client_hints-8.x-1.0-alpha3/modules/client_hints_everywhere/client_hints_everywhere.module

<?php

/**
 * Implements template_preprocess_image().
 */
function client_hints_everywhere_preprocess_image(&$variables) {
  // Set processed url as clientHintsSrc data attribute.
  $variables['attributes']['data-client-hints-src'] = $variables['uri'];
  // Set an appropriately sized transparent svg as placeholder image.
  $variables['attributes']['src'] = _client_hints_placeholder_svg($variables['width'], $variables['height']);

  // Add Javascript library.
  $variables['#attached']['library'][] =  'client_hints/lazy';
}

/**
 * Implements hook_theme_registry_alter().
 */
function client_hints_everywhere_theme_registry_alter(&$theme_registry) {
  $theme_registry['image']['path'] = \Drupal::service('module_handler')->getModule('client_hints_everywhere')->getPath() . '/templates';
}