Overriding Product Image on Product Detail without overriding media.phtml

Question

I am using magento 1.9.2.1

I am working on functionality in which I need to change Product Image Dynamically from third Part extension, It can be easily done using overriding media.phtml file.

But I am seeking for another method that can override block Mage_Catalog_Block_Product_View_Media or something like that can avoid me to change or interact with .phtml files.

EDITED

Actually, I want to give more about my Question, actually I want to change on Product Detail page without any changes in template section, or without adding or overriding any phtml file.

please let me know, Is this possible? if yes, then,Iin what way i can do this?

Answer 1

You need to change the template dynamically. For this you can observe the event controller_action_layout_generate_blocks_after and your observer should somewhat look like this.

<?php
class Magento_Study_Model_Observer
{
    const NEW_MEDIA_TEMPALTE = 'your/new/media/template.phtml';

    public function changeProductImageTemplate(Varien_Event_Observer $observer)
    {
        //get layout object from event
        $layout = $observer->getEvent()->getLayout();

        //make sure it is a product page or category page
        if (Mage::registry('current_product') != ''
            || Mage::registry('current_category') != ''
        ) { 

            //changing template
            $layout->getBlock('product.info.media')
                ->setTemplate(self::NEW_MEDIA_TEMPALTE);
        }

        return $this;
    }
}

As you can see, we are first make sure we are inside a product page. Then we grab the media block and assign a new template to it. Now all you need to do is change the constant NEW_MEDIA_TEMPLATE with your custom media template file path and then define that file and do modification there.

To find complete code reference, you can refer this answer.

EDIT

This is the layout update xml way of doing this operation

<layout>
    <catalog_category_view>
        <reference name="product.info.media">
            <action method="setTemplate">
                <template>path/to/your/custom/media.phtml</template>
            </action>
        </reference>
    </catalog_category_view>

    <catalog_product_view>
        <reference name="product.info.media">
            <action method="setTemplate">
                <template>path/to/your/custom/media.phtml</template>
            </action>
        </reference>
    </catalog_product_view>
</layout>