diff --git a/analytics_dashboard/analytics_dashboard.charts.inc b/analytics_dashboard/analytics_dashboard.charts.inc
index 577b619..c8010f2 100644
--- a/analytics_dashboard/analytics_dashboard.charts.inc
+++ b/analytics_dashboard/analytics_dashboard.charts.inc
@@ -38,7 +38,7 @@ function analytics_dashboard_charts() {
       'header' => $header,
       'rows' => $rows,
       'columns' => $columns,
-      'chartType' => 'LineChart',// LineChart, PieChart, ,ColumnChart, ,AreaChart, Gauge, BarChart, etc....
+      'chartType' => GOOGLE_CHART_TOOLS_DEFAULT_CHART,// LineChart, PieChart, ,ColumnChart, ,AreaChart, Gauge, BarChart, etc....
       'options' => array( // Optionals.
         'curveType' => "function",
         'forceIFrame' => FALSE,  
@@ -81,7 +81,7 @@ function analytics_dashboard_charts() {
       'header' => $header,
       'rows' => $rows,
       'columns' => $columns,
-      'chartType' => 'LineChart',// LineChart, PieChart, ,ColumnChart, ,AreaChart, Gauge, BarChart, etc....
+      'chartType' => GOOGLE_CHART_TOOLS_DEFAULT_CHART,// LineChart, PieChart, ,ColumnChart, ,AreaChart, Gauge, BarChart, etc....
       'options' => array( // Optionals.
         'curveType' => "function",
         'colors' => array('green'),   
@@ -124,7 +124,7 @@ function analytics_dashboard_charts() {
       'header' => $header,
       'rows' => $rows,
       'columns' => $columns,
-      'chartType' => 'LineChart',// LineChart, PieChart, ,ColumnChart, ,AreaChart, Gauge, BarChart, etc....
+      'chartType' => GOOGLE_CHART_TOOLS_DEFAULT_CHART,// LineChart, PieChart, ,ColumnChart, ,AreaChart, Gauge, BarChart, etc....
       'options' => array( // Optionals.
         'curveType' => "function",
         'colors' => array('purple'),   
@@ -167,7 +167,7 @@ function analytics_dashboard_charts() {
       'header' => $header,
       'rows' => $rows,
       'columns' => $columns,
-      'chartType' => 'LineChart',// LineChart, PieChart, ,ColumnChart, ,AreaChart, Gauge, BarChart, etc....
+      'chartType' => GOOGLE_CHART_TOOLS_DEFAULT_CHART,// LineChart, PieChart, ,ColumnChart, ,AreaChart, Gauge, BarChart, etc....
       'options' => array( // Optionals.
         'curveType' => "function",
         'colors' => array('orange'),   
diff --git a/google_chart_tools.module b/google_chart_tools.module
index 3cbe943..64d9475 100644
--- a/google_chart_tools.module
+++ b/google_chart_tools.module
@@ -1,4 +1,6 @@
 <?php
+// define the default charttype used in examples
+define("GOOGLE_CHART_TOOLS_DEFAULT_CHART", "LineChart");
 /**
  * Implements hook_init(). 
  */
@@ -26,3 +28,37 @@ function draw_chart($settings) {
   );
   return $ret;
 }
+
+/**
+ * Return types of charts that google can render.
+ */
+function google_chart_tools_load_types() {
+  $types = array();
+  // invoke hook that defines google chart types
+  $types = module_invoke_all('define_gct_types');
+  drupal_alter('define_gct_chart_types', $types);
+  return $types;
+}
+
+/**
+ * Implements hook_define_gct_type().
+ */
+function google_chart_tools_define_gct_types() {
+  // define default types from API documentation
+  $types = array(
+    'LineChart' => t('Line Chart'),
+    'PieChart' => t('Pie Chart'),
+    'ColumnChart' => t('Column Chart'),
+    'AreaChart' => t('Area Chart'),
+    'Gauge' => t('Gauge'),
+    'BarChart' => t('Bar Chart'),
+  ); 
+  return $types;
+}
+
+/**
+ * Implements hook_define_gct_type().
+ */
+function google_chart_tools_define_gct_types_alter(&$types) {
+  // placeholder to demonstrate hook_alter method
+}
\ No newline at end of file
diff --git a/google_chart_tools_example/google_chart_tools_example.module b/google_chart_tools_example/google_chart_tools_example.module
index 798ec54..d462b70 100644
--- a/google_chart_tools_example/google_chart_tools_example.module
+++ b/google_chart_tools_example/google_chart_tools_example.module
@@ -51,7 +51,7 @@ function google_chart_tools_page() {
     'header' => $header,
     'rows' => $rows,
     'columns' => $columns,
-    'chartType' => 'LineChart',// LineChart, PieChart, ,ColumnChart, ,AreaChart, Gauge, BarChart, etc....
+    'chartType' => GOOGLE_CHART_TOOLS_DEFAULT_CHART,// LineChart, PieChart, ,ColumnChart, ,AreaChart, Gauge, BarChart, etc....
     'containerId' =>  'line_chart',
     'options' => array( // Optionals.
       'curveType' => "function", 
diff --git a/google_chart_tools_views/views/google_chart_tools_views_plugin_style.inc b/google_chart_tools_views/views/google_chart_tools_views_plugin_style.inc
index 26427de..31cbac1 100644
--- a/google_chart_tools_views/views/google_chart_tools_views_plugin_style.inc
+++ b/google_chart_tools_views/views/google_chart_tools_views_plugin_style.inc
@@ -15,7 +15,7 @@ class google_chart_tools_views_plugin_style extends views_plugin_style {
     $options = parent::option_definition();
     
     $options['title'] = array('default' => '');
-    $options['type'] = array('default' => 'LineChart');
+    $options['type'] = array('default' => GOOGLE_CHART_TOOLS_DEFAULT_CHART);
     $options['width'] = array('default' => 600);
     $options['height'] = array('default' => 400);
     $options['curve'] = array('default' => 0);
@@ -37,10 +37,10 @@ class google_chart_tools_views_plugin_style extends views_plugin_style {
       '#default_value' => $this->options['title'],
     );
     $form['type'] = array(
-      '#type' => 'textfield',
+      '#type' => 'select',
+      '#options' => google_chart_tools_load_types(),
       '#title' => t('Type'),
       '#description' => t('Chart type, see <a href="https://google-developers.appspot.com/chart/interactive/docs/gallery">Google Chart Tools gallery</a>.'),
-      '#size' => 16,
       '#required' => TRUE,
       '#description' => t('Ex. LineChart, PieChart, ColumnChart, AreaChart, Gauge, BarChart, etc....'),  
       '#default_value' => $this->options['type'],