tacky render-image.html with help from hkskup

render-image.html

{{- $src := .Page.Resources.GetMatch (printf "*%s*" .Destination) }}
{{- $altText := .PlainText }}
{{- $imgTitle := replaceRE "{.*}$" "" .Title }}

{{- /*  Parse attributes  */ -}}
{{- $attrs := split ( trim ( index (findRE `{.*}` .Title ) 0 ) "{}" ) " " -}}
{{- $attributes := (dict) -}}
{{ range $attrs -}}
  {{- if index (findRE `(\#)(.+)` .) 0 -}}
    {{- /*  IDs  */ -}}
    {{- $attributes = merge $attributes ( dict "id" (slice ( trim . "#" )) ) -}}
  {{- else if  index (findRE `(\.)(.+)` .) 0 -}}
    {{- /*  Classes  */ -}}
    {{- $class := slice (trim . "." ) -}}
    {{- $current := index $attributes "class" | default (slice) -}}
    {{- $attributes = merge $attributes ( dict "class" (append $current $class) ) -}}
  {{- else if  index (findRE `(\w+)=(['"]?\w+["']?)` . ) 0 -}}
    {{- /*  Attributes  */ -}}
    {{- $attr := replaceRE `(\w+)=(['"]?\w+["']?)` `$1` . -}}
    {{- $val := split ( replaceRE `(\w+)=(['"]?(\w+)["']?)` `$3` .) " " -}}
    {{- $current := index $attributes $attr | default (slice) -}}
    {{- $attributes = merge $attributes ( dict $attr (append $current $val)) -}}
  {{- else if index (findRE `(\w+)` . ) 0 -}}
    {{/*  Booleans  */}}
    {{- $attributes = merge $attributes (dict . true) -}}
  {{- end -}}
{{- end -}}

<figure class="figure d-block text-center">
  {{- range $attr, $val := $attributes -}}
      {{- if eq $val true -}}
        {{- (print " " $attr) | safeHTMLAttr -}}
      {{- else -}}
        {{- (printf " %s=%q" $attr (delimit $val ` ` )) | safeHTML -}}
    {{- end -}}
  {{- end -}}
  {{- if $src -}}
      {{- $sizes := dict "tiny" 500 "small" 800 "medium" 1200 "large" 1500 }}
      {{- $scratch := newScratch }}
      {{- range $name, $width := $sizes }}
          {{- $scratch.Set $name ($src.Resize (printf "%dx" $width)) }}
      {{- end -}}
    <img class="figure-img img-fluid"
        src="{{ $src.Permalink }}"
        sizes="(min-width: 35em) 1200px, 100vw"
        srcset="
          {{- range $name, $width := $sizes }}
              {{- if ge $src.Width $width }}
                  {{- with $scratch.Get $name }}{{ .RelPermalink }} {{ $width }}w, {{ end }}
              {{- end }}
          {{- end }}"
  {{- else -}}
    <img class="figure-img img-fluid"
        src="{{ .Destination | safeURL }}"
  {{- end -}}
    {{- with $imgTitle }} title="{{ . }}" {{ end -}}
    {{- with .PlainText }} alt="{{ . }}" {{ end -}}
    />
  {{- with $imgTitle }}<figcaption class="figure-caption text-right">{{ . | safeHTML }}</figcaption>{{ end }}
</figure>