feat: Implemented transformer for the wavedrom library

[alexandruradovici]

Description

This pull request implements a transformer for the wavedrom library. It allows writing waveform diagrams in the slides.

This allows writing wavefrom diagrams using the wavedrom transformer.

```wavedrom
{signal: [
  {name: 'clk', wave: 'p.....|...'},
  {name: 'dat', wave: 'x.345x|=.x', data: ['head', 'body', 'tail', 'data']},
  {name: 'req', wave: '0.1..0|1.0'},
  {},
  {name: 'ack', wave: '1.....|01.'}
]}
```

Why

This is useful when creating engineering slides. Without this feature, users have to manually transform the waveform JSON into SVG files and include those.

Disadvantages

• wavedrom, onml and json5 dev dependencies
• onml depends on two deprecated packages

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[KermanX]

Thanks for your contribution! Can this feature be used as a standalone addon package? If not, what's the missing hook?

[alexandruradovici]

I think it can be an addon, I just don't know where to find the documentation on how to use a hook. I would be very happy to convert it.

[KermanX]

About addon writing: https://sli.dev/addons/write-an-addon

You can have setup and components folder in your addon, just like in your slides folder.

[alexandruradovici]

I saw this, but is there any API documentation?

[KermanX]

Here we can register a markdown-it plugin for waredrom: https://sli.dev/custom/config-vite#configure-internal-plugins

[alexandruradovici]

I am sorry, I still do not understand how to connect my plugin to slidev.

1. I created a new package
2. I added slidev as a dependecy

How to I make it initialize my plugin?

This is really confusing here, an API documentation and example would be great.

[antfu]

This looks very cool! But yeah I agree with @KermanX, I also think it's better to implement it as an external addon.

[KermanX]

I am sorry, I still do not understand how to connect my plugin to slidev.

1. I created a new package
2. I added slidev as a dependecy

How to I make it initialize my plugin?

This is really confusing here, an API documentation and example would be great.

There seem to be some difficulties in having a custom transformer... The priority of markdown-it plugins are too low. The preparser may help, but I don't think it is graceful enough. Maybe we need a setupTransformers like this:

type MarkdownTransfromer = (ctx: MarkdownTransformContext) => void
type TransformersSetup = (transformers: MarkdownTransfromer[]) => MarkdownTransfromer[]

[KermanX]

Sorry for the late reply. These days several refactors are done and I've tested that after #1767 got merged, this PR can be implemented as an add-on in a simple way.