jekyll plugin that makes available the first image of a post in the template
Ruby
Latest commit 3125b1d Nov 10, 2016 1 @merlos - fixes #7 in jekyll 3.3.0

README.md

jekyll-auto-image plugin

jekyll plugin that makes available the first image of a post in the template as a variable.

By installing the plugin you will be able to access the first image of a page through {{ @page.image }}.

This plugin is useful if you want to:

  • Include an image on your list of posts
  • Set a twitter card image for a post (see example below)

Install

Add to your Gemfile:

gem 'jekyll-auto-image'

or run

$ gem install jekyll-auto-image

Then, add to your _config.yml:

gems:
  - jekyll-auto-image

The plugin allows you to set a default image for all pages/posts. To do that, add to your _config.yml:

 # _config.yml

 image: /path/to/your/default/image.png

Jekyll 3.0

Versions of jekyll-auto-image >= 1.1.0 are compatible with jekyll 3.0. If you require compatibility with jekyll 2.0 use jekyll-auto-image 1.0.2.

  # Run this command check installed versions
  $ gem list | grep jekyll
  jekyll (3.0.1)
  jekyll-auto-image (1.0.2)

Usage

In each post/page, the plugin will set {{ page.image }} following this fallback rules:

  1. Front matter image value
  2. First image in the post/page contents
  3. Default site image (defined in _config.yml)
  4. nil

Basically, the plugin will return the front matter image value if set. If it is not set, then it will look for the first image asset that is defined in your post content. If the post does not have any image, then it will set the site.image defined in _config.yml.

Example of usage

Example post 1:

---
layout: post
title: Post 1
---

This is my example post. It includes an image in the contents.

![first image](/assets/first_image.png)

Example post 2:

---
layout: post
title: Post 2
image: /assets/front_matter_image.png
---

This is my second example post, because the
post includes the front matter image, the plugin 
will return it instead of the first image in the 
contents.

![first image](/assets/first_image.png)

Template example

{% for post in site.posts %}
title: {{ post.title }}
<br>
image: {{ post.image }}
<hr>

Output HTML Rendered:

title: Post 1
<br>
image: /assets/first_image.png
<hr>

title: Post 2
<br>
image: /assets/front_matter_image.png

Example using twitter cards

Another use of this plugin is to create a twitter card.

You can define a set of <meta> elements in your head.html template, so when sharing a post in twitter, the tweet displays it in cool way. You have more info in twitter's developers page

Here you have a sample:

 <!-- twitter card -->
  <meta name="twitter:card" content="{% if page.image %}summary_large_image{% else %}summary{% endif %}">
  <meta name="twitter:site" content="@{{ site.twitter_username }}">
  <meta name="twitter:creator" content="@{{ site.twitter_username }}">
  <meta name="twitter:title" content="{% if page.title %}{{ page.title }}{% else %}{{ site.title }}{% endif %}">
  <meta name="twitter:description" content="{% if page.excerpt %}{{ page.excerpt | strip_html | strip_newlines | truncate: 200 }}{% else %}{{ site.description }}{% endif %}">
{% if page.image %}
  <meta name="twitter:image:src" content="{{ page.image | prepend: site.baseurl | prepend: site.url }}"> 
{% endif %} 
  <!-- end twitter card -->

You can validate how it will look using the cards validator

Contributing

  1. Fork it (https://github.com/merlos/jekyll-auto-image/fork)
  2. Create your feature branch (`git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request

Run tests

   $ rake test

The tests are based on the code of https://github.com/ivantsepp/jekyll-autolink_email

License

Copyright (c) 2015 Juan M. Merlos (@merlos) www.merlos.org Distributed under MIT License