Define custom markers per marker type with Geofield Map

I like this approach! In my case I needed to check which view I was currently altering, and I also needed some data from the rendered row result in order to use custom numbered markers. Here's what I changed:

-          $context = array('view_row' => $result);
+          $context = array(
+            'view_name' => $this->view->name,
+            'view_display' => $this->view->current_display,
+            'view_row' => $result,
+            'view_row_rendered' => $this->rendered_fields[$id],
+          );

Here's how I am using the new context info. (My view is configured in Views UI with a result counter, which is available in view_row_rendered but not in view_row.)

function mymodule_geofield_map_data_alter($datum, $context) {
  if (!empty($context['view_row']) && $context['view_name'] == 'my_map') {
    $path = '/' . drupal_get_path('module', 'mymodule') . '/markers/';

    // Path to custom numbered marker icon, e.g. mymodule/markers/number12.png .
    $result_counter = $context['view_row_rendered']['counter'];
    $icon = $path . 'number' . $result_counter . '.png';

    // Set path to custom icon.
    $datum->options['icon'] = $icon;
  }
}