Image licence

gistfile1.aw

<?php

/**
 * Image license
 *
 * Used to check for a specific machine tag which allows us to display appropriate
 * image attribution.
 *
 * Usage:
 *   
 *    <?php print imageLicense($imageURL); ?>
 *
 * If this becomes useful, I may abstract it further into a general machine tag
 * parser, but for now I'm stopping myself from over-engineering things. 
 *
 * NOTE:
 *   This requires JaduMultumediaItemTags.tag to be set to varchar(255)
 *   Jadu have made this change for us in the 1.10 trunk, but we'll need to patch any
 *  older instances with the following query.
 *
 *     ALTER TABLE JaduMultimediaItemTags CHANGE tag tag varchar(255);
 *
 * @author Paul Stanton <p.m.s.stanton@leeds.ac.uk>
 * 
 * @param string $imageURL The image filename.
 * @return string HTML string containing marked-up license data.
 */
function imageLicense($image_url) {
  // Make sure that we have access to the JaduMultimediaItems class
  require_once('multimedia/JaduMultimediaItems.php');

  /* Retrieve the JaduMultimediaItems.id (which is different to the JaduImages.id 
    of the same item). */
  $image_id = getImageProperty($image_url, 'id');

  // Grab the multimedia object based on the imageID we just got.
  $image_object = getMultimediaItemByImageID($image_id);

  // Grab the image's tags from JaduMultimediaItemTags.
  $tags = $image_object->getTags();

  /*
    Set up a pattern to match the following format:

      namespace:predicate="value"

    The namespace for image licenses will always be 'license', I'm currently
    assuming a use case along the lines of:

      license:creativecommons="(c) 2009 Greg Grossmeier, used under a Creative 
      Commons Attribution-ShareAlike license: 
      http://creativecommons.org/licenses/by-sa/3.0/"

    (note, as Jadu doesn't really convert htmlentities properly, we can't use the
    raw © symbol, as this gets removed on saving to the database, nor can we use
    &copy; as this gets converted to © the next time the record is viewed in the
    control center, then stripped on save. To get around this we'll convert any
    instances of '(c)' to © in a bit.

    The predicate will, currently, be one of two values:

      * copyright
      * creativecommons

    This allows us to display appropriate (c) or (cc) image dependant on the
    license used.
  */
  $license_pattern = '/license:([\w]+)="(.+)"/';

  // Perform the regex match, populating $matches with the values.
  preg_match($license_pattern, $tags, $matches);

  // Grab our required values from the machine tag.
  $license_type   = $matches[1]; // predicate.
  $license_string = $matches[2]; // value.

  // If either value is empty, fail.
  if (empty($license_type) || empty($license_string)) {
    return false;
  }

  // Otherwise we're good to go, pass the values to the HTML helper.
  return imageLicenseToHtml($license_type, $license_string);
}

/**
 * HTML helper for image license function.
 *
 * @param string $license_type The license type (durr).
 * @param string $license_string The actual license data.
 * @return string An HTML string ready for the browser.
 */
function imageLicenseToHtml($license_type = '', $license_string = '') {
  // Grubers' Liberal URL-matching regex.
  $url_pattern = 
    '#\b(([\w-]+://?|www[.])[^\s()<>]+(?:\([\w\d]+\)|([^[:punct:]\s]|/)))#i';

  // Wrap any match in anchor text, using backreferences.
  $url_replacement = 
    '<a href="${1}" rel="license nofollow">${1}</a>';

  // Perform the regex replacement, making links clickable.
  $license_string = preg_replace(
            $url_pattern, 
            $url_replacement, 
            $license_string
          );

  // Replace any instance of (c) or (C) with the correct HTML entity.
  $license_string = str_ireplace('(c)', '&copy;', $license_string);

  // Build the output string.
  switch ($license_type) {
    case 'creativecommons':
      $output = '<p xmlns:dct="http://purl.org/dc/terms/" 
        xmlns:cc="http://creativecommons.org/ns#">' . 
        $license_string . '</p>';
      break;
    default:
      $output = '<p>' . $license_string . '</p>';
      break;
  }

  /* Finally, wrap it up in a div, bit crude, but compartmentalises it from the
    rest of the code around Jadu */
  $output = '<div class="license ' . $license_type . '">' . $output . "</div>";

  // Send it on it's merry way.
  return $output;
}

?>