support providing a metadata file

layouts/shortcodes/snap-gallery.html

@@ -18,6 +18,12 @@
 {{- $imgs := slice -}}
 {{- $img_exts := slice ".jpg" ".jpeg" ".png" ".gif" ".webp" ".tiff" -}}
 
+{{/*  Get information from optional metadata file  */}}
+{{- $metadata := dict -}}
+{{- with .Params.metadata -}}
+  {{- $metadata = index $.Site.Data . -}}
+{{- end -}}
+
 {{/*  Get images from src Param, separated by comma  */}}
 {{- range (split .Params.src ",") -}}
   {{- $img := (trim . " ") -}}
@@ -36,10 +42,19 @@
   {{- end -}}
 {{- end -}}
 
-{{/*  Filter collected files by whether they are an image. Throw others out  */}}
+{{/*  Filter collected files, store them as slice of dicts/maps  */}}
 {{- range $imgs_collect -}}
+  {{/*  Only process files if they are recognised as an image  */}}
   {{- if in $img_exts (lower (path.Ext .)) -}}
-    {{- $imgs = $imgs | append . -}}
+    {{/*  Create a dict holding path and optional metadata  */}}
+    {{- $imgdict := dict "src" . -}}
+    {{/*  If metadata for this image path found, add all of it to dict  */}}
+    {{- $img_metadata := where $metadata "src" . -}}
+    {{- with $img_metadata -}}
+      {{- $imgdict = merge $imgdict (index . 0) -}}
+    {{- end -}}
+    {{/*  Add final dict to slice  */}}
+    {{- $imgs = $imgs | append $imgdict -}}
   {{- end -}}
 {{- end -}}
 
@@ -63,6 +78,6 @@
 {{- end -}}
 
 {{/*  The Modal/Lightbox  */}}
-{{- if $lightbox -}}
+{{ if $lightbox -}}
 {{- partial "lightbox" (dict "galno" $galno "imgs" $imgs) -}}
 {{- end -}}