pagepreview.module in Page Preview 6

An alternative node previewing system for the node add/edit form.

File

pagepreview.module

<?php

/**
 * @file
 * An alternative node previewing system for the node add/edit form.
 */

/**
 * Implements hook_menu().
 */
function pagepreview_menu() {
  $items = array();
  $items['pagepreview/%'] = array(
    'title' => 'Page Preview',
    'description' => 'Menu callback for rendering a full-page preview.',
    'page callback' => 'pagepreview_get_preview',
    'page arguments' => array(
      1,
    ),
    'access arguments' => array(
      'access content',
    ),
    'type' => MENU_CALLBACK,
  );
  return $items;
}

/**
 * Implements hook_form_alter().
 *
 * Replaces the default submit callback for the "Preview" button.
 */
function pagepreview_form_alter(&$form, &$form_state, $form_id) {
  if ($form['#id'] == 'node-form') {
    if ($form['buttons']['preview']) {
      $form['buttons']['preview']['#submit'] = array(
        'pagepreview_node_form_build_preview',
      );
    }
  }
}

/**
 * Alternate submit callback for the node form "Preview" button.
 */
function pagepreview_node_form_build_preview($form, &$form_state) {
  $node = node_form_submit_build_node($form, $form_state);
  $node->pagepreview = TRUE;

  // Get the expected URL alias from Pathauto, if applicable.
  if (module_exists('pathauto') && (!isset($node->pathauto_perform_alias) || $node->pathauto_perform_alias)) {
    _pathauto_include();
    $placeholders = pathauto_get_placeholders('node', $node);
    $src = "node/" . $node->nid;
    $alias = pathauto_create_alias('node', 'return', $placeholders, $src, $node->nid, $node->type, $node->language);
    if ($alias) {
      $node->path = $alias;
    }
  }

  // Cache the temporary node and active the preview area of the node form.
  cache_set('pagepreview:' . $form['form_token']['#default_value'], $node, 'cache_page', CACHE_TEMPORARY);
  $form_state['node_preview'] = '<iframe class="pagepreview-preview" style="width:100%; height: 480px;" src="' . base_path() . 'pagepreview/' . $form['#token'] . '"></iframe>';
  drupal_set_title(t('Preview'));
}

/**
 * Implements hook_init().
 *
 * We need drupal_is_front_page() to reflect the page being previewed, not the
 * path of the pagepreview callback. Since the result of drupal_is_front_page()
 * is statically cached, we have to call it first and trick it.
 */
function pagepreview_init() {

  // We only want to do this on pagepreview requests.
  $path = $_GET['q'];
  $parts = explode('/', $path);
  if ($parts[0] == 'pagepreview' && isset($parts[1])) {

    // Get the cached temporary node.
    $form_token = drupal_get_token($parts[1]);
    $cache = cache_get('pagepreview:' . $form_token, 'cache_page');

    // If we can't find a cached node, might as well quit here.
    if (!$cache) {
      print t('There was a problem generating the preview. Please review the form for error and try again.');
      exit;
    }

    // Switch $_GET['q'] to the expected path, call drupal_is_front_page() to
    // set the static cache, the switch $_GET['q'] back to the original.
    $node = $cache->data;
    if ($node->nid) {
      $_GET['q'] = 'node/' . $node->nid;
    }
    drupal_is_front_page();
    $_GET['q'] = $path;

    // Meanwhile, don't allow the preview result to be cached.
    $GLOBALS['conf']['cache'] = FALSE;
  }
}

/**
 * Menu callback for "pagepreview/%".
 *
 * Directly prints a rendered page based on the cached temporary node.
 *
 * @param $token
 *   The value of $form['#token']. This is generally the form ID.
 */
function pagepreview_get_preview($token) {

  // Get the cached temporary node.
  $form_token = drupal_get_token($token);
  $cache = cache_get('pagepreview:' . $form_token, 'cache_page');
  $node = $cache->data;
  drupal_set_title($node->title);

  // Overrides $_GET['q'] so that other elements on the page can react to the
  // proper path context.
  if ($node->nid) {
    $_GET['q'] = 'node/' . $node->nid;
  }
  elseif (!empty($node->path)) {
    $_GET['q'] = trim($node->path, '/');
  }
  elseif (!empty($node->old_alias)) {
    $_GET['q'] = trim($node->old_alias, '/');
  }
  $preview = pagepreview_render_preview($node);

  // Switch to the anonymous user for page rendering.
  // TODO: make this configurable.
  global $user;
  $orig_user = $user;
  $user = user_load(0);

  // Suppress fancy stuff like admin and admin_menu.module for the preview.
  module_invoke_all('suppress');
  print theme('page', $preview);
  $user = $orig_user;
}

/**
 * Replacement function for node_preview().
 *
 * Instead of calling theme('node_preview') to get the node output, we call
 * node_view directly.
 *
 * @see theme_node_preview()
 */
function pagepreview_render_preview($node) {
  if (node_access('create', $node) || node_access('update', $node)) {

    // Load the user's name when needed.
    if (isset($node->name)) {

      // The use of isset() is mandatory in the context of user IDs, because
      // user ID 0 denotes the anonymous user.
      if ($user = user_load(array(
        'name' => $node->name,
      ))) {
        $node->uid = $user->uid;
        $node->picture = $user->picture;
      }
      else {
        $node->uid = 0;

        // anonymous user
      }
    }
    elseif ($node->uid) {
      $user = user_load(array(
        'uid' => $node->uid,
      ));
      $node->name = $user->name;
      $node->picture = $user->picture;
    }
    $node->changed = time();

    // Display a preview of the node.
    // Previewing alters $node so it needs to be cloned.
    if (!form_get_errors()) {
      $cloned_node = drupal_clone($node);
      $cloned_node->build_mode = NODE_BUILD_PREVIEW;

      // If enabled, allow page_manager.module to handle node rendering.
      if (module_exists('page_manager')) {
        module_load_include('inc', 'page_manager', 'plugins/tasks/node_view');
        $output = page_manager_node_view($cloned_node);
      }
      else {
        $output = node_view($cloned_node, 0, 1, 1);
      }
    }
    return $output;
  }
}

Functions

Name	Description
pagepreview_form_alter	Implements hook_form_alter().
pagepreview_get_preview	Menu callback for "pagepreview/%".
pagepreview_init	Implements hook_init().
pagepreview_menu	Implements hook_menu().
pagepreview_node_form_build_preview	Alternate submit callback for the node form "Preview" button.
pagepreview_render_preview	Replacement function for node_preview().