diff -r 07239de796bb -r e756a8c72c3d cms/drupal/modules/field_ui/field_ui.api.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cms/drupal/modules/field_ui/field_ui.api.php	Fri Sep 08 12:04:06 2017 +0200
@@ -0,0 +1,207 @@
+<?php
+
+/**
+ * @file
+ * Hooks provided by the Field UI module.
+ */
+
+/**
+ * @addtogroup field_types
+ * @{
+ */
+
+/**
+ * Add settings to a field settings form.
+ *
+ * Invoked from field_ui_field_settings_form() to allow the module defining the
+ * field to add global settings (i.e. settings that do not depend on the bundle
+ * or instance) to the field settings form. If the field already has data, only
+ * include settings that are safe to change.
+ *
+ * @todo: Only the field type module knows which settings will affect the
+ * field's schema, but only the field storage module knows what schema
+ * changes are permitted once a field already has data. Probably we need an
+ * easy way for a field type module to ask whether an update to a new schema
+ * will be allowed without having to build up a fake $prior_field structure
+ * for hook_field_update_forbid().
+ *
+ * @param $field
+ *   The field structure being configured.
+ * @param $instance
+ *   The instance structure being configured.
+ * @param $has_data
+ *   TRUE if the field already has data, FALSE if not.
+ *
+ * @return
+ *   The form definition for the field settings.
+ */
+function hook_field_settings_form($field, $instance, $has_data) {
+  $settings = $field['settings'];
+  $form['max_length'] = array(
+    '#type' => 'textfield',
+    '#title' => t('Maximum length'),
+    '#default_value' => $settings['max_length'],
+    '#required' => FALSE,
+    '#element_validate' => array('element_validate_integer_positive'),
+    '#description' => t('The maximum length of the field in characters. Leave blank for an unlimited size.'),
+  );
+  return $form;
+}
+
+/**
+ * Add settings to an instance field settings form.
+ *
+ * Invoked from field_ui_field_edit_form() to allow the module defining the
+ * field to add settings for a field instance.
+ *
+ * @param $field
+ *   The field structure being configured.
+ * @param $instance
+ *   The instance structure being configured.
+ *
+ * @return
+ *   The form definition for the field instance settings.
+ */
+function hook_field_instance_settings_form($field, $instance) {
+  $settings = $instance['settings'];
+
+  $form['text_processing'] = array(
+    '#type' => 'radios',
+    '#title' => t('Text processing'),
+    '#default_value' => $settings['text_processing'],
+    '#options' => array(
+      t('Plain text'),
+      t('Filtered text (user selects text format)'),
+    ),
+  );
+  if ($field['type'] == 'text_with_summary') {
+    $form['display_summary'] = array(
+      '#type' => 'select',
+      '#title' => t('Display summary'),
+      '#options' => array(
+        t('No'),
+        t('Yes'),
+      ),
+      '#description' => t('Display the summary to allow the user to input a summary value. Hide the summary to automatically fill it with a trimmed portion from the main post.'),
+      '#default_value' => !empty($settings['display_summary']) ? $settings['display_summary'] :  0,
+    );
+  }
+
+  return $form;
+}
+
+/**
+ * Add settings to a widget settings form.
+ *
+ * Invoked from field_ui_field_edit_form() to allow the module defining the
+ * widget to add settings for a widget instance.
+ *
+ * @param $field
+ *   The field structure being configured.
+ * @param $instance
+ *   The instance structure being configured.
+ *
+ * @return
+ *   The form definition for the widget settings.
+ */
+function hook_field_widget_settings_form($field, $instance) {
+  $widget = $instance['widget'];
+  $settings = $widget['settings'];
+
+  if ($widget['type'] == 'text_textfield') {
+    $form['size'] = array(
+      '#type' => 'textfield',
+      '#title' => t('Size of textfield'),
+      '#default_value' => $settings['size'],
+      '#element_validate' => array('element_validate_integer_positive'),
+      '#required' => TRUE,
+    );
+  }
+  else {
+    $form['rows'] = array(
+      '#type' => 'textfield',
+      '#title' => t('Rows'),
+      '#default_value' => $settings['rows'],
+      '#element_validate' => array('element_validate_integer_positive'),
+      '#required' => TRUE,
+    );
+  }
+
+  return $form;
+}
+
+
+/**
+ * Specify the form elements for a formatter's settings.
+ *
+ * This hook is only invoked if hook_field_formatter_settings_summary()
+ * returns a non-empty value.
+ *
+ * @param $field
+ *   The field structure being configured.
+ * @param $instance
+ *   The instance structure being configured.
+ * @param $view_mode
+ *   The view mode being configured.
+ * @param $form
+ *   The (entire) configuration form array, which will usually have no use here.
+ * @param $form_state
+ *   The form state of the (entire) configuration form.
+ *
+ * @return
+ *   The form elements for the formatter settings.
+ */
+function hook_field_formatter_settings_form($field, $instance, $view_mode, $form, &$form_state) {
+  $display = $instance['display'][$view_mode];
+  $settings = $display['settings'];
+
+  $element = array();
+
+  if ($display['type'] == 'text_trimmed' || $display['type'] == 'text_summary_or_trimmed') {
+    $element['trim_length'] = array(
+      '#title' => t('Length'),
+      '#type' => 'textfield',
+      '#size' => 20,
+      '#default_value' => $settings['trim_length'],
+      '#element_validate' => array('element_validate_integer_positive'),
+      '#required' => TRUE,
+    );
+  }
+
+  return $element;
+
+}
+
+/**
+ * Return a short summary for the current formatter settings of an instance.
+ *
+ * If an empty result is returned, the formatter is assumed to have no
+ * configurable settings, and no UI will be provided to display a settings
+ * form.
+ *
+ * @param $field
+ *   The field structure.
+ * @param $instance
+ *   The instance structure.
+ * @param $view_mode
+ *   The view mode for which a settings summary is requested.
+ *
+ * @return
+ *   A string containing a short summary of the formatter settings.
+ */
+function hook_field_formatter_settings_summary($field, $instance, $view_mode) {
+  $display = $instance['display'][$view_mode];
+  $settings = $display['settings'];
+
+  $summary = '';
+
+  if ($display['type'] == 'text_trimmed' || $display['type'] == 'text_summary_or_trimmed') {
+    $summary = t('Length: @chars chars', array('@chars' => $settings['trim_length']));
+  }
+
+  return $summary;
+}
+
+/**
+ * @} End of "addtogroup field_types".
+ */