48 lines
2 KiB
HTML
48 lines
2 KiB
HTML
{{- /*
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Open Graph image for link previews. The theme's head/meta.html writes og:image only for the
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"image" param; without it, this uses the first image in the page, a Markdown image or a
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gallery-image shortcode, scaled down to at most 1200 pixels wide, with its alt text as
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og:image:alt.
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*/ -}}
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{{- if not ($.Param "image") -}}
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{{- /* Whichever comes first: a Markdown image or a gallery-image shortcode (src and alt in "…" or `…`). */ -}}
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{{- with findRESubmatch `!\[([^\]]*)\]\(\s*<?([^\s)>]+)|\{\{<\s*gallery-image\s([^}]*)>\}\}` .RawContent 1 -}}
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{{- $alt := index . 0 1 -}}
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{{- $dest := index . 0 2 -}}
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{{- with index . 0 3 -}}
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{{- $dest = "" -}}
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{{- $alt = "" -}}
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{{- with findRESubmatch "\\bsrc=(?:\"([^\"]*)\"|`([^`]*)`)" . 1 }}{{ $dest = or (index . 0 1) (index . 0 2) }}{{ end -}}
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{{- with findRESubmatch "\\balt=(?:\"([^\"]*)\"|`([^`]*)`)" . 1 }}{{ $alt = or (index . 0 1) (index . 0 2) }}{{ end -}}
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{{- end -}}
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{{- $url := "" -}}
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{{- $width := 0 -}}
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{{- $height := 0 -}}
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{{- $resource := false -}}
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{{- if findRE `^https?://` $dest -}}
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{{- $url = $dest -}}
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{{- else -}}
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{{- $resource = or ($.Resources.Get (strings.TrimPrefix "./" $dest)) (resources.Get $dest) -}}
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{{- end -}}
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{{- with $resource -}}
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{{- $image := . -}}
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{{- if and (eq .ResourceType "image") (ne .MediaType.SubType "svg") -}}
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{{- if gt .Width 1200 }}{{ $image = .Resize "1200x" }}{{ end -}}
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{{- $width = $image.Width -}}
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{{- $height = $image.Height -}}
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{{- end -}}
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{{- $url = $image.Permalink -}}
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{{- end -}}
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{{- with $url }}
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<meta property="og:image" content="{{ . }}">
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{{- with $width }}
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<meta property="og:image:width" content="{{ . }}">
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<meta property="og:image:height" content="{{ $height }}">
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{{- end }}
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{{- with $alt }}
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<meta property="og:image:alt" content="{{ . }}">
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{{- end }}
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<meta name="twitter:card" content="summary_large_image">
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{{- end -}}
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{{- end -}}
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{{- end -}}
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