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September 5, 2019 17:23
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Hugo partial for generating <picture> with responsive image
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{{/* Adapted from https://gist.github.com/randallmlough/98c9c949b25f2a41259029e03dd037f3 */}} | |
{{- $image := replaceRE "^https?://[^/]+/(.*)" "$1" ($.Scratch.Get "image") -}} | |
{{- $media := (.Site.GetPage "page" "media").Resources -}} | |
{{- $original := index ($media.Match (printf "%s" $image)) 0 -}} | |
{{- $width := $original.Width -}} | |
{{- $intWidth := int $width -}} | |
{{- $sizes := $.Param "sizes" -}} | |
{{- $options := $.Param "options" -}} | |
{{- $usePicture := false -}}{{/* true: Use picture element with source definitions */}} | |
{{- $multipleSizes := true -}}{{/* true: Provide multiple img sizes attribute */}} | |
{{- $debug := false -}} | |
{{- if $debug -}} | |
<div id="can-delete"> | |
<table> | |
<thead> | |
<tr><td>Variable</td><td>Value</td></tr> | |
</thead> | |
<tbody> | |
<tr><td>Image</td><td>{{ $image }}</td></tr> | |
<tr><td>Media</td><td>{{ $media }}</td></tr> | |
<tr><td>Original Image Path</td><td>{{ $original.RelPermalink }}</td></tr> | |
<tr><td>Original Width</td><td>{{$width}}</td></tr> | |
<tr><td>Sizes array</td><td>{{$sizes}}</td></tr> | |
<tr><td>Len sizes</td><td>{{ len $sizes}}</td></tr> | |
<tr><td>Options</td><td>{{ $options }}</td></tr> | |
</tbody> | |
</table> | |
</div> | |
{{- end -}} | |
{{- if $usePicture -}} | |
<picture> | |
<!--[if IE 9]><video style="display: none;"><![endif]--> | |
{{- end -}} | |
{{- $.Scratch.Set "srcPath" ($original.RelPermalink) }} | |
{{- range $i, $sort := (seq (len $sizes)) -}} | |
{{- if ge (index $sizes $i) 10 -}} | |
{{- $.Scratch.Add "sort" (slice (index $sizes $i)) -}} | |
{{- else -}} | |
{{- $floatSize := float (index $sizes $i) -}} | |
{{- $newSize := (math.Round (mul $intWidth $floatSize)) -}} | |
{{- $int2string := string $newSize -}} | |
{{- $.Scratch.Add "sort" (slice $int2string) -}} | |
{{- end -}} | |
{{- end -}} | |
{{- $sort := (sort (.Scratch.Get "sort") "value" "asc" ) -}} | |
{{- range $i, $num := (seq (len $sort )) -}} | |
{{- $imgSize := index $sort $i -}} | |
{{- $img := ($original.Resize (printf "%dx %s" $imgSize $options)) -}} | |
{{- $.Scratch.Add "sizes" (slice $img.Width) -}} | |
{{- $.Scratch.Set "srcPath" $img.RelPermalink }} | |
{{- $int2string := string $img.Width -}} | |
{{- $.Scratch.Add "srcsetdef" (slice (printf "%s %sw" $img.RelPermalink $int2string)) -}} | |
{{ $srcset := (printf "%s " $img.RelPermalink) -}} | |
{{- if $usePicture -}} | |
{{/* pretty sure this is wrong / incomplete - see responsive breakpoints tag generator */}} | |
<source srcset="{{ $srcset -}} 1x" media="(min-width: {{ index $sort $i }}px)"> | |
{{- end -}} | |
{{ end -}} | |
<img | |
{{ $viewWidth := 30 -}} | |
srcset="{{delimit (.Scratch.Get "srcsetdef") ",\n " }}" | |
{{ if $multipleSizes -}} | |
sizes="{{- $last := sub (len $sizes) 1 -}} | |
{{- range $sz := $sizes -}} | |
{{- printf "(max-width: %dpx) %dvw,\n " $sz $viewWidth -}} | |
{{ end }} | |
{{- printf "%dpx" (index (last 2 $sizes) 0) -}} " {{/* next to last seems arbitrary */}} | |
{{ else }} | |
sizes="{{- $sz := index $sizes 0 -}} | |
{{- printf "(max-width: %dpx) %dvw" $sz $viewWidth -}}" | |
{{ end -}} | |
src="{{- $.Scratch.Get "srcPath" -}}" > | |
{{- if $usePicture -}} | |
</picture> | |
{{- end -}} |
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