QueryPath::encodeDataURL PHP Method

    public static function encodeDataURL($data, $mime = 'application/octet-stream', $context = null)
    {
        if (is_resource($data)) {
            $data = stream_get_contents($data);
        } elseif (filter_var($data, FILTER_VALIDATE_URL)) {
            $data = file_get_contents($data, false, $context);
        }
        $encoded = base64_encode($data);
        return 'data:' . $mime . ';base64,' . $encoded;
    }

 /**
  * Insert or retrieve a Data URL.
  *
  * When called with just $attr, it will fetch the result, attempt to decode it, and
  * return an array with the MIME type and the application data.
  *
  * When called with both $attr and $data, it will inject the data into all selected elements
  * So @code$qp->dataURL('src', file_get_contents('my.png'), 'image/png')@endcode will inject
  * the given PNG image into the selected elements.
  *
  * The current implementation only knows how to encode and decode Base 64 data.
  *
  * Note that this is known *not* to work on IE 6, but should render fine in other browsers.
  *
  * @param string $attr
  *  The name of the attribute.
  * @param mixed $data
  *  The contents to inject as the data. The value can be any one of the following:
  *  - A URL: If this is given, then the subsystem will read the content from that URL. THIS
  *    MUST BE A FULL URL, not a relative path.
  *  - A string of data: If this is given, then the subsystem will encode the string.
  *  - A stream or file handle: If this is given, the stream's contents will be encoded
  *    and inserted as data.
  *  (Note that we make the assumption here that you would never want to set data to be
  *  a URL. If this is an incorrect assumption, file a bug.)
  * @param string $mime
  *  The MIME type of the document.
  * @param resource $context
  *  A valid context. Use this only if you need to pass a stream context. This is only necessary
  *  if $data is a URL. (See {@link stream_context_create()}).
  * @retval mixed
  *  If this is called as a setter, this will return a DOMQuery object. Otherwise, it
  *  will attempt to fetch data out of the attribute and return that.
  * @see http://en.wikipedia.org/wiki/Data:_URL
  * @see attr()
  * @since 2.1
  */
 public function dataURL($attr, $data = NULL, $mime = 'application/octet-stream', $context = NULL)
 {
     if (is_null($data)) {
         // Attempt to fetch the data
         $data = $this->attr($attr);
         if (empty($data) || is_array($data) || strpos($data, 'data:') !== 0) {
             return;
         }
         // So 1 and 2 should be MIME types, and 3 should be the base64-encoded data.
         $regex = '/^data:([a-zA-Z0-9]+)\\/([a-zA-Z0-9]+);base64,(.*)$/';
         $matches = array();
         preg_match($regex, $data, $matches);
         if (!empty($matches)) {
             $result = array('mime' => $matches[1] . '/' . $matches[2], 'data' => base64_decode($matches[3]));
             return $result;
         }
     } else {
         $attVal = \QueryPath::encodeDataURL($data, $mime, $context);
         return $this->attr($attr, $attVal);
     }
 }