L is not defined in leaflet-iiif

[jcoyne]

When loaded as a module. It may depend on L as a constant (via Leaflet)

https://github.com/projectblacklight/spotlight/blob/main/vendor/assets/javascripts/leaflet-iiif.js#L7

The original is in @mejackreed's repo: https://github.com/mejackreed/Leaflet-IIIF

[mejackreed]

Has an absolute hard dependency on Leaflet

[jcoyne]

Hi @mejackreed 👋 I'm wondering it it can be patched to import L from "leaflet-src.esm.js" rather than expectingL to be defined globally?

[mejackreed]

For the fork here in Spotlight, sure? Leaflet plugins usually follow a pattern to extend L from an expected global existence. Maybe there are other patterns out there to handle this?

Also, I have no understanding anymore about how Rails expects this to work 😉

// leaflet-iiif importer

import L from "leaflet-src.esm.js";
import leaflet-iiif

[jcoyne]

@mejackreed Using ESM modules seems to be the path forward for Leaflet:

import leaflet/dist/leaflet-src.esm.js explicitly instead to take advantage [of modules]; ESM by default will come in v2

https://github.com/Leaflet/Leaflet/releases/tag/v1.9.2

[jcoyne]

Here is a PR that would resolve this: mejackreed/Leaflet-IIIF#93

[taylor-steve]

Noting that:

• Justin's work here makes Leaflet-IIIF work with import maps. I've been using it in my exploratory BL8 builds in Spotlight and it works great for that. If we can't get it into the gem, we might need to make a decision (e.g., fork or apply the patch locally in Spotlight).
• @cbeer pointed out that Leaflet-IIIF is likely only used for one or two purposes in Spotlight (e.g., image cropping). Now that we're willing to introduce breaking changes, another valid approach to this ticket could be to replicate/replace that functionality using a different approach and removing the dependency on Leaflet-IIIF.

[taylor-steve]

Confirming it appears this is only used in Spotlight for the cropper in admin/crop.js.

It seems we could replicate this cropping tool using OSD or OpenLayers, but it'd be work. It might be worth waiting until we know more about sul-dlss/exhibits#357 on the off chance we need to support something beyond a fixed aspect ratio rectangle.

If the existing tool is sufficient, I'd suggest we wait until we're slightly further in the overall JS work.

[taylor-steve]

@dnoneill suggested https://github.com/annotorious/annotorious which looks promising should we want to switch to OSD.

[taylor-steve]

I think we may want to explore the replacement option for the cropper further. If it's on the order of ~1-2 days of work, it may be faster than trying to resolve all the quirks it is having in the Propshaft build.