EDIT

 *    an array of mimetypes in their order of preference. e.g:

 *    array('application/pdf', 'image/png', 'image/jpeg', 'image/gif', 'text/html')

 *    The width of the optimal image. If null, the method will return the representation with the biggest expanse

 *    The height of the optimal image. If null, the method will return the representation with the biggest expanse

        $expanseDeltaSum = 0;

          if (empty($part->uri)) {

          $expanseDelta = PHP_INT_MAX; // biggest delta for unkown sizes

          // determine the optimal size

            $expanse = $part->width * $part->height;

            if ($width != null && $height != null) {

              $optimalExpanse = $height * $width;

            } else {

              $optimalExpanse = PHP_INT_MAX;

            }

            // determine the difference

            $expanseDelta = $expanse > $optimalExpanse ? $expanse - $optimalExpanse : $optimalExpanse - $expanse;

          // sum up the expanseDeltas of all parts contained in the representation

          $expanseDeltaSum += $expanseDelta;

          $expanseDeltaSum = $expanseDeltaSum / $valid_parts_cnt;

          $prefRepr[$expanseDeltaSum . '_'] = $representation;

  // Sort the array so that the smallest key value is the first in the array

  ksort($prefRepr);

  // Determine which representation and which part to show

  if (!$mediarepresentation_uuid) {

    $representations = cdm_preferred_media_representations($media, array('image/png', 'image/jpeg', 'image/gif'), null, null);

    $mediarepresentation_uuid = isset($representations[0]) ? $representations[0]->uuid : null;

  }

  $p_i = 0;

  foreach ($media->representations as $representation) {

    if ($representation->uuid == $mediarepresentation_uuid) {

      $representationIdx = $p_i;

    $p_i++;