SVG::TT::Graph::Bar - Create presentation quality SVG bar graphs easily

  use SVG::TT::Graph::Bar;

  my @fields = qw(Jan Feb Mar);
  my @data_sales_02 = qw(12 45 21);

  my $graph = SVG::TT::Graph::Bar->new({
        'height' => '500',
        'width' => '300',
        'fields' => \@fields,
  });

  $graph->add_data({
        'data' => \@data_sales_02,
        'title' => 'Sales 2002',
  });

  print "Content-type: image/svg+xml\r\n\r\n";
  print $graph->burn();

This object aims to allow you to easily create high quality SVG bar graphs. You can either use the default style sheet or supply your own. Either way there are many options which can be configured to give you control over how the graph is generated - with or without a key, data elements at each point, title, subtitle etc.

  use SVG::TT::Graph::Bar;

  # Field names along the X axis
  my @fields = qw(Jan Feb Mar);

  my $graph = SVG::TT::Graph::Bar->new({
    # Required
    'fields' => \@fields,

    # Optional - defaults shown
    'height'            => '500',
    'width'             => '300',
    'show_data_values'  => 1,

    'min_scale_value'           => '0',
        'stagger_x_labels'  => 0,
    'rotate_x_labels'   => 0,
        'bar_gap'           => 1,

    'show_x_labels'     => 1,
    'show_y_labels'     => 1,
    'scale_integers'    => 0,
        'scale_divisions'   => '',

    'show_x_title'      => 0,
    'x_title'           => 'X Field names',

    'show_y_title'      => 0,
    'y_title_text_direction' => 'bt',
    'y_title'           => 'Y Scale',

    'show_graph_title'          => 0,
    'graph_title'           => 'Graph Title',
    'show_graph_subtitle'   => 0,
    'graph_subtitle'        => 'Graph Sub Title',

    'key'                   => 0,
    'key_position'          => 'right',

    # Optional - defaults to using internal stylesheet
    'style_sheet'       => '/includes/graph.css',
  });

The constructor takes a hash reference, fields (the names for each field on the X axis) MUST be set, all other values are defaulted to those shown above - with the exception of style_sheet which defaults to using the internal style sheet.

  my @data_sales_02 = qw(12 45 21);

  $graph->add_data({
    'data' => \@data_sales_02,
    'title' => 'Sales 2002',
  });

This method allows you to add data to the graph object. It can be called several times to add more data sets in, but the likely hood is you should be using SVG::TT::Graph::Line as it won't look great!

  my $graph->clear_data();

This method removes all data from the object so that you can reuse it to create a new graph but with the same config options.

  print $graph->burn();

This method processes the template with the data and config which has been set and returns the resulting SVG.

This method will croak unless at least one data set has been added to the graph object.

  my $value = $graph->method();
  my $confirmed_new_value = $graph->method($value);

The following is a list of the methods which are available to change the config of the graph object after it has been created.

height()

Set the height of the graph box, this is the total height of the SVG box created - not the graph it self which auto scales to fix the space.

width()

Set the width of the graph box, this is the total width of the SVG box created - not the graph it self which auto scales to fix the space.

style_sheet()

Set the path to an external stylesheet, set to '' if you want to revert back to using the defaut internal version. To create an external stylesheet create a graph using the default internal version and copy the stylesheet section to an external file and edit from there.

show_data_values()

Show the value of each element of data on the graph

bar_gap()

Whether to have a gap between the bars or not, default is '1', set to '0' if you don't want gaps.

min_scale_value()

The point at which the Y axis starts, defaults to '0', if set to '' it will default to the minimum data value.

show_x_labels()

Whether to show labels on the X axis or not, defaults to 1, set to '0' if you want to turn them off.

stagger_x_labels()

This puts the labels at alternative levels so if they are long field names they will not overlap so easily. Default it '0', to turn on set to '1'.

rotate_x_labels()

This turns the X axis labels by 90 degrees. Default it '0', to turn on set to '1'.

show_y_labels()

Whether to show labels on the Y axis or not, defaults to 1, set to '0' if you want to turn them off.

scale_integers()

Ensures only whole numbers are used as the scale divisions. Default it '0', to turn on set to '1'. This has no effect if scale divisions are less than 1.

scale_divisions()

This defines the gap between markers on the Y axis, default is a 10th of the max_value, e.g. you will have 10 markers on the Y axis. NOTE: do not set this too low - you are limited to 999 markers, after that the graph won't generate.

show_x_title()

Whether to show the title under the X axis labels, default is 0, set to '1' to show.

x_title()

What the title under X axis should be, e.g. 'Months'.

show_y_title()

Whether to show the title under the Y axis labels, default is 0, set to '1' to show.

y_title_text_direction()

Aligns writing mode for Y axis label. Defaults to 'bt' (Bottom to Top). Change to 'tb' (Top to Bottom) to reverse.

y_title()

What the title under Y axis should be, e.g. 'Sales in thousands'.

show_graph_title()

Whether to show a title on the graph, defaults to 0, set to '1' to show.

graph_title()

What the title on the graph should be.

show_graph_subtitle()

Whether to show a subtitle on the graph, defaults to 0, set to '1' to show.

graph_subtitle()

What the subtitle on the graph should be.

key()

Whether to show a key, defaults to 0, set to '1' if you want to show it.

key_position()

Where the key should be positioned, defaults to 'right', set to 'bottom' if you want to move it.

The default stylesheet handles upto 12 data sets, if you use more you must create your own stylesheet and add the additional settings for the extra data sets. You will know if you go over 12 data sets as they will have no style and be in black.

For examples look at the project home page http://leo.cuckoo.org/projects/SVG-TT-Graph/

None by default.

Stephen Morgan for creating the TT template and SVG.

Leo Lapworth (LLAP@cuckoo.org)

SVG::TT::Graph, SVG::TT::Graph::Line, SVG::TT::Graph::BarHorizontal, SVG::TT::Graph::BarLine, SVG::TT::Graph::Pie, SVG::TT::Graph::TimeSeries