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https://github.com/alanorth/hugo-theme-bootstrap4-blog.git
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93 lines
4.3 KiB
HTML
93 lines
4.3 KiB
HTML
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{{/*
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figure with auto-resizing and srcset v2020-11-30
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Drop-in replacement for Hugo's figure shortcode as of 2020-05-02 that uses img srcset
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to enable browsers to download only the resolution that they need.
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The resizing and srcset magic only works for images that are part of the page
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bundle. It will fall back to stock Hugo figure behaviour otherwise.
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Improvements that were initially out of reach of my Hugo template programming "skills"
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but have now been taken care of:
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- [x] gracefully handle images that are not in page bundle, i.e. no image processing available
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- [x] use a single configurable sizes array, and derive everything from there
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See https://cpbotha.net/2020/05/02/drop-in-replacement-for-hugo-figure-shortcode-with-img-srcset-support/
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- original srcset img shortcode from: https://laurakalbag.com/processing-responsive-images-with-hugo/
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- original hugo figure shortcode from: https://github.com/gohugoio/hugo/blob/master/tpl/tplimpl/embedded/templates/shortcodes/figure.html
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- no unnecessary resizes and more nudges by Stéfan van der Walt https://mentat.za.net/
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- mashing together and srcset logic fixes by Charl P. Botha https://cpbotha.net/
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Changes:
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- 2020-11-30 handle images that are rotated 90 degrees (should handle more eventually)
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- 2020-05-10 fall back to stock Hugo behaviour when no page bundle found
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- 2020-05-04 no unnecessary resizes, sizes in array
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- 2020-05-02 initial release
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*/}}
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{{/* hugo will resize to all of these sizes that are smaller than your original. configure if you like! */}}
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{{ $sizes := (slice "480" "800" "1200" "1500") }}
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{{/* get file that matches the filename as specified as src="" in shortcode */}}
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{{ $src := .Page.Resources.GetMatch (printf "*%s*" (.Get "src")) }}
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<figure{{ with .Get "class" }} class="{{ . }}"{{ end }}>
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{{- if .Get "link" -}}
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<a href="{{ .Get "link" }}"{{ with .Get "target" }} target="{{ . }}"{{ end }}{{ with .Get "rel" }} rel="{{ . }}"{{ end }}>
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{{- end }}
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<img
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{{ if $src }}
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sizes="(min-width: 35em) 1200px, 100vw"
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{{/* only srcset images smaller than or equal to the src (original) image size, as Hugo will upscale small images */}}
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srcset='
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{{ range $sizes }}
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{{ $size := . }}
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{{/* https://discourse.gohugo.io/t/image-exif-orientation/22902/7 */}}
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{{/* set orientation to 1 just in case it doesnt exist in Exif */}}
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{{ $orientation := 1 }}
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{{ with $src.Exif }}
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{{ $orientation := .Tags.Orientation }}
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{{ if and (ge $src.Width $size) (eq $orientation 8) }}
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{{ ($src.Resize (printf "%sx r90" $size)).Permalink }} {{ (printf "%sw" $size) }},
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{{ else if ge $src.Width $size }}{{ ($src.Resize (printf "%sx" $size)).Permalink }} {{ (printf "%sw" $size) }},{{ end }}
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{{ end }}
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{{ end }}'
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{{/* when no support for srcset (old browsers, RSS), we load small (800px) */}}
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{{/* if image smaller than 800, then load the image itself */}}
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{{ if ge $src.Width "800" }}src="{{ ($src.Resize "800x").Permalink }}"
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{{ else }}src="{{ $src.Permalink }}"
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{{ end }}
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{{ else }}
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{{/* fall back to stock hugo behaviour when image is not available in bundle */}}
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src="{{ .Get "src" }}"
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{{ end }}
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{{- if or (.Get "alt") (.Get "caption") }}
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alt="{{ with .Get "alt" }}{{ . }}{{ else }}{{ .Get "caption" | markdownify| plainify }}{{ end }}"
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{{- end -}}
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{{- with .Get "width" }} width="{{ . }}"{{ end -}}
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{{- with .Get "height" }} height="{{ . }}"{{ end -}}
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/> <!-- Closing img tag -->
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{{- if .Get "link" }}</a>{{ end -}}
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{{- if or (or (.Get "title") (.Get "caption")) (.Get "attr") -}}
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<figcaption>
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{{ with (.Get "title") -}}
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<h4>{{ . }}</h4>
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{{- end -}}
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{{- if or (.Get "caption") (.Get "attr") -}}<p>
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{{- .Get "caption" | markdownify -}}
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{{- with .Get "attrlink" }}
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<a href="{{ . }}">
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{{- end -}}
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{{- .Get "attr" | markdownify -}}
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{{- if .Get "attrlink" }}</a>{{ end }}</p>
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{{- end }}
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</figcaption>
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{{- end }}
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</figure>
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