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<?php |
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|
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if (!defined('ABSPATH')) die('No direct access allowed'); |
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|
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if (!class_exists('WPO_WebP_Self_Test')) : |
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|
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class WPO_WebP_Self_Test { |
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|
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/** |
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* Relative path to the test image used for WebP serving verification. |
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* |
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* @var string |
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*/ |
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const TEST_IMAGE_PATH = '/wpo/images/wpo_logo_small.png'; |
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|
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/** |
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* The MIME type for WebP images, used as the Accept header value |
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* and for content-type verification. |
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* |
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* @var string |
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*/ |
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const WEBP_MIME_TYPE = 'image/webp'; |
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|
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/** |
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* Determines whether the content-type header indicates a WebP image. |
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* |
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* @param array<string, string> $headers An array of response headers |
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* |
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* @return bool |
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*/ |
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private function has_webp_mime($headers): bool { |
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return isset($headers['content-type']) && 0 === strcasecmp(self::WEBP_MIME_TYPE, $headers['content-type']); |
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} |
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|
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/** |
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* Determines whether the Vary header includes Accept. |
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* |
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* @param array<string, string> $headers An array of response headers |
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* |
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* @return bool |
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*/ |
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private function has_vary($headers): bool { |
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return isset($headers['vary']) && preg_match('/accept/i', $headers['vary']); |
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} |
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|
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/** |
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* Determines whether a WebP version is served when requested with |
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* an appropriate Accept header. |
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* |
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* @return bool |
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*/ |
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public function is_webp_served(): bool { |
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$args = array( |
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'headers' => array( |
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'accept' => self::WEBP_MIME_TYPE |
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) |
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); |
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|
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$upload_dir = wp_upload_dir(); |
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$url = $upload_dir['baseurl'] . self::TEST_IMAGE_PATH; |
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|
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$response = wp_remote_head($url, $args); |
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|
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if (is_wp_error($response) || 200 !== $response['response']['code']) { |
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return false; |
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} |
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|
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$headers = wp_remote_retrieve_headers($response); |
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if (is_object($headers) && method_exists($headers, 'getAll')) { |
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$headers = $headers->getAll(); |
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return $this->has_webp_mime($headers) && $this->has_vary($headers); |
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} |
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return false; |
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} |
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|
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/** |
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* Returns singleton instance |
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* |
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* @return WPO_WebP_Self_Test |
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*/ |
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public static function get_instance(): self { |
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static $_instance = null; |
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if (null === $_instance) { |
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$_instance = new self(); |
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} |
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return $_instance; |
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} |
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} |
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|
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endif; |
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|
