true, Extension::ANIM => true, Extension::BRIGHTCOVE => true, Extension::DAILYMOTION => true, Extension::FACEBOOK => true, Extension::GFYCAT => true, Extension::IFRAME => true, Extension::IMGUR => true, Extension::INSTAGRAM => true, Extension::PINTEREST => true, Extension::REDDIT => true, Extension::TWITTER => true, Extension::VIDEO => true, Extension::VIDEO_IFRAME => true, Extension::VIMEO => true, Extension::WISTIA_PLAYER => true, Extension::YOUTUBE => true, ]; /** * XPath query to relatively fetch all noscript > img elements. * * @var string */ const NOSCRIPT_IMG_XPATH_QUERY = './noscript/img'; /** * Regular expression pattern to extract the URL from a CSS background-image property. * * @var string */ const CSS_BACKGROUND_IMAGE_URL_REGEX_PATTERN = '/background-image\s*:\s*url\(\s*(?[^)]*\s*)/i'; /** * Configuration store to use. * * @var TransformerConfiguration */ private $configuration; /** * Reference node to attach preload links to. * * @var Element|null */ private $preloadReferenceNode; /** * Inline style backup attribute that stores inline styles that are being moved to