Draw a Simple Pie Chart

1. Load the API into the page you would like your diagram using <php tripald3_load_libraries();?>
2. Retrieve you data and manipulate it into the structure required by the chart. This can be done a number of ways, the easiest of which is to query your database in your Drupal preprocess hook and then save the results as a javascript setting.

/**
 * Preprocess hook for template my_example.tpl.php
 * The module name is demo.
 */
function demo_my_example_preprocess(&$variables) {

  // Load the API (Step #1 above)
  tripald3_load_libraries();

  // Retrieve your data.
  // For this example  we're just going to define the array directly.
  $data  = [
    [
      "label": "Accession",
      "count": 2390,
    ],
    [
      "label": "Breeders Cross",
      "count": 567,
    ],
    [
      "label": "Recombinant Inbred Line",
      "count": 115,
    ],
    [
      "label": "Cultivated Variety",
      "count": 78,
    ],
  ];

  // Make it available to javascript via settings.
  $settings = array(
    // Always namespace to your module to avoid collisions.
    'demo' => array(
      // Pass in your data using a descriptive settings key.
      'stockTypePieData' => $data,
    ),
  );
  drupal_add_js($settings, 'setting');
}

3. Add a container element in your template where you would like the chart drawn.

<div id="tripald3-simplepie" class="tripald3-diagram">
  <!-- Javascript will add the Simple Pie Chart, Title and Figure legend here -->
</div>

4. Draw the chart in your template by calling tripalD3.drawChart(). This is done within a script tag using Drupal behaviours to ensure it is run at the correct point and the data prepared is passed in.

<script type="text/javascript">
  Drupal.behaviors.tripalD3demoSimplePie = {
    attach: function (context, settings) {

      // Pull the data out of the javascript settings.
      var data = Drupal.settings.demo.stockTypePieData;

      // Draw your chart.
      tripalD3.drawFigure(
        data,
        {
          "chartType" : "simplepie",
          "elementId": "tripald3-simplepie",
          "height": 250,
          "width": 500,
          "keyPosition": "right",
          "title": "Proportion of <em>Tripalus databasica</em> Germplasm Types",
          "legend": "The above pie chart depicts the ratio of germplasm types available for <em>Tripalus databasica</em>.",
        }
      );
    }
  };
</script>

5. There is no step #5; you’re done!