Add blogPhoto shortcode

This shortcode is intended to be used in blogposts to include photos. It
downscales them and uses srcset to serve appropriate sizes to the
browsers.

themes/patek/layouts/shortcodes/blogPhoto.html

@@ -0,0 +1,29 @@
+{{- /*
+Usage:
+
+{{< blogPhoto "filename_relative_to_page.ext" "Alt text" >}}
+
+or
+
+{{< blogPhoto src="filename_relative_to_page.ext" alt="Alt text" >}}
+
+*/ -}}
+{{- $imageName := false -}}
+{{- $alt := false -}}
+{{- if .IsNamedParams -}}
+    {{- $imageName = .Get "src" | default nil -}}
+    {{- $alt = .Get "alt" | default nil -}}
+{{- else -}}
+    {{- $imageName = .Get 0 -}}
+    {{- $alt = .Get 1 -}}
+{{- end -}}
+{{- if (eq $imageName nil) }}{{ errorf "Missing image name in %s" .Position }}{{ end -}}
+{{- if (eq $alt nil) }}{{ errorf "Missing alt for image %s in %s" $imageName .Position }}{{ end -}}
+
+{{- $img := .Page.Resources.GetMatch (printf "%s" $imageName) | default nil -}}
+{{- if (eq $img nil) }}{{ errorf "Image %s not found in %s" $imageName .Position }}{{ end -}}
+{{- $resizedFullHD := $img.Fit "1920x1080 q50" -}}
+{{- $resizedHD := $img.Fit "1280x720 q50" -}}
+{{- $resizedSD := $img.Fit "640x360 q50" -}}
+
+<img src="{{ $resizedFullHD.RelPermalink }}" alt="{{ $alt }}" srcset="{{ $resizedFullHD.RelPermalink }} 1080w, {{ $resizedHD.RelPermalink }} 720w, {{ $resizedSD.RelPermalink }} 360w" sizes="(orientation: portrait) 100vw, 50vw">