[blog] http://jacques.sh/ajouter-un-handle-personnalise-sur-une-page-sur-magento.html

index.php

<?php
Zend_Debug::dump(Mage::app()->getLayout()->getUpdate()->getHandles());

load_layout.php

<?php
abstract class Mage_Core_Controller_Varien_Action
{
    /* .. */

    /**
     * Load layout by handles(s)
     *
     * @param   string $handles
     * @param   string $cacheId
     * @param   boolean $generateBlocks
     * @return  Mage_Core_Controller_Varien_Action
     */
    public function loadLayout($handles=null, $generateBlocks=true, $generateXml=true)
    {
        // if handles were specified in arguments load them first
        if (false!==$handles && ''!==$handles) {
            // The $handles can be a string or an array
            $this->getLayout()->getUpdate()->addHandle($handles ? $handles : 'default');
        }

        /*
         * Add default layout handles for this action
         */
        //$this->addActionLayoutHandles();
        // -- copy of addActionLayoutHandles() --

        $update = $this->getLayout()->getUpdate();

        // load store handle
        $update->addHandle('STORE_'.Mage::app()->getStore()->getCode());

        // load theme handle
        $package = Mage::getSingleton('core/design_package');
        $update->addHandle('THEME_'.$package->getArea().'_'.$package->getPackageName().'_'.$package->getTheme('layout'));

        // load action handle
        // The method getFullActionName() returns "frontname_controller_action" in our example
        $update->addHandle(strtolower($this->getFullActionName()));

        // -- endcopy of addActionLayoutHandles() --

        /*
         * Load the updates of the Layout
         */
        //$this->loadLayoutUpdates();
        // -- copy of loadLayoutUpdates() --

        // dispatch event for adding handles to layout update
        Mage::dispatchEvent(
            'controller_action_layout_load_before',
            array('action'=>$this, 'layout'=>$this->getLayout())
        );

        // load layout updates by specified handles
        $this->getLayout()->getUpdate()->load();

        // -- endcopy of loadLayoutUpdates() --

        if (!$generateXml) {
            return $this;
        }
        $this->generateLayoutXml();

        if (!$generateBlocks) {
            return $this;
        }
        $this->generateLayoutBlocks();
        $this->_isLayoutLoaded = true;

        return $this;
    }

    /* .. */

}

observer_dispatch.php

<?php

class Mon_Module_Model_Observer
{
    /**
     * Add handles before the layout xml generation
     * @param Varien_Event_Observer $observer
     * @return void
     */
    public function layoutLoadBefore(Varien_Event_Observer $observer)
    {
        if ($action = $observer->getAction()) {
            Mage::dispatchEvent(
              'controller_action_layout_load_before_' . $action->getFullActionName(),
              $observer->getData()
            );
        }
    }
    
}

observer_handle.php

<?php

class Mon_Module_Model_Observer
{
    /**
     * Add handles before the layout xml generation
     * @param Varien_Event_Observer $observer
     * @return void
     */
    public function layoutLoadBefore(Varien_Event_Observer $observer)
    {
        if ($action = $observer->getAction()) {
            switch ($action->getFullActionName()) {
                case 'frontname_controller_action':
                    $observer->getLayout()->getUpdate()->addHandle('MON_NEW_HANDLE');
                    break;
            }
        }
    }
    
}

observer_news.php

<?php

class Mon_Module_Model_Observer
{
    /**
     * Add handles before the layout xml generation
     * @param Varien_Event_Observer $observer
     * @return void
     */
    public function layoutLoadBefore(Varien_Event_Observer $observer)
    {
        if ($action = $observer->getAction()) {
            switch ($action->getFullActionName()) {
                case 'frontname_controller_action':
                    $news = Mage::registry('current_news');
                    if ($news->getId()) {
                        $observer->getLayout()->getUpdate()->addHandle('MON_MODULE_ACTION_NEWS_TYPE_' . $news->getType());
                    }
                    break;
            }
        }
    }
    
}