Refactor seo.html and support OpenGraph image overrides (#1321)

- Refactor seo.html include and add `page.header.og_image` override
- DRY up handling of page images (`page.header.image`, `page.header.overlay_image`, `page.header.teaser`, and `site.og_image`).
- Allow page images to be set with `header.og_image` page variable in YAML Front Matter as per feature request in #1316.
- Add sample posts for testing `og_image` override
- Set author bio as site OpenGraph default image
- Document `page.header.og_image` OpenGraph override
- Update CHANGELOG and history

Close #1316

CHANGELOG.md

@@ -12,6 +12,8 @@
 - Add support for Staticman v2 endpoint and reCAPTCHA.
 - Add Polish localized UI text strings. [#1304](https://github.com/mmistakes/minimal-mistakes/pull/1304)
 - Add toggleable table of contents via YAML Front Matter. Note: `toc` helper include will be deprecated in next major version. [#1222](https://github.com/mmistakes/minimal-mistakes/issues/1222)
+- Refactor seo.html include to DRY-up page image handling.
+- Add support for setting what image is used by OpenGraph and Twitter via `page.header.og_image`. [#1316](https://github.com/mmistakes/minimal-mistakes/issues/1316)
 
 ### Bug Fixes
 

_includes/seo.html

@@ -54,21 +54,37 @@
   <meta property="og:description" content="{{ seo_description }}">
 {% endif %}
 
+{% assign page_large_image = page.header.og_image | default: page.header.overlay_image | default: page.header.image %}
+{% unless page_large_image contains '://' %}
+  {% assign page_large_image = page_large_image | absolute_url %}
+{% endunless %}
+{% assign page_large_image = page_large_image | escape %}
+
+{% assign page_teaser_image = page.header.teaser | default: site.og_image %}
+{% unless page_teaser_image contains '://' %}
+  {% assign page_teaser_image = page_teaser_image | absolute_url %}
+{% endunless %}
+{% assign page_teaser_image = page_teaser_image | escape %}
+
+{% assign site_og_image = site.og_image %}
+{% unless site_og_image contains '://' %}
+  {% assign site_og_image = site_og_image | absolute_url %}
+{% endunless %}
+{% assign site_og_image = site_og_image | escape %}
+
 {% if site.twitter.username %}
   <meta name="twitter:site" content="@{{ site.twitter.username | replace: "@", "" }}">
   <meta name="twitter:title" content="{{ page.title | default: site.title | markdownify | strip_html | strip_newlines | escape_once }}">
   <meta name="twitter:description" content="{{ seo_description }}">
   <meta name="twitter:url" content="{{ canonical_url }}">
 
-  {% if page.header.image %}
+  {% if page_large_image %}
     <meta name="twitter:card" content="summary_large_image">
-    <meta name="twitter:image" content="{% if page.header.image contains "://" %}{{ page.header.image }}{% else %}{{ page.header.image | absolute_url }}{% endif %}">
+    <meta name="twitter:image" content="{{ page_large_image }}">
   {% else %}
     <meta name="twitter:card" content="summary">
-    {% if page.header.teaser %}
+    {% if page_teaser_image %}
-      <meta name="twitter:image" content="{% if page.header.teaser contains "://" %}{{ page.header.teaser }}{% else %}{{ page.header.teaser | absolute_url }}{% endif %}">
+      <meta name="twitter:image" content="{{ page_teaser_image }}">
-    {% elsif site.og_image %}
-      <meta name="twitter:image" content="{{ site.og_image | absolute_url }}">
     {% endif %}
   {% endif %}
 
@@ -87,14 +103,10 @@
   {% endif %}
 {% endif %}
 
-{% if page.header.image %}
+{% if page_large_image %}
-  <meta property="og:image" content="{% if page.header.image contains "://" %}{{ page.header.image }}{% else %}{{ page.header.image | absolute_url }}{% endif %}">
+  <meta property="og:image" content="{{ page_large_image }}">
-{% elsif page.header.overlay_image %}
+{% elsif page_teaser_image %}
-  <meta property="og:image" content="{% if page.header.overlay_image contains "://" %}{{ page.header.overlay_image }}{% else %}{{ page.header.overlay_image | absolute_url }}{% endif %}">
+  <meta property="og:image" content="{{ page_teaser_image }}">
-{% elsif page.header.teaser %}
-  <meta property="og:image" content="{% if page.header.teaser contains "://" %}{{ page.header.teaser }}{% else %}{{ page.header.teaser | absolute_url }}{% endif %}">
-{% elsif site.og_image %}
-  <meta property="og:image" content="{% if site.og_image contains "://" %}{{ site.og_image }}{% else %}{{ site.og_image | absolute_url }}{% endif %}">
 {% endif %}
 
 {% if page.date %}
@@ -115,7 +127,7 @@
       "@context": "http://schema.org",
       "@type": "Organization",
       "url": {{ seo_url | jsonify }},
-      "logo": {{ site.og_image | absolute_url | jsonify }}
+      "logo": {{ site_og_image | jsonify }}
     }
   </script>
 {% endif %}

docs/_docs/10-layouts.md

@@ -7,7 +7,7 @@ single_layout_gallery:
     alt: "single layout with header example"
   - image_path: /assets/images/mm-layout-single-meta.png
     alt: "single layout with comments and related posts"
-last_modified_at: 2017-10-20T14:26:10-04:00
+last_modified_at: 2017-10-26T15:42:42-04:00
 toc: true
 toc_label: "Included Layouts"
 toc_icon: "columns"
@@ -380,6 +380,19 @@ header:
   cta_url: "https://unsplash.com"
 ```
 
+### OpenGraph & Twitter Card Images
+
+By default the large page header or overlay images are used for sharing previews. If you'd like to set this image to something else use `page.header.og_image` like:
+
+```yaml
+header:
+  image: /assets/images/your-page-image.jpg
+  og_image: /assets/images/your-og-image.jpg
+```
+
+**ProTip:** `og_image` is useful for setting OpenGraph images on pages that don't have a header or overlay image.
+{: .notice--info}
+
 ---
 
 ## Sidebars

docs/_docs/18-history.md

@@ -4,7 +4,7 @@ permalink: /docs/history/
 excerpt: "Change log of enhancements and bug fixes made to the theme."
 sidebar:
   nav: docs
-last_modified_at: 2017-10-20T15:56:30-04:00
+last_modified_at: 2017-10-26T15:33:41-04:00
 toc: true
 ---
 
@@ -22,6 +22,8 @@ toc: true
 - Add support for Staticman v2 endpoint and reCAPTCHA.
 - Add Polish localized UI text strings. [#1304](https://github.com/mmistakes/minimal-mistakes/pull/1304)
 - Add toggleable table of contents via YAML Front Matter. Note: `toc` helper include will be deprecated in next major version. [#1222](https://github.com/mmistakes/minimal-mistakes/issues/1222)
+- Refactor seo.html include to DRY-up page image handling.
+- Add support for setting what image is used by OpenGraph and Twitter via `page.header.og_image`. [#1316](https://github.com/mmistakes/minimal-mistakes/issues/1316)
 
 ### Bug Fixes
 

docs/_includes/seo.html

@@ -54,21 +54,37 @@
   <meta property="og:description" content="{{ seo_description }}">
 {% endif %}
 
+{% assign page_large_image = page.header.og_image | default: page.header.overlay_image | default: page.header.image %}
+{% unless page_large_image contains '://' %}
+  {% assign page_large_image = page_large_image | absolute_url %}
+{% endunless %}
+{% assign page_large_image = page_large_image | escape %}
+
+{% assign page_teaser_image = page.header.teaser | default: site.og_image %}
+{% unless page_teaser_image contains '://' %}
+  {% assign page_teaser_image = page_teaser_image | absolute_url %}
+{% endunless %}
+{% assign page_teaser_image = page_teaser_image | escape %}
+
+{% assign site_og_image = site.og_image %}
+{% unless site_og_image contains '://' %}
+  {% assign site_og_image = site_og_image | absolute_url %}
+{% endunless %}
+{% assign site_og_image = site_og_image | escape %}
+
 {% if site.twitter.username %}
   <meta name="twitter:site" content="@{{ site.twitter.username | replace: "@", "" }}">
   <meta name="twitter:title" content="{{ page.title | default: site.title | markdownify | strip_html | strip_newlines | escape_once }}">
   <meta name="twitter:description" content="{{ seo_description }}">
   <meta name="twitter:url" content="{{ canonical_url }}">
 
-{% if page.header.image %}
+  {% if page_large_image %}
     <meta name="twitter:card" content="summary_large_image">
-  <meta name="twitter:image" content="{% if page.header.image contains "://" %}{{ page.header.image }}{% else %}{{ page.header.image | absolute_url }}{% endif %}">
+    <meta name="twitter:image" content="{{ page_large_image }}">
   {% else %}
     <meta name="twitter:card" content="summary">
-  {% if page.header.teaser %}
+    {% if page_teaser_image %}
-    <meta name="twitter:image" content="{% if page.header.teaser contains "://" %}{{ page.header.teaser }}{% else %}{{ page.header.teaser | absolute_url }}{% endif %}">
+      <meta name="twitter:image" content="{{ page_teaser_image }}">
-  {% elsif site.og_image %}
-    <meta name="twitter:image" content="{{ site.og_image | absolute_url }}">
     {% endif %}
   {% endif %}
 
@@ -87,14 +103,10 @@
   {% endif %}
 {% endif %}
 
-{% if page.header.image %}
+{% if page_large_image %}
-<meta property="og:image" content="{% if page.header.image contains "://" %}{{ page.header.image }}{% else %}{{ page.header.image | absolute_url }}{% endif %}">
+  <meta property="og:image" content="{{ page_large_image }}">
-{% elsif page.header.overlay_image %}
+{% elsif page_teaser_image %}
-<meta property="og:image" content="{% if page.header.overlay_image contains "://" %}{{ page.header.overlay_image }}{% else %}{{ page.header.overlay_image | absolute_url }}{% endif %}">
+  <meta property="og:image" content="{{ page_teaser_image }}">
-{% elsif page.header.teaser %}
-<meta property="og:image" content="{% if page.header.teaser contains "://" %}{{ page.header.teaser }}{% else %}{{ page.header.teaser | absolute_url }}{% endif %}">
-{% elsif site.og_image %}
-<meta property="og:image" content="{% if site.og_image contains "://" %}{{ site.og_image }}{% else %}{{ site.og_image | absolute_url }}{% endif %}">
 {% endif %}
 
 {% if page.date %}
@@ -115,7 +127,7 @@
       "@context": "http://schema.org",
       "@type": "Organization",
       "url": {{ seo_url | jsonify }},
-    "logo": {{ site.og_image | absolute_url | jsonify }}
+      "logo": {{ site_og_image | jsonify }}
     }
   </script>
 {% endif %}

docs/_posts/2010-08-05-post-header-image-og-override.md

@@ -0,0 +1,22 @@
+---
+title: "Post: Header Image with OpenGraph Override"
+header:
+  image: /assets/images/page-header-image.png
+  og_image: /assets/images/page-header-og-image.png
+categories:
+  - Layout
+  - Uncategorized
+tags:
+  - edge case
+  - image
+  - layout
+last_modified_at: 2017-10-26T15:12:19-04:00
+---
+
+This post has a header image with an OpenGraph override.
+
+```yaml
+header:
+  image: /assets/images/page-header-image.png
+  og_image: /assets/images/page-header-og-image.png
+```

docs/_posts/2010-08-05-post-header-overlay-image-og-override.md

@@ -0,0 +1,26 @@
+---
+title: "Post: Overlay Image with OpenGraph Override"
+header:
+  overlay_image: /assets/images/unsplash-image-1.jpg
+  og_image: /assets/images/page-header-og-image.png
+  caption: "Photo credit: [**Unsplash**](https://unsplash.com)"
+  cta_url: "https://unsplash.com"
+categories:
+  - Layout
+  - Uncategorized
+tags:
+  - edge case
+  - image
+  - layout
+last_modified_at: 2017-10-26T15:12:19-04:00
+---
+
+This post has a header image with an OpenGraph override.
+
+```yaml
+header:
+  overlay_image: /assets/images/unsplash-image-1.jpg
+  og_image: /assets/images/page-header-og-image.png
+  caption: "Photo credit: [**Unsplash**](https://unsplash.com)"
+  cta_url: "https://unsplash.com"
+```

docs/_posts/2010-08-05-post-teaser-image-og-override.md

@@ -0,0 +1,22 @@
+---
+title: "Post: Teaser Image with OpenGraph Override"
+header:
+  teaser: /assets/images/page-header-teaser.png
+  og_image: /assets/images/page-header-og-image.png
+categories:
+  - Layout
+  - Uncategorized
+tags:
+  - edge case
+  - image
+  - layout
+last_modified_at: 2017-10-26T15:12:19-04:00
+---
+
+This post has a teaser image with an OpenGraph override.
+
+```yaml
+header:
+  teaser: /assets/images/page-header-teaser.png
+  og_image: /assets/images/page-header-og-image.png
+```

test/_config.yml

@@ -63,7 +63,7 @@ facebook:
   username               :
   app_id                 :
   publisher              :
-og_image                 : # Open Graph/Twitter default site image
+og_image                 : "/assets/images/bio-photo.jpg"
 # For specifying social profiles
 # - https://developers.google.com/structured-data/customize/social-profiles
 social:

test/_posts/2010-08-05-post-header-image-og-override.md

@@ -0,0 +1,22 @@
+---
+title: "Post: Header Image with OpenGraph Override"
+header:
+  image: /assets/images/page-header-image.png
+  og_image: /assets/images/page-header-og-image.png
+categories:
+  - Layout
+  - Uncategorized
+tags:
+  - edge case
+  - image
+  - layout
+last_modified_at: 2017-10-26T15:12:19-04:00
+---
+
+This post has a header image with an OpenGraph override.
+
+```yaml
+header:
+  image: /assets/images/page-header-image.png
+  og_image: /assets/images/page-header-og-image.png
+```

test/_posts/2010-08-05-post-header-overlay-image-og-override.md

@@ -0,0 +1,26 @@
+---
+title: "Post: Overlay Image with OpenGraph Override"
+header:
+  overlay_image: /assets/images/unsplash-image-1.jpg
+  og_image: /assets/images/page-header-og-image.png
+  caption: "Photo credit: [**Unsplash**](https://unsplash.com)"
+  cta_url: "https://unsplash.com"
+categories:
+  - Layout
+  - Uncategorized
+tags:
+  - edge case
+  - image
+  - layout
+last_modified_at: 2017-10-26T15:12:19-04:00
+---
+
+This post has a header image with an OpenGraph override.
+
+```yaml
+header:
+  overlay_image: /assets/images/unsplash-image-1.jpg
+  og_image: /assets/images/page-header-og-image.png
+  caption: "Photo credit: [**Unsplash**](https://unsplash.com)"
+  cta_url: "https://unsplash.com"
+```

test/_posts/2010-08-05-post-teaser-image-og-override.md

@@ -0,0 +1,22 @@
+---
+title: "Post: Teaser Image with OpenGraph Override"
+header:
+  teaser: /assets/images/page-header-teaser.png
+  og_image: /assets/images/page-header-og-image.png
+categories:
+  - Layout
+  - Uncategorized
+tags:
+  - edge case
+  - image
+  - layout
+last_modified_at: 2017-10-26T15:12:19-04:00
+---
+
+This post has a teaser image with an OpenGraph override.
+
+```yaml
+header:
+  teaser: /assets/images/page-header-teaser.png
+  og_image: /assets/images/page-header-og-image.png
+```