Files: wp-admin/includes/class-custom-image-header.php

Create an attachment ‘object’.

Insert an attachment and its metadata.

Gets attachment uploaded by Media Manager, crops it, then saves it as a new object. Returns JSON-encoded object details.

Display JavaScript based on Step 2.

Display first step of custom header image page.

Display second step of custom header image page.

Upload the file to be cropped in the second step.

Constructor – Register administration header callback.

Set up the hooks for the Custom Header admin page.

Adds contextual help.

Get the current step.

Set up the enqueue for the JavaScript files.

Set up the enqueue for the CSS files

Execute custom header modification.

Process the default headers