support layers

[alixander]

not sure how best to do it, but just creating the issue so it's not forgotten

[BarryNolte]

The layers paradigm seems to lend itself to being represented as a separate page per layer. This could be rendered as an actual preview tab per layer, or on one preview with html rendered tabs to switch between layers. The question really being how to relay this information from d2 cli to the d2 extension.

[jlnrrg]

As layers are currently not supported, this leads to a compilation error in the vs-code preview.

For my specific use case, I build links between different d2 files, thus using the layers as link for the pdf mode.
The problem is, once I include the links, the vs-code preview does not work any longer.

Would it be possible to just ignore layers without breaking the compilation?
Or including a beta flag, that allows the vs-code preview to ignore layers, but the pdf export to use it?

[BarryNolte]

I'll take another look at this.

[BarryNolte]

@alixander What is the mode of operation in D2 Studio? How are Layers handled there?