What is the significance of parbase as cq:component's resourceSuperType

Question

I know that i require foundation/components/parbase as a sling:resourceSuperType, as Parbase allows components to inherit attributes from other components.

As an Example, i removed parbase as resourceSuperType from foundation/components/image component and the dialog was not able to load properly as seen in the Screenshot, Crop, Rotate, Clear functionality is no longer working.

I've confirmed that Ext Js library is being loaded properly for xtype 'html5SmartImage', So what extra things does foundation/components/parbase provides for this functionality ?

Answer 1

Parbase allows components to inherit attributes from other components.

The above statement is a bit wrong in my opinion. It doesn't allow you to inherit attributes from other components. Rather any component which defines foundation/components/parbase as it's parent would inherit the scripts of parbase.

If you look at the parbase component within AEM, you would find a servlet which renders an image, when the URL contains img selector. Additionally you may also find a script that caters to the selector scaffolding.

Thus, whenever you define parbase or any other component inheriting from parbase as the super type for your component, you are able to use the image rendering features without the need to write separate logic for the same.

Coming to your example of the image component, the html5smartimage makes a request to the resource using the request suffix (.img.png), which is when your Image rendering servlet kicks in and draws the image. Since you have removed parbase from the super type, you would receive a 404 for the request thereby showing empty panel. However, the buttons displayed as disabled is altogether a different issue. It's a bug/feature in AEM, that when the requested image is not found, further processing of the panel stops thereby rendering them disabled.