#553944 follow-up by David_Rothstein: Allow modules to override per-page custom themes.

2 files changed, 40 insertions, 10 deletions

diff --git a/includes/menu.inc b/includes/menu.inc
index 3bb996243..5362aafd9 100644
--- a/includes/menu.inc
+++ b/includes/menu.inc
@@ -1505,8 +1505,8 @@ function menu_get_active_help() {
  *
  * @param $initialize
  *   This parameter should only be used internally; it is set to TRUE in order
- *   to force the custom theme to be initialized from the menu router item for
- *   the current page.
+ *   to force the custom theme to be initialized for the current page request.
+ *
  * @return
  *   The machine-readable name of the custom theme, if there is one.
  *
@@ -1517,9 +1517,23 @@ function menu_get_custom_theme($initialize = FALSE) {
   // Skip this if the site is offline or being installed or updated, since the
   // menu system may not be correctly initialized then.
   if ($initialize && !_menu_site_is_offline(TRUE) && (!defined('MAINTENANCE_MODE') || (MAINTENANCE_MODE != 'update' && MAINTENANCE_MODE != 'install'))) {
-    $router_item = menu_get_item();
-    if (!empty($router_item['access']) && !empty($router_item['theme_callback']) && function_exists($router_item['theme_callback'])) {
-      $custom_theme = call_user_func_array($router_item['theme_callback'], $router_item['theme_arguments']);
+    // First allow modules to dynamically set a custom theme for the current
+    // page. Since we can only have one, the last module to return a valid
+    // theme takes precedence.
+    $custom_themes = array_filter(module_invoke_all('custom_theme'), 'drupal_theme_access');
+    if (!empty($custom_themes)) {
+      $custom_theme = array_pop($custom_themes);
+    }
+    // Otherwise, execute the theme callback function for the current page, if
+    // there is one, in order to determine the custom theme to set.
+    if (!isset($custom_theme)) {
+      $router_item = menu_get_item();
+      if (!empty($router_item['access']) && !empty($router_item['theme_callback']) && function_exists($router_item['theme_callback'])) {
+        $theme_name = call_user_func_array($router_item['theme_callback'], $router_item['theme_arguments']);
+        if (drupal_theme_access($theme_name)) {
+          $custom_theme = $theme_name;
+        }
+      }
     }
   }
   return $custom_theme;
diff --git a/includes/theme.inc b/includes/theme.inc
index afab19a22..eeb7a5faf 100644
--- a/includes/theme.inc
+++ b/includes/theme.inc
@@ -41,12 +41,28 @@ define('MARK_UPDATED', 2);
  * Determines if a theme is available to use.
  *
  * @param $theme
- *   An object representing the theme to check.
+ *   Either the name of a theme or a full theme object.
+ *
  * @return
  *   Boolean TRUE if the theme is enabled or is the site administration theme;
  *   FALSE otherwise.
  */
 function drupal_theme_access($theme) {
+  if (is_object($theme)) {
+    return _drupal_theme_access($theme);
+  }
+  else {
+    $themes = list_themes();
+    return isset($themes[$theme]) && _drupal_theme_access($themes[$theme]);
+  }
+}
+
+/**
+ * Helper function for determining access to a theme.
+ *
+ * @see drupal_theme_access()
+ */
+function _drupal_theme_access($theme) {
   $admin_theme = variable_get('admin_theme');
   return !empty($theme->status) || ($admin_theme && $theme->name == $admin_theme);
 }
@@ -67,12 +83,12 @@ function drupal_theme_initialize() {
 
   // Only select the user selected theme if it is available in the
   // list of themes that can be accessed.
-  $theme = !empty($user->theme) && isset($themes[$user->theme]) && drupal_theme_access($themes[$user->theme]) ? $user->theme : variable_get('theme_default', 'garland');
+  $theme = !empty($user->theme) && drupal_theme_access($user->theme) ? $user->theme : variable_get('theme_default', 'garland');
 
-  // Allow modules to override the present theme... only select custom theme
-  // if it is available in the list of themes that can be accessed.
+  // Allow modules to override the theme. Validation has already been performed
+  // inside menu_get_custom_theme(), so we do not need to check it again here.
   $custom_theme = menu_get_custom_theme();
-  $theme = $custom_theme && isset($themes[$custom_theme]) && drupal_theme_access($themes[$custom_theme]) ? $custom_theme : $theme;
+  $theme = !empty($custom_theme) ? $custom_theme : $theme;
 
   // Store the identifier for retrieving theme settings with.
   $theme_key = $theme;