxml::warning("Tic location: $tic_location must be a real number");
+	} else {
+
+	    if (!defined  $current_tics->{'ticspecs'}) {
+		$current_tics->{'ticspecs'} = [];
+	    }
+	    my $ticspecs = $current_tics->{'ticspecs'};
+	    push (@$ticspecs, {'pos' => $tic_location, 'label' => $tic_label});
+	}
+    }
+
+    return $result;
+}
+
+sub end_tic {
+    return '';
+}
+
 ##-----------------------------------------------------------------font
 my %font_properties =
     (
@@ -757,6 +925,7 @@ sub get_font {
 	$selected_font = $font_properties{$Apache::lonplot::plot{'fontface'}};
     }
     if ($target eq 'tex' && defined($Apache::lonplot::plot{'texfont'})) {
+#	$selected_font = $font_properties{'classic'};
 	$size = $Apache::lonplot::plot{'texfont'};
     }
     return ($size, $selected_font);
@@ -1327,6 +1496,13 @@ sub start_curve {
 	my $constructtag=&Apache::edit::get_new_args
 	    ($token,$parstack,$safeeval,keys(%curve_defaults));
 	if ($constructtag) {
+	    #
+	    # Fix up the color attribute as jcolor does not prepend an x
+	    #
+	    my $value = $token->[2]{'color'};
+	    if (defined $value && !($value =~ /^x/)) {
+		$token->[2]{'color'} = 'x' . $value;
+	    }
 	    $result = &Apache::edit::rebuild_tag($token);
 	}
     }
@@ -1361,6 +1537,9 @@ sub start_function {
         my $function = &Apache::lonxml::get_all_text("/function",$parser,
 						     $style);
 	$function = &Apache::run::evaluate($function,$safeeval,$$parstack[-1]);
+        $function=~s/\^/\*\*/gs;
+	$function=~ s/^\s+//;	# Trim leading
+	$function=~ s/\s+$//;   # And trailing whitespace.
 	$curves[-1]->{'function'} = $function; 
     } elsif ($target eq 'edit') {
 	$result .= &Apache::edit::tag_start($target,$token,'Gnuplot compatible curve function');
@@ -1431,7 +1610,7 @@ sub start_data {
 	}
 	# complain if the number of data points is not the same as
 	# in previous sets of data.
-	if (($curves[-1]->{'data'}) && ($#data != $#{@{$curves[-1]->{'data'}->[0]}})){
+	if (($curves[-1]->{'data'}) && ($#data != $#{$curves[-1]->{'data'}->[0]})){
 	    &Apache::lonxml::warning
 		('Number of data points is not consistent with previous '.
 		 'number of data points');
@@ -1472,7 +1651,17 @@ sub start_axis {
     } elsif ($target eq 'modified') {
 	my $constructtag=&Apache::edit::get_new_args
 	    ($token,$parstack,$safeeval,keys(%axis_defaults));
+
 	if ($constructtag) {
+	    #
+	    #  Fix up the color attribute since jchooser does not
+	    #  prepend an x to the color:
+	    #
+	    my $value = $token->[2]{'color'};
+	    if (defined $value && !($value =~ /^x/)) {
+		$token->[2]{'color'} = 'x' . $value;
+	    }
+
 	    $result = &Apache::edit::rebuild_tag($token);
 	}
     }
@@ -1530,6 +1719,65 @@ sub get_attributes{
     }
     return ;
 }
+##
+# Generate tic mark specifications.
+# 
+# @param type - type of tics (xtics or ytics).
+# @param spec - Reference to a hash that contains the tic specification.
+# @param target - 'tex' if hard copy target.
+#
+# @return string - the tic specification command.
+#
+sub generate_tics {
+    my ($type, $spec, $target) = @_;
+    my $result   = '';
+
+
+    if ((ref($spec) eq 'HASH') && (keys(%{$spec}) > 0)) {
+
+	
+
+	# Major tics: - If there are 'ticspecs' these override any other
+	#               specifications:
+
+	
+	
+	$result .= "set $type $spec->{'location'}  ";
+	$result .= ($spec->{'mirror'} eq 'on') ? 'mirror ' : 'nomirror ';
+	if ($spec->{'rotate'} eq 'on') {
+	    $result .= ' rotate ';
+	}
+	if (defined $spec->{'ticspecs'}) {
+	    $result .= '( ';
+	    my @ticspecs;
+	    my $ticinfo = $spec->{'ticspecs'};
+	    foreach my $tic (@$ticinfo) {
+		push(@ticspecs,  '"' . $tic->{'label'} . '" ' . $tic->{'pos'} );
+	    }
+	    $result .= join(', ', (@ticspecs));
+	    $result .= ' )';
+	} else {
+	    $result .= "$spec->{'start'}, ";
+	    $result .= "$spec->{'increment'}, ";
+	    $result .= "$spec->{'end'} ";
+	}
+	if ($target eq 'tex' ) {
+	    $result .= 'font "Helvetica,22"';
+	}
+	$result .= "\n";
+	
+	# minor frequency:
+	
+	if ($spec->{'minorfreq'} != 0) {
+	    $result .= "set m$type $spec->{'minorfreq'}\n";
+	}
+    } elsif ($target eq 'tex' ) {
+	$result .= "set $type font " . '"Helvetica,22"' ."\n";
+    }
+    
+    
+    return $result;
+}
 
 ##------------------------------------------------------- write_gnuplot_file
 sub write_gnuplot_file {
@@ -1565,6 +1813,7 @@ sub write_gnuplot_file {
 		       $curve->{'color'}       : 
 		       $Apache::lonplot::plot{'fgcolor'}        );
     }
+    
     # set term
     if ($target eq 'web') {
 	$gnuplot_input .= 'set terminal png enhanced nocrop ';
@@ -1577,7 +1826,7 @@ sub write_gnuplot_file {
 	# set output
 	$gnuplot_input .= "set output\n";
     } elsif ($target eq 'tex') {
-	$gnuplot_input .= "set term postscript eps enhanced $Apache::lonplot::plot{'plotcolor'} solid ";
+	$gnuplot_input .= "set term postscript eps enhanced $Apache::lonplot::plot{'plotcolor'} dash ";
 	if (!$font_properties->{'tex_no_file'}) {
 	    $gnuplot_input .=
 		'fontfile "'.$Apache::lonnet::perlvar{'lonFontsDir'}.
@@ -1585,11 +1834,12 @@ sub write_gnuplot_file {
 	}
 	$gnuplot_input .= ' "'.$font_properties->{'printname'}.'" ';
 	$gnuplot_input .= $fontsize;
-	$gnuplot_input .= "\nset output \"/home/httpd/perl/tmp/".
+	$gnuplot_input .= "\nset output \"".$tmpdir.
 	    &unescape($filename).".eps\"\n";
 	$gnuplot_input .= "set encoding iso_8859_1\n"; # Get access to extended font.
 
     }
+    $gnuplot_input .= "set encoding utf8\n";
     # cartesian or polar plot?
     if (lc($Apache::lonplot::plot{'plottype'}) eq 'polar') {
         $gnuplot_input .= 'set polar'.$/;
@@ -1657,8 +1907,8 @@ sub write_gnuplot_file {
     $gnuplot_input .= "set samples $Apache::lonplot::plot{'samples'}\n";
     # title, xlabel, ylabel
     # titles
-    my $extra_space_x = ($xtics{'location'} eq 'axis') ? ' 0, -0.5 ' : '';
-    my $extra_space_y = ($ytics{'location'} eq 'axis') ? ' -0.5, 0 ' : '';
+    my $extra_space_x = ($xtics{'location'} eq 'axis') ? ' offset 0, -0.5 ' : '';
+    my $extra_space_y = ($ytics{'location'} eq 'axis') ? ' offset -0.5, 0 ' : '';
 
     if ($target eq 'tex') {
 	$gnuplot_input .= "set title  \"$title\"          font \"".$font_properties->{'printname'}.",".$fontsize."pt\"\n" if (defined($title)) ;
@@ -1670,26 +1920,10 @@ sub write_gnuplot_file {
         $gnuplot_input .= "set ylabel \"$ylabel\" $extra_space_y \n" if (defined($ylabel));
     }
     # tics
-    if (%xtics) {    
-	$gnuplot_input .= "set xtics $xtics{'location'} ";
-	$gnuplot_input .= ( $xtics{'mirror'} eq 'on'?"mirror ":"nomirror ");
-	$gnuplot_input .= "$xtics{'start'}, ";
-	$gnuplot_input .= "$xtics{'increment'}, ";
-	$gnuplot_input .= "$xtics{'end'}\n";
-        if ($xtics{'minorfreq'} != 0) {
-            $gnuplot_input .= "set mxtics ".$xtics{'minorfreq'}."\n";
-        } 
-    }
-    if (%ytics) {    
-	$gnuplot_input .= "set ytics $ytics{'location'} ";
-	$gnuplot_input .= ( $ytics{'mirror'} eq 'on'?"mirror ":"nomirror ");
-	$gnuplot_input .= "$ytics{'start'}, ";
-	$gnuplot_input .= "$ytics{'increment'}, ";
-        $gnuplot_input .= "$ytics{'end'}\n";
-        if ($ytics{'minorfreq'} != 0) {
-            $gnuplot_input .= "set mytics ".$ytics{'minorfreq'}."\n";
-        } 
-    }
+    $gnuplot_input .= &generate_tics('xtics', \%xtics, $target);
+
+    $gnuplot_input .= &generate_tics('ytics', \%ytics, $target);
+
     # axis
     if (%axis) {
         if ($axis{'xformat'} ne 'on') {
@@ -1710,6 +1944,26 @@ sub write_gnuplot_file {
         }
 	$gnuplot_input .= "set xrange \[$axis{'xmin'}:$axis{'xmax'}\]\n";
 	$gnuplot_input .= "set yrange \[$axis{'ymin'}:$axis{'ymax'}\]\n";
+		if ($axis{'xzero'} ne 'off') {
+			$gnuplot_input .= "set xzeroaxis ";
+			if ($axis{'xzero'} eq 'line' || $axis{'xzero'} eq 'thick-line') {
+				$gnuplot_input .= "lt -1 ";
+				if ($axis{'xzero'} eq 'thick-line') {
+					$gnuplot_input .= "lw 3 ";
+				}
+			}
+			$gnuplot_input .= "\n";
+		}
+		if ($axis{'yzero'} ne 'off') {
+			$gnuplot_input .= "set yzeroaxis ";
+			if ($axis{'yzero'} eq 'line' || $axis{'yzero'} eq 'thick-line') {
+				$gnuplot_input .= "lt -1 ";
+				if ($axis{'yzero'} eq 'thick-line') {
+					$gnuplot_input .= "lw 3 ";
+				}
+			}
+			$gnuplot_input .= "\n";
+		}
     }
     # Key
     if (%key) {
@@ -1732,7 +1986,10 @@ sub write_gnuplot_file {
         $gnuplot_input .= ' '.$label->{'justify'};
 
         if ($target eq 'tex') {
-	    $gnuplot_input .=' font "'.$font_properties->{'printname'}.','.$fontsize.'pt"' ;
+	    $gnuplot_input .=' font "'.$font_properties->{'printname'}.','.$fontsize.'pt"';
+        }
+        if (($label->{'zlayer'} eq 'front') || ($label->{'zlayer'} eq 'back')) {
+            $gnuplot_input .= ' '.$label->{'zlayer'};
         }
         $gnuplot_input .= $/;
     }
@@ -1741,40 +1998,37 @@ sub write_gnuplot_file {
         $gnuplot_input .="\n";
     }
     # curves
-    $gnuplot_input .= 'plot ';
+    #
+    # Each curve will have its very own linestyle.
+    # (This should work just fine in web rendition I think).
+    #  The line_xxx variables will hold the elements of the line style.
+    #  type (solid/dashed), color, width
+    #
+    my $linestyle_index = 50;
+    my $line_width   = '';
+    my $plots = '';
+
+    # If arrows are needed there will be an arrow style for each as well:
+    #
+
+    my $arrow_style_index = 50;
+
     for (my $i = 0;$i<=$#curves;$i++) {
 	$curve = $curves[$i];
-	$gnuplot_input.= ', ' if ($i > 0);
+	my $plot_command = '';
+	my $plot_type = '';
+	if ($i > 0) {
+	    $plot_type = ', ';
+	}
 	if ($target eq 'tex') {
 	    $curve->{'linewidth'} *= 2;
 	}
+	$line_width = $curve->{'linewidth'};
 	if (exists($curve->{'function'})) {
-	    $gnuplot_input.= 
+	    $plot_type  .= 
 		$curve->{'function'}.' title "'.
 		$curve->{'name'}.'" with '.
                 $curve->{'linestyle'};
-
-            if (($curve->{'linestyle'} eq 'points')      ||
-                ($curve->{'linestyle'} eq 'linespoints') ||
-                ($curve->{'linestyle'} eq 'errorbars')   ||
-                ($curve->{'linestyle'} eq 'xerrorbars')  ||
-                ($curve->{'linestyle'} eq 'yerrorbars')  ||
-                ($curve->{'linestyle'} eq 'xyerrorbars')) {
-                $gnuplot_input.=' pointtype '.$curve->{'pointtype'};
-                $gnuplot_input.=' pointsize '.$curve->{'pointsize'};
-            } elsif ($curve->{'linestyle'} eq 'filledcurves') { 
-                $gnuplot_input.= ' '.$curve->{'limit'};
-            } elsif ($curve->{'linetype'} ne '' &&
-                     $curve->{'linestyle'} eq 'lines') {
-                $gnuplot_input.= ' linetype ';
-                $gnuplot_input.= $linetypes{$curve->{'linetype'}};
-                $gnuplot_input.= ' linecolor rgb "';
-                # convert color from xaaaaaa to #aaaaaa
-                $curve->{'color'} =~ s/^x/#/;
-                $gnuplot_input.= $curve->{'color'}.'"';
-            }
-            $gnuplot_input.= ' linewidth '.$curve->{'linewidth'};
-
 	} elsif (exists($curve->{'data'})) {
 	    # Store data values in $datatext
 	    my $datatext = '';
@@ -1795,34 +2049,77 @@ sub write_gnuplot_file {
 	    print $fh $datatext;
 	    close($fh);
 	    #   generate gnuplot text
-	    $gnuplot_input.= '"'.$datafilename.'" title "'.
+	    $plot_type .= '"'.$datafilename.'" title "'.
 		$curve->{'name'}.'" with '.
 		$curve->{'linestyle'};
-            if (($curve->{'linestyle'} eq 'points')      ||
-                ($curve->{'linestyle'} eq 'linespoints') ||
-                ($curve->{'linestyle'} eq 'errorbars')   ||
-                ($curve->{'linestyle'} eq 'xerrorbars')  ||
-                ($curve->{'linestyle'} eq 'yerrorbars')  ||
-                ($curve->{'linestyle'} eq 'xyerrorbars')) {
-                $gnuplot_input.=' pointtype '.$curve->{'pointtype'};
-                $gnuplot_input.=' pointsize '.$curve->{'pointsize'};
-            } elsif ($curve->{'linestyle'} eq 'filledcurves') { 
-                $gnuplot_input.= ' '.$curve->{'limit'};
-            } elsif ($curve->{'linetype'} ne '' &&
-                     $curve->{'linestyle'} eq 'lines') {
-                $gnuplot_input.= ' linetype ';
-                $gnuplot_input.= $linetypes{$curve->{'linetype'}};
-                $gnuplot_input.= ' linecolor rgb "';
-                # convert color from xaaaaaa to #aaaaaa
-                $curve->{'color'} =~ s/^x/#/;
-                $gnuplot_input.= $curve->{'color'}.'"';
-            }
-                $gnuplot_input.= ' linewidth '.$curve->{'linewidth'}; 
 	}
+	my $pointtype = '';
+	my $pointsize = '';
+
+	# Figure out the linestyle:
+
+	my $lt = $curve->{'linetype'} ne '' ? $curve->{'linetype'} 
+	                : 'solid';	# Line type defaults to solid.
+	# The mapping of lt -> the actual gnuplot line type depends on the target:
+
+	if ($target eq 'tex') {
+	    $lt = $ps_linetypes{$lt};
+	} else {
+	    $lt = $linetypes{$lt}
+	}
+
+	my $color = $curve->{'color'};
+	$color =~ s/^x/#/;	        # Convert xhex color -> #hex color.   
+
+
+	if (($curve->{'linestyle'} eq 'points')      ||
+	    ($curve->{'linestyle'} eq 'linespoints') ||
+	    ($curve->{'linestyle'} eq 'errorbars')   ||
+	    ($curve->{'linestyle'} eq 'xerrorbars')  ||
+	    ($curve->{'linestyle'} eq 'yerrorbars')  ||
+	    ($curve->{'linestyle'} eq 'xyerrorbars')) {
+	    
+	    $pointtype =' pointtype '.$curve->{'pointtype'};
+	    $pointsize =' pointsize '.$curve->{'pointsize'};
+	} elsif ($curve->{'linestyle'} eq 'filledcurves') { 
+	    $plot_command.= ' '.$curve->{'limit'};
+	} elsif ($curve->{'linestyle'} eq 'vector') {
+
+	    # Create the arrow head style add it to 
+	    # $gnuplot_input..and ensure it gets
+	    # Selected in the plot command.
+
+	    $gnuplot_input .= "set style arrow $arrow_style_index ";
+	    $gnuplot_input .= ' ' . $curve->{'arrowhead'};
+	    $gnuplot_input .= ' size ' . $curve->{'arrowlength'};
+	    $gnuplot_input .= ','.$curve->{'arrowangle'};
+	    $gnuplot_input .= ',' . $curve->{'arrowbackangle'}; 
+	    $gnuplot_input .=  ' ' . $curve->{'arrowstyle'} . " ls $linestyle_index\n";
+
+
+	    $plot_command  .= "  arrowstyle $arrow_style_index ";
+	    $arrow_style_index++;
+	}
+
+        my $style_command = "set style line $linestyle_index $pointtype $pointsize linetype $lt linewidth $line_width lc rgb '$color'\n";
+        $gnuplot_input .= $style_command;
+
+	# The condition below is because gnuplot lumps the linestyle in with the 
+	# arrowstyle _sigh_.
+
+	if ($curve->{'linestyle'} ne 'vector') {
+	    $plot_command.= " ls $linestyle_index";
+	}
+
+	$plots .= $plot_type . ' ' . $plot_command;
+	$linestyle_index++;	# Each curve get a unique linestyle.
     }
+    $gnuplot_input .= 'plot '.$plots;
     # Write the output to a file.
-    open (my $fh,">$tmpdir$filename.data");
-    binmode($fh, ":utf8");
+
+    # &Apache::lonnet::logthis($gnuplot_input); # uncomment to log the gnuplot input.
+    open (my $fh, "> $tmpdir$filename.data");
+    binmode($fh, ':utf8');
     print $fh $gnuplot_input;
     close($fh);
     # That's all folks.
@@ -1869,7 +2166,8 @@ sub edit_attributes {
 	if ($defaults->{$attr}->{'edit_type'} eq 'entry') {
 	    $result .= &Apache::edit::text_arg
 		($description,$attr,$token,
-		 $defaults->{$attr}->{'size'});
+		 $defaults->{$attr}->{'size'},
+		$defaults->{$attr}->{'class'});
 	} elsif ($defaults->{$attr}->{'edit_type'} eq 'choice') {
 	    $result .= &Apache::edit::select_or_text_arg
 		($description,$attr,$defaults->{$attr}->{'choices'},$token);
@@ -1998,3 +2296,118 @@ sub insert_data {
 __END__
 
 
+=head1 NAME
+
+Apache::lonplot.pm
+
+=head1 SYNOPSIS
+
+XML-based plotter of graphs
+
+This is part of the LearningOnline Network with CAPA project
+described at http://www.lon-capa.org.
+
+
+=head1 SUBROUTINES (parsing and edit rendering)
+
+=over
+
+=item start_gnuplot()
+
+=item end_gnuplot()
+
+=item start_xtics()
+
+=item end_xtics()
+
+=item start_ytics()
+
+=item end_ytics()
+
+=item get_font()
+
+=item start_key()
+
+=item end_key()
+
+=item parse_label()
+
+=item replace_entities()
+
+=item start_title()
+
+=item end_title()
+
+=item start_xlabel()
+
+=item end_xlabel()
+
+=item start_ylabel()
+
+=item end_label()
+
+=item start_curve()
+
+=item end_curve()
+
+=item start_function()
+
+=item end_function()
+
+=item start_data()
+
+=item end_data()
+
+=item start_axis()
+
+=item end_axis
+
+=back
+
+=head1 SUBROUTINES (Utility)
+
+=over
+
+=item set_defaults()
+
+=item get_attributes()
+
+=item write_gnuplot_file()
+
+=item check_inputs()
+
+=item edit_attributes()
+
+=back
+
+=head1 SUBROUTINES (Insertion functions for editing plots)
+
+=over
+
+=item insert_gnuplot()
+
+=item insert_tics()
+
+=item insert_xtics()
+
+=item insert_key()
+
+=item insert_axis()
+
+=item insert_title()
+
+=item insert_xlabel()
+
+=item insert_ylabel()
+
+=item insert_label()
+
+=item insert_curve()
+
+=item insert_function()
+
+=item insert_data()
+
+=back
+
+=cut