%
% bars.tex
%
\section{Chart::Bars}
\index{Chart::Bars}
\name{Chart::Bars}
\file{Bars.pm}
\requires{Chart::Base, GD, Carp, FileHandle}
\begin{Description} 
   \class{Bars} is a \textbf{subclass} of the module \module{Chart::Base}.
   The class \class{Bars} creates a chart with bars.
\end{Description}

\parindent 0pt{\large Example:}
\begin{figure}[h]
 	\begin{center}
		\includegraphics[scale=0.4]{d_bars.png}
	\end{center}
	\caption{Bars chart}
	\label{fig:bars}
\end{figure}

\begin{verbatim}
use Chart::Bars;

$g = Chart::Bars->new(600,500);

$g->add_dataset ('Berlin', 'Paris', 'Rome', 'London', 'Munich');
$g->add_dataset (14, 5, 4, 5, 11);
$g->add_dataset (12, 4, 6, 7, 12);
$g->add_dataset (18, 2, 3, 3, 9);
$g->add_dataset (17, 5, 7, 6, 6);
$g->add_dataset (15, 3, 4, 5, 11);
$g->add_dataset (11, 6, 5, 6, 12);
$g->add_dataset (12, 1, 4, 5, 15);
$g->add_dataset (10, 4, 6, 8, 10);
$g->add_dataset (14, 5, 4, 5, 11);
$g->add_dataset (12, 4, 6, 6, 12);
$g->add_dataset (18, 2, 3, 3, 9);
$g->add_dataset (17, 5, 7, 2, 6);

%hash = ('title' => 'Sold Cars in 2001',
         'text_space' => 5,
         'grey_background' => 'false',
         'integer_ticks_only' => 'true',
         'x_label' => 'City',
         'y_label' => 'Number of Cars',
         'legend' => 'bottom',
         'legend_labels' => ['January' , 'February' , 'March', 'April',
                             'May', 'June', 'July', 'August', 'September',
                             'October', 'November', 'December'],
         'min_val' => 0,
         'max_val' => 20,
         'grid_lines' =>'true',
         'colors' => {'title' => 'red',
                      'x_label' => 'blue',
                      'y_label' => 'blue'} );

$g->set (%hash);

$g->png ("bars.png");

\end{verbatim}

\begin{Constructor} 
An instance of a bars chart object can be created with the constructor new():
\begin{quote}
\parindent 0pt
\fett{\$obj = Chart::Bars->new();}\\
\fett{\$obj = Chart::Bars->new(\kursiv{width}, \kursiv{height});}\\
\end{quote}

If \textit{new()} has no arguments, 
the constructor returns an image with the size 300x400 pixels. 
If new has two arguments \parameter{width} and \parameter{height}, 
it returns an image with the desired size.
\end{Constructor}

\Methods
\method{All universally valid methods, see page \pageref{methods} of 
class \class{Chart::Base}.}\\[\parabstand]
%
\Attributes
All universal valid options, see page \pageref{options}. \\
In addition, the following options for this class are defined:
\begin{description}
\item['y\_axes'] Tell chart where to place the y-axis. 
                 Valid values are 'left', 'right' and 'both'. Defaults to 'left'.
                 
\item['spaced\_bars'] Leaves space between the groups of bars at each data point when set to 'true'.  
             This just makes it easier to read a bar chart.  Default is 'true'.
\end{description}