Drupal theme overrides for better accessibility

theme_image.php

<?php

/*
theme_image() override.
*/
function THEME_image($vars)
{
  // [Accessibility] Images must always have an alt attribute.
  if (! isset($vars['alt'])) {
    $vars['alt'] = '';
  }

  return theme_image($vars);
}

theme_link.php

<?php

/*
  theme_link() override.
*/
function THEME_link($vars)
{
  $attrs =& $vars['options']['attributes'];

  // [Accessibility] Remove href attribute for links that are the current page.
  if (!(isset($attrs['class']) && in_array('active', $attrs['class']))) {
    $url = check_plain(url($vars['path'], $vars['options']));
    $attrs['href'] = $url;
  }

  // [Accessibility] Avoid empty title attributes and 'parrot' tooltips.
  if (
    isset($attrs['title']) &&
    (! strlen($attrs['title']) || $attrs['title'] == $vars['text'])
  ) {
    unset($attrs['title']);
  }

  return '<a' . drupal_attributes($vars['options']['attributes']) . '>' .
    ($vars['options']['html'] ? $vars['text'] : check_plain($vars['text'])) .
    '</a>';
}