Lighbox does not show placeholder image from the shortcode

[cderv]

---
title: "Lightbox test"
format: html
lightbox: true
---

![Content]({{< placeholder >}})

The image won't be shown in the modal when clicking.

I think this is a bad interaction because placeholder create data-uri image, this is not correctly handled by Lightbox in the way we configure it.

placeholder shortcode will create this

<img src="data:image/png;base64,<<encoded>>" class="img-fluid figure-img" alt="Content">

Our filter do take everything to set on the link of class lightbox and especially take the src to become the href

quarto-cli/src/resources/filters/layout/lightbox.lua

Lines 105 to 106 in 6173a70

	-- wrap decorated images in a link with appropriate attrs
	local link = pandoc.Link({imgEl}, imgEl.src, title, linkAttributes)

This does not play well with Lighbox which uses the href to select the type. And href being a data uri is not ok. So it default to external type in lightbox https://github.com/biati-digital/glightbox/blob/b71340f54371169276d01f84adcfa443a917a621/src/js/core/slide-parser.js#L34-L67

which leads to using an iframe and not an image, when creating the lighbox modal. This prevent the image to show.

I believe we should correctly make this placeholder interact with lightbox. We may need to patch glightbox for that or just wait for upstream to add the feature

• Image in Base64 biati-digital/glightbox#518

(this is not a problem with embed-resources because images are encoded later in the process and the Lua filter already put href on the link using the src being a filename with extension. Then Lightbox do the right think to find back the encoded part).