A progressive image loader for Silverstripe 4

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v1.2.2 2023-03-23 04:06 UTC

This package is auto-updated.

Last update: 2024-03-23 06:24:58 UTC


Archiving soon

🪦 As all evergreen browsers now support the loading="lazy" attribute, no further feature updates will be made to this module.

We recommend uninstalling this module and replacing any progessive image variables with the standard Silverstripe equivalent in your project templates.

More: https://caniuse.com/loading-lazy-attr


This module does progressive image loading using IntersectionObserver (v1).

Browser support for IntersectionObserver (currently all the important ones).

While the module does add loading="lazy" to img tags, this module provides a polyfill for browsers that don't yet support image lazy loading natively (tl;dr Safari).


The only supported method of installing this module is via composer

composer require nswdpc/silverstripe-progressive-image


Call the thumbnail rendering methods directly within your template:

<% with $Image %>
<% end_with %>

In place of

<% with $Image %>
<% end_with %>


When one of the $Progressive* methods is called, Requirements will automatically be added via the Requirements API, these are loaded via data: uris with SRI hashes supplied


    ProgressiveImage.ss -> template containing HTML loading the image
    Script.ss -> provides the JS to handle image replacement
    Style.ss -> provides CSS to assist with image replacement

How it works

A thumbnail with 10% of the width/height of the requested size and a quality of 1 will be created. This will be the main image to load.

The final image will be created using the requested size and quality (420x280 @ 80% quality in the ProgressiveFill example above)

When the page loads, the tiny, low quality image will display by default, once the image scrolls or appears in the viewport, the larger image will load, thanks to IntersectionObserver.


Supported thumbnailing methods:

Inline script and css removal

To support Content Security Policies (CSP), the controller extension loading inline scripts and css plus related templates have been removed.






We welcome bug reports, pull requests and feature requests on the Github Issue tracker for this project.

Please review the code of conduct prior to opening a new issue.


If you have found a security issue with this module, please email digital[@]dpc.nsw.gov.au in the first instance, detailing your findings.

Development and contribution

If you would like to make contributions to the module please ensure you raise a pull request and discuss with the module maintainers.

Please review the code of conduct prior to completing a pull request.