gistfile1.txt

/**
 * On the fly image cropping based on WP 3.5 image editor
 *
 * @param    int     $id
 * @param    int     $width
 * @param    int     $height
 * @param    boolean $crop
 *
 * @return   string
 */
function cv_resize( $id = 0, $width = 50, $height = 50, $crop = true ) {

  // Check if attachment is an image
  if ( ! $id || ! wp_attachment_is_image( $id ) ) {
    return false;
  }

  $size = 'cv_'.floor($width).'x'.floor($height).'_'.(string)$crop;

  if( !has_image_size($size) )
    add_image_size( $size, floor($width), floor($height), $crop );

  $upload_dir = wp_upload_dir();
  $img_meta   = wp_get_attachment_metadata( $id );
  $img_size   = !empty( $img_meta['sizes'][$size] ) ? $img_meta['sizes'][$size] : false;

  $original_file_name = wp_basename($img_meta['file']);
  $new_file_name = str_replace($original_file_name, $img_size['file'], $img_meta['file']);

  $file = $upload_dir['basedir'] . '/' . $img_meta['file'];

  if( !empty($img_size) && ( $img_size['width'] == floor($width) ) && file_exists($upload_dir['basedir'] . '/' . $new_file_name) ) {
    return $upload_dir['baseurl'] . '/' . $new_file_name.'#existed';
  }

  $image = wp_get_image_editor( $file );

  // legacy error explanation.
  if ( is_wp_error( $image ) ) {
    return false;
  }
  require_once ( ABSPATH . 'wp-admin/includes/image.php' );

  // generate intended file name and check if the image exists.
  $new_file_path = $image->generate_filename( $suffix = $width . 'x' . $height );

  // resize image and save
  $image->resize( $width, $height, $crop );
  $new_image_info = $image->save();

  // legacy error explanation.
  if ( is_wp_error( $new_image_info ) ) {
    return false;
  }

  $attach_data = wp_generate_attachment_metadata( $id, $file );

  wp_update_attachment_metadata( $id, $attach_data );

  // convert path to url
  $url = str_replace( $upload_dir['basedir'], $upload_dir['baseurl'], $new_image_info['path'] );

  return $url.'#new';
}