erynwells.me/layouts/partials/photos/thumbnail.html

{{- $thumbnailResource := .Page.Resources.GetMatch
                            (index .Page.Params "thumbnail" | default "[tT]humbnail*")
                        | default (index (.Page.Resources.ByType "image") 0) -}}

{{- if not $thumbnailResource -}}
  {{- errorf "No thumbnail available for %s" .Page.Permalink }}
{{- end -}}

{{ $orientation := partial "images/orientation_angle.html" $thumbnailResource }}

{{ $targetWidth := 0 }}
{{ if isset . "Width" }}
  {{ $targetWidth = .Width }}
{{ else }}
  {{ $targetWidth = $thumbnailResource.Width }}
{{ end }}

{{ $targetHeight := 0 }}
{{ if isset . "Height" }}
  {{ $targetHeight = .Height }}
{{ else }}
  {{ $targetHeight = $thumbnailResource.Height }}
{{ end }}

{{ $thumbnail := false }}
{{ if not (and (eq $orientation 0)
               (eq $targetWidth $thumbnailResource.Width)
               (eq $targetHeight $thumbnailResource.Height)) }}
  {{ $thumbnail = $thumbnailResource.Fit (printf "%dx%d r%d" $targetWidth $targetHeight (sub 360 $orientation)) }}
{{ else }}
  {{ $thumbnail = $thumbnailResource }}
{{ end }}

{{ return $thumbnail }}