function image_style_deliver
image_style_deliver($style, $scheme)
Page callback: Generates a derivative, given a style and image path.
After generating an image, transfer it to the requesting agent.
Parameters
$style: The image style
$scheme: The file scheme, for example 'public' for public files.
File
- modules/image/image.module, line 807
- Exposes global functionality for creating image styles.
Code
function image_style_deliver($style, $scheme) { $args = func_get_args(); array_shift($args); array_shift($args); $target = implode('/', $args); // Check that the style is defined, the scheme is valid, and the image // derivative token is valid. (Sites which require image derivatives to be // generated without a token can set the 'image_allow_insecure_derivatives' // variable to TRUE to bypass the latter check, but this will increase the // site's vulnerability to denial-of-service attacks. To prevent this // variable from leaving the site vulnerable to the most serious attacks, a // token is always required when a derivative of a derivative is requested.) $valid = !empty($style) && file_stream_wrapper_valid_scheme($scheme); if (!variable_get('image_allow_insecure_derivatives', FALSE) || strpos(ltrim($target, '\/'), 'styles/') === 0) { $valid = $valid && isset($_GET[IMAGE_DERIVATIVE_TOKEN]) && $_GET[IMAGE_DERIVATIVE_TOKEN] === image_style_path_token($style['name'], $scheme . '://' . $target); } if (!$valid) { return MENU_ACCESS_DENIED; } $image_uri = $scheme . '://' . $target; $derivative_uri = image_style_path($style['name'], $image_uri); // If using the private scheme, let other modules provide headers and // control access to the file. if ($scheme == 'private') { if (file_exists($derivative_uri)) { file_download($scheme, file_uri_target($derivative_uri)); } else { $headers = file_download_headers($image_uri); if (empty($headers)) { return MENU_ACCESS_DENIED; } if (count($headers)) { foreach ($headers as $name => $value) { drupal_add_http_header($name, $value); } } } } // Confirm that the original source image exists before trying to process it. if (!is_file($image_uri)) { watchdog('image', 'Source image at %source_image_path not found while trying to generate derivative image at %derivative_path.', array('%source_image_path' => $image_uri, '%derivative_path' => $derivative_uri)); return MENU_NOT_FOUND; } // Don't start generating the image if the derivative already exists or if // generation is in progress in another thread. $lock_name = 'image_style_deliver:' . $style['name'] . ':' . drupal_hash_base64($image_uri); if (!file_exists($derivative_uri)) { $lock_acquired = lock_acquire($lock_name); if (!$lock_acquired) { // Tell client to retry again in 3 seconds. Currently no browsers are known // to support Retry-After. drupal_add_http_header('Status', '503 Service Unavailable'); drupal_add_http_header('Content-Type', 'text/html; charset=utf-8'); drupal_add_http_header('Retry-After', 3); print t('Image generation in progress. Try again shortly.'); drupal_exit(); } } // Try to generate the image, unless another thread just did it while we were // acquiring the lock. $success = file_exists($derivative_uri) || image_style_create_derivative($style, $image_uri, $derivative_uri); if (!empty($lock_acquired)) { lock_release($lock_name); } if ($success) { $image = image_load($derivative_uri); file_transfer($image->source, array('Content-Type' => $image->info['mime_type'], 'Content-Length' => $image->info['file_size'])); } else { watchdog('image', 'Unable to generate the derived image located at %path.', array('%path' => $derivative_uri)); drupal_add_http_header('Status', '500 Internal Server Error'); drupal_add_http_header('Content-Type', 'text/html; charset=utf-8'); print t('Error generating image.'); drupal_exit(); } }
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Licensed under the GNU General Public License, version 2 and later.
Drupal is a registered trademark of Dries Buytaert.
https://api.drupal.org/api/drupal/modules!image!image.module/function/image_style_deliver/7.x