Would it be possible to use the standard Markdown syntax for images?

[nhoizey]

I have put the question on StackOverflow first, so this is almost a copy/paste:

I would like to use the Jekyll Responsive Image plugin to generate appropriate responsive images with srcset/sizes attributes for my posts' images. That's why I'm here obviously… ;-)

But I would also like to be able to edit my posts in a software providing a live preview like MacDown, which only understands the standard Markdown syntax for images.

That's why I would like to know if there is a way —in this plugin or another one— to tell Jekyll to transform the standard Markdown syntax for images, which I would put in my Markdown files…

![alt text](path/to/image.jpg)

…into this syntax specific to the Jekyll Responsive Image plugin:

{% responsive_image path: path/to/image.jpg alt: "alt text" %}

And THEN, Jekyll could continue and use Kramdown to generate the HTML…

I understand I could only manage one template this way, but it should be enough for my blog.

[wildlyinaccurate]

You should be able to achieve this by writing a simple converter plugin. This should do the trick, though I don't know how performant it will be with larger sites:

module Jekyll
  class UpcaseConverter < Converter
    safe true
    priority :low

    def matches(ext)
      ext =~ /^\.md$/i
    end

    def output_ext(ext)
      ".html"
    end

    def convert(content)
      content.gsub(/\!\[(.+)\]\((.+)\)/, '{% responsive_image path: \2 alt: \1  %}')
    end
  end
end

[nhoizey]

Shouldn't the output be .md?

How does this ensure it is run before Kramdown?

[wildlyinaccurate]

output_ext is used to determine the extension of the generated file (i.e. the file in _site/). So unless you're building your site in a format other than HTML, it should probably be ".html".

If you're seeing it run after the Markdown processor, then you can bump the priority -- there's a list of priorities in the docs I linked to.

[nhoizey]

Thanks for the explanation.

It seems I could also build my converter so that it runs Kramdown after it has done its job: http://stackoverflow.com/a/26075361/717195

[nhoizey]

I think I will use @parkr 's solution: http://stackoverflow.com/a/35636071/717195

But then I still need #13 before migrating from my current use of https://github.com/nhoizey/jekyll-picture-tag …