Adam, maybe an easier way to do this would be using Extension:NamespaceHTML -- it allows HTML tags to be used, but only in a namespace of your choice. This namespace would be only editable by a trusted group. But the results could be transincluded into other namespaces, but general users still can't use raw HTML themselves.

Using the tag function #{{tag:html| you can even have Mediawiki variables inside the formatted HTML, but the HTML, itself, will not be editable by general users. Seems an easy way to go than writing a whole new extension.

Chris

Sent from my iPad

On Dec 19, 2015, at 8:00 PM, Adam Nielsen a.nielsen@shikadi.net wrote:

Hi all,

I'd like to write an extension that allows wiki pages to contain SVG code (which can be edited like any other page - templates can be used, version history is kept, etc.) I would then like to be able to embed these pages inside others, so the SVG code is then rendered as an image elsewhere on the wiki.

I am a little unsure on the best way to do this, so I'd appreciate any pointers.

I think it is best not to repurpose the File: namespace for this, because that will avoid having to deal with the difference between wikitext, files, and figuring out where template replacements should happen, so I guess a new SVG: namespace would be best.

The problem is then how to embed these images in other pages. I would like to keep to existing syntax as closely as possible, so something like [[SVG:Example]] would display the image, just like [[File:Example.png]] would.

I tried using the LinkBegin hook, replacing the wikitext with an <img> tag that links to the ?action=raw version of the SVG: page. This does work, but I lose all the standard MW image formatting methods, like being able to specify the image size or add a caption, so this isn't ideal.

In an attempt to maintain access to this formatting code, I tried hooking ImageBeforeProduceHTML instead, and using wikicode like [[File:SVG:Example]]. This will show the image, but the hook runs before all the formatting takes place so I still lose access to the MW image formatting code.

It seems like it would be better to hook in at a lower level, so the existing [[File:blah]] code runs per normal, providing resizing/caption support per normal. I'm not sure how best to do this though.

One method that comes to mind is hooking ImageBeforeProduceHTML, then writing the processed wikitext to a temporary .svg file, and returning that in the ImageBeforeProduceHTML $file parameter. However I am not sure how to do this, and guessing it may not work anyway as the final HTML code would probably have an <img> link pointing to the temporary file, which by then would have been deleted.

But in theory this idea would also allow thumbnails to be generated for browsers that don't support SVG, giving the best user experience.

Can anyone point me in the right direction for how this kind of extension could be implemented? It looks like the most reliable way is going to be an extension that can somehow make the processed wikitext from an article appear to MW as if it's an image file just like any other.

Thanks, Adam.

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There was an attempt a while ago to allow modules from the Scribunto extension (which are written in Lua, not plain wikitext, though) to render as images: https://gerrit.wikimedia.org/r/#/c/113759/

There's also https://www.mediawiki.org/wiki/Extension:GraphViz (not to be confused with Extension:Graph), which renders images from wikitext and uploads them back to the wiki as regular files in File: namespace.

Perhaps one of these will serve as inspiration :)