XHTML and template.php

Since I use inline SVG in all of my sites, I need to serve my pages up as XHTML. I couldn’t find a Drupal module or option that triggers Drupal to serve the pages up as XHTML, so I added the following code at the very top of the page.tpl.php page:

header("Vary: Accept");
if (stristr($_SERVER["HTTP_ACCEPT"], "application/xhtml+xml"))
    header("Content-Type: application/xhtml+xml; charset=utf-8");
    header("Content-Type: text/html; charset=utf-8");

All this code does is check whether the user agent can support XHTML. If it can, the page is served up as XHTML; otherwise HTML. Using embedded PHP in page.tpl.php for the theme works as desired. However, the content type of the page no longer agrees with the content-type meta element, which is included within the $head variable.

    <title><?php print $head_title ?></title>
    <?php print $head ?>
    <?php print $styles ?>
    <?php print $scripts ?>
    <!--[if lt IE 7]>
      <?php print phptemplate_get_ie_styles(); ?>

One solution would be to not print out the $head variable and just hard code all of the head entries. However, when you add a new module, such as the RDF module, which adds entries to the $head variable, you either have to hard code these in, also, or you lose functionality.

Instead, I used the template.php file, which is used to override default Drupal behavior. Specifically, I created a variant of _preprocess_page for my subtheme, used this to access $head, and alter it.

function flame_preprocess_page(&$vars) {
  $head = $vars['head'];
  $head = str_replace("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\" />",
              "<meta http-equiv=\"Content-Type\" content=\"application/xhtml+xml; charset=UTF-8\" />", $head);

  $head = str_replace("<link rel=\"alternate\" type=\"application/rss+xml\" title=\"Burningbird's RealTech RSS\" href=\"http://realtech.burningbird.net/rss.xml\" />\n","",$head);

  $vars['head'] = $head;

I am still getting my head around customization in Drupal, and will have a follow-up posting later, after I’ve had more time to work through issues. In the meantime, from my understanding, the _preprocess_page passes in an array of system variables, each of which can be accessed and altered, as I’ve done in the code example. The subtheme naming is essential, otherwise I would overwrite the use of the function within the Garland theme.

There is another theme specific function for overriding variables called _phptemplate_variables, but I gather that was Drupal 5 and the approach I used is Drupal 6.x and forward.

Now, the head entries are as I want them, and modules such as RDF can add their entries without me impacting on their work. More importantly, with the addition of the XHTML support, I can add inline SVG and the SVG will display correctly for those browsers that support inline SVG.

(Note this image is now included using the IMG element. I’m now using WordPress, and WordPress does not allow inline SVG.)

hello world in svg

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