feat(shortcode): add lightbox option to Figure (#1146)

Example: `{{< figure src="example.png" lightbox="true" >}}`

layouts/shortcodes/figure.html

@@ -3,10 +3,17 @@
 {{ if .Get "library" }}
   {{ $image_src = printf "img/%s" $image_src | relURL }}
 {{ end }}
+{{ $lightbox := eq (.Get "lightbox" | default "false") "true" }}
+{{ $group := .Get "lightbox-group" | default "" }}
+
 <figure{{ with .Get "class" }} class="{{.}}"{{ end }}>
-{{ if .Get "link"}}<a href="{{ .Get "link" }}"{{ with .Get "target" }} target="{{ . }}"{{ end }}{{ with .Get "rel" }} rel="{{ . }}"{{ end }}>{{ end }}
-<img src="{{ $image_src }}" {{ if or (.Get "alt") (.Get "caption") }}alt="{{ with .Get "alt"}}{{.}}{{else}}{{ .Get "caption" }}{{ end }}" {{ end }}{{ with .Get "width" }}width="{{.}}" {{ end }}{{ with .Get "height" }}height="{{.}}" {{ end }}/>
-{{ if .Get "link"}}</a>{{ end }}
+{{ if $lightbox }}
+  <a data-fancybox="{{$group}}" href="{{$image_src}}" {{ with .Get "caption"}}data-caption="{{ .|markdownify|emojify }}"{{ end }}>
+{{ else if .Get "link"}}
+  <a href="{{ .Get "link" }}"{{ with .Get "target" }} target="{{.}}"{{ end }}{{ with .Get "rel" }} rel="{{.}}"{{ end }}>
+{{ end }}
+<img src="{{$image_src}}" {{ if or (.Get "alt") (.Get "caption") }}alt="{{ with .Get "alt"}}{{.}}{{else}}{{ .Get "caption" }}{{ end }}" {{ end }}{{ with .Get "width" }}width="{{.}}" {{ end }}{{ with .Get "height" }}height="{{.}}" {{ end }}>
+{{ if or $lightbox (.Get "link") }}</a>{{ end }}
 {{ if or (or (.Get "title") (.Get "caption")) (.Get "attr")}}
 {{ $figure := split (i18n "figure" | default "Figure %d:") "%d" }}
 <figcaption data-pre="{{ index $figure 0 }}" data-post="{{ index $figure 1 }}" {{ if eq (.Get "numbered") "true" }}class="numbered"{{ end }}>
@@ -19,4 +26,4 @@
   </p> {{ end }}
 </figcaption>
 {{ end }}
-</figure>
+</figure>