hugo-geekblog/layouts/shortcodes/img.html

{{ $source := ($.Page.Resources.ByType "image").GetMatch (printf "*%s*" (.Get "name")) }}
{{ $customAlt := .Get "alt" }}
{{ $customSize := .Get "size" }}

{{ with $source }}
{{ $caption := default .Title $customAlt }}

{{ $tiny := (.Resize "320x").RelPermalink }}
{{ $small := (.Resize "600x").RelPermalink }}
{{ $medium := (.Resize "1200x").RelPermalink }}
{{ $large := (.Resize "1800x").RelPermalink }}

{{ $size := dict "tiny" $tiny "small" $small "medium" $medium "large" $large }}

<div class="flex justify-center">
<figure class="gblog-post__figure">
    <a href="{{ .RelPermalink }}">
        <img
            {{ with $customSize }}
            src="{{ index $size $customSize }}" alt="{{ $caption }}"
            {{ else }}
            srcset="{{ $size.tiny }} 320w,
                    {{ $size.small }} 600w,
                    {{ $size.medium }} 1200w,
                    {{ $size.large }} 2x"
            sizes="(max-width: 320px) 320w,
                   (max-width: 600px) 600w,
                   (max-width: 1200px) 1200w,
                   2x"
            src="{{ $size.large }}" alt="{{ $caption }}"
            {{ end }}/>
    </a>
    {{ with $caption }}
    <figcaption>{{ . }}{{ with $source.Params.credits }} ({{ . | markdownify }}){{ end }}</figcaption>
    {{ end }}
</figure>
</div>
{{ end }}