This extension modifies product page. It shows how to change page layout (from 1column to 2column-right)
and how to replace part of the page (Block) with new template.
To demonstrate how to customize a webpage in Magento.
View-related files in Magento are based on "application area." For instance, if the user browsing the website is in the "frontend" area - such as a customer purchasing a product - pages in the admin area cannot be loaded. The view folder contains subdirectories named by application area, which contain files only relevant to that area. This extension only deals places content on the frontend, so it only has a frontend directory.
In this example we want to modify product page.
Catalog module renders product view with controller Catalog/Product/View,
so the name of layout for this page should be catalog_product_view.xml.
The layout file defines two things:
change the page layout to 2columns-right (Catalog module declares 1column layout for this page)
and replace container product.info.media with custom one.
There can be custom or specialized block classes for sophisticated extensions, but here we use the most basic block class, Magento\Framework\View\Element\Template, to handle plain html content.
The block's template defines exactly what that content will be. The layout file defines which module contains the
template, and what its name is. Based on that, the application will look in <extension-root>/view/frontend/templates
for catalog_product_view_image.phtml. The block uses its toHtml() method to process the template file and generate output html.
This module is intended to be installed using composer.
After the code is marshalled by composer, enable the module by adding it the list of enabled modules in the config
or, if that file does not exist, installing Magento.
After including this component and enabling it, you can verify it is installed by going the backend at:
STORES -> Configuration -> ADVANCED/Advanced -> Disable Modules Output
Once there check that the module name shows up in the list to confirm that it was installed correctly.
If you already have generated static files, you need to re-generate it to copy custom images from module to publicly accessible static data.
This module doesn't contains code that can be covered with tests.
Magento Core team