image_style_generate

Versions

mediamosa-21

image_style_generate()

Menu callback; Given a style and image path, generate a derivative.

This menu callback is always served after checking a token to prevent generation of unnecessary images. After generating an image transfer it to the requesting agent via file_transfer().

Code

modules/image/image.module, line 585

<?php
function image_style_generate() {
  $args = func_get_args();
  $style = array_shift($args);
  $style_name = $style['name'];
  $scheme = array_shift($args);
  $path = implode('/', $args);

  $path = $scheme . '://' . $path;
  $path_md5 = md5($path);
  $destination = image_style_path($style['name'], $path);

  // Check that it's a defined style and that access was granted by
  // image_style_url().
  if (!$style || !cache_get('access:' . $style_name . ':' . $path_md5, 'cache_image')) {
    drupal_access_denied();
    drupal_exit();
  }

  // Don't start generating the image if the derivate already exists or if
  // generation is in progress in another thread.
  $lock_name = 'image_style_generate:' . $style_name . ':' . $path_md5;
  if (!file_exists($destination)) {
    $lock_acquired = lock_acquire($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('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.
  $success = file_exists($destination) || image_style_create_derivative($style, $path, $destination);

  if (!empty($lock_acquired)) {
    lock_release($lock_name);
  }

  if ($success) {
    $image = image_load($destination);
    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' => $destination));
    drupal_add_http_header('Status', '500 Internal Server Error');
    print t('Error generating image.');
    drupal_exit();
  }
}
?>