fb.process.inc in Drupal for Facebook 7.3

Helper functions for processing links.

Both canvas pages and tab pages need to alter links, changing both URLs and attributes such as target. This cannot always be done via Drupal's url rewriting.

File

fb.process.inc

<?php

/**
 * @file
 * Helper functions for processing links.
 *
 * Both canvas pages and tab pages need to alter links, changing both URLs and
 * attributes such as target.  This cannot always be done via Drupal's url
 * rewriting.
 */

/**
 * This function uses regular expressions to convert links on canvas pages
 * to URLs that begin http://apps.facebook.com/...
 *
 * This is a relatively expensive operation.  In the past, this had to be run
 * on all FBML canvas pages.  Now with iframe canvas pages, this is not
 * strictly needed, but remains useful.  If processed, links on the page will
 * change the parent frame (the one with the URL shown in the browser).  If
 * not processed, the links will change only the iframe.
 *
 *
 * @param $output is the page (or iframe block) about to be returned.
 *
 * @param $options - 'add_target' will cause target=_top to be added
 * when producing an iframe. 'absolute_links' will change hrefs with absolute
 * URLs to refer to canvas pages.
 *
 */
function fb_process($output, $options = array()) {
  global $base_url;
  global $_fb, $_fb_app;

  // Default to canvas links.
  if (!isset($options['to_canvas'])) {
    $options['to_canvas'] = $_fb_app->canvas;
  }
  $patterns = array();
  $replacements = array();
  $base_path = base_path();
  $targets_added = FALSE;
  if ($_fb) {
    if (function_exists('fb_url_outbound_alter')) {
      $rewrite_options = array(
        FB_SETTINGS_CB_SESSION => FALSE,
        FB_SETTINGS_CB_TYPE => FALSE,
      );
      $base_rewrite = '';
      fb_url_outbound_alter($base_rewrite, $rewrite_options, '');
      $base = $base_path . $base_rewrite;

      // short URL with rewrite applied.
    }
    else {

      // If no url_alter, use normal base_path.
      $base = $base_path;
    }
    $protocol = fb_protocol();

    // http or https
    if (!isset($options['relative_links']) || $options['relative_links']) {
      if (isset($options['to_canvas']) && ($canvas = $options['to_canvas'])) {

        // Make relative links point to canvas pages.
        $patterns[] = "|<a([^>]*)href=\"{$base}|";
        $replacements[] = "<a \$1 href=\"{$protocol}://apps.facebook.com/{$canvas}/";
      }
      elseif (!empty($options['to_page'])) {

        // Make relative links point to page tab.
        $to_page = $options['to_page'];

        // Note that url parameters will be lost on page tabs.  Facebook will not pass them on to our iframe.
        $patterns[] = "|<a([^>]*)href=\"{$base}([^\"\\?]*)\\?|";
        $replacements[] = "<a \$1 href=\"{$to_page}" . "&app_data=\$2&";

        // Pattern without URL params.
        $patterns[] = "|<a([^>]*)href=\"{$base}|";
        $replacements[] = "<a \$1 href=\"{$to_page}" . "&app_data=";
      }
      else {

        // Make relative links point to website.
        $site_base = url('<front>', array(
          'absolute' => TRUE,
          'fb_url_alter' => FALSE,
        ));
        $patterns[] = "|<a([^>]*)href=\"{$base}|";
        $replacements[] = "<a \$1 href=\"{$site_base}";
      }

      // Add target=_top so that entire pages do not appear within an iframe.
      // TODO: make these pattern replacements more sophisticated, detect whether target is already set.
      if (isset($options['add_target']) && ($target = $options['add_target'])) {

        // Add target=_top to all links
        $patterns[] = "|<a ([^>]*)href=\"|";
        $replacements[] = "<a \$1 target=\"{$target}\" href=\"";

        // Do not change local forms, but do change external ones
        $patterns[] = "|<form([^>]*)action=\"([^:\"]*):|";
        $replacements[] = "<form target=\"{$target}\" \$1 action=\"\$2:";
        $targets_added = TRUE;
      }
    }
    if (!$targets_added) {

      // Add target=_top to only external links
      $patterns[] = "|<a([^>]*)href=\"([^:\"]*):|";
      $replacements[] = "<a target=\"_top\" \$1 href=\"\$2:";
      $patterns[] = "|<form([^>]*)action=\"([^:\"]*):|";
      $replacements[] = "<form target=\"_top\" \$1 action=\"\$2:";
    }
    if (isset($options['absolute_links']) && $options['absolute_links']) {

      // Make absolute links point to canvas pages.
      $absolute_base = url('<front>', array(
        'absolute' => TRUE,
      ));
      $patterns[] = "|<a([^>]*)href=\"{$absolute_base}|";
      $replacements[] = "<a \$1 href=\"{$protocol}://apps.facebook.com/{$_fb_app->canvas}/";
    }
  }
  if (count($patterns)) {
    $count = 0;
    $return = preg_replace($patterns, $replacements, $output, -1, $count);

    //print ("fb_process replaced $count.\n\n"); // debug
    return $return;
  }
  else {
    return $output;
  }
}

Functions

Name	Description
fb_process	This function uses regular expressions to convert links on canvas pages to URLs that begin http://apps.facebook.com/...