commit 7c7186a05bdb09f1aff854f08d35b2022951046f
Author: Pedro Lozano <peterlozano@gmail.com>
Date:   Tue Apr 19 00:50:55 2011 +0200

    Allow other modules to extend chart parameters.

diff --git chart.module chart.module
index 1040248..731d66b 100644
--- chart.module
+++ chart.module
@@ -316,6 +316,12 @@ function chart_build($chart) {
   _chart_append('chld',  $chart['#countries'],               $data);
   _chart_append('chtm',  $chart['#georange'],                $data);
 
+  // Chart after_build hook
+  foreach (module_implements('chart_after_build') as $module) {
+    $function = $module . '_chart_after_build';
+    $function($chart['#chart_id'], $chart, $data);
+  }
+
   $charts[$chart['#chart_id']] = drupal_query_string_encode($data);
 
   return $charts[$chart['#chart_id']];