API for extensions previewing in HTML

[mohsen1]

Like Markdown preview, I want to build extensions that preview other types of files in HTML/CSS/JS. Please open up API for this type of extensions.

[Stephanvs]

Actually I was trying to do something similar like this for my graphviz extension, I want to be able to generate some html based on the current active document and preview it in a similar way as the Markdown preview. I found the way the Markdown extension does this, but it's not available as public API's

[jrieken]

Yeah, the markdown stuff isn't an extension yet. I can think of either a special HTMLTextDocument, a mode when opening an editor, or some command. Needs some thinking...

[Stephanvs]

Also I noticed the OpenPreviewToSideAction and related Action class, which can toggle the preview mode, something like that would also be useful to do.

[jrieken]

yeah, tho that action takes undocumented context... We need to elevate it

[alefragnani]

I was also looking for this 👍
@jrieken , you could also look (when deciding the new APIs) for other supported file types, like images (png, jpg).

[jrieken]

related to #272. Idea goes like this:

1. extension creates a virtual document with Uri & content
2. have command to preview html/md from Uri

[be5invis]

And maybe the API can support more preview types, for example, TeX?