Mermaid PNG support

[andreas-globi]

It would be awesome if there were PNG support for Mermaid charts. SVG is not as usable from an API point of view.

[ggrossetie]

For reference, Mermaid CLI is using screenshot from Puppeteer to generate a PNG image: https://github.com/mermaidjs/mermaid.cli/blob/46185413d75384cd7bceed802d187db6852f5190/index.js#L113-L117

[andreas-globi]

I don't understand what that means. The return is an SVG and not a PNG. Renaming it to PNG doesn't help either. Internally it's not PNG data. (sorry - don't know much about puppeteer if I'm missing something obvious here). And pushing the result into an API that accepts PNG's results in a blank image.

[ggrossetie]

I don't understand what that means. The return is an SVG and not a PNG. Renaming it to PNG doesn't help either. Internally it's not PNG data.

Sorry I wasn't clear, I was just posting a possible solution that I found.
Currently, Kroki only supports SVG for Mermaid but we could take inspiration from the Mermaid CLI and use the same technique to produce a PNG.

Another idea would be to use the browser to convert a SVG to a PNG using canvas: https://developer.mozilla.org/fr/docs/Web/API/Canvas_API

(sorry - don't know much about puppeteer if I'm missing something obvious here). And pushing the result into an API that accepts PNG's results in a blank image.

No worries, Puppeteer is a Node library that we use to run and interact with a headless Chrome browser.
To be clear I was not suggesting a workaround but a possible solution to implement this feature.

[derlin]

I am on it :)