pelican-plugins/liquid_tags

Liquid-style Tags

Author: Jake Vanderplas jakevdp@cs.washington.edu

This plugin allows liquid-style tags to be inserted into Markdown within Pelican documents via tags bounded by {% ... %}, a convention also used to extend Markdown in other publishing platforms such as Octopress.

This set of extensions does not actually interface with liquid, but allows users to define their own liquid-style tags which will be inserted into the Markdown preprocessor stream. There are several built-in tags, which can be added as follows.

First, in your pelicanconf.py file, add the plugins you want to use:

PLUGIN_PATH = '/path/to/pelican-plugins'
PLUGINS = ['liquid_tags.img', 'liquid_tags.video',
           'liquid_tags.youtube', 'liquid_tags.vimeo',
           'liquid_tags.include_code', 'liquid_tags.notebook']

Following below is more information about these and other tags.

Image Tag

To insert a sized and labeled image in your document, enable the liquid_tags.img plugin and use the following:

{% img [class name(s)] path/to/image [width [height]] [title text | "title text" ["alt text"]] %}

Base64 Image (inline image) tag

b64img is based on theimg tag, but instead of inserting a link to the image it encodes it as base64 text and inserts it into a<img src= attribute.

To use it:

1. Enable liquid_tags.b64img
2. Insert a tag as follows: {% b64img [class name(s)] path/to/image [width [height]] [title text | "title text" ["alt text"]] %}

Images are encoded at generation time, so you can use any local path (just be sure that the image will remain in the same location for subsequent site generations).

Instagram Tag

To insert a sized and labeled Instagram image in your document by its shortcode (such as pFI0CAIZna), enable the liquid_tags.gram plugin and use the following:

{% gram shortcode [size] [width] [class name(s)] [title text | "title text" ["alt text"]] %}

You can specify a size with t, m, or l.

Flickr Tag

To insert a Flickr image to a post, follow these steps:

1. Enable liquid_tags.flickr
2. Get an API key from Flickr
3. Add FLICKR_API_KEY to your settings file

4. Add this to your source document:

   {% flickr image_id [small|medium|large] ["alt text"|'alt text'] %}

Giphy Tag

To insert a GIF from Giphy in your document by its ID (such as aMSJFS6oFX0fC), enable the liquid_tags.giphy plugin and use the following:

{% giphy gif_id ["alt text"|'alt text'] %}

Important: You must request a production API key from Giphy. If you just want to try it out, you can use the public beta key contained within the GiphyAPI README file.

Soundcloud Tag

To insert a Soundcloud widget in your content, follow these steps:

1. Enable liquid_tags.soundcloud

2. Add this to your source document:

   {% soundcloud track_url %}

YouTube Tag

To insert a YouTube video into your content, enable the liquid_tags.youtube plugin and add the following to your source document:

{% youtube youtube_id [width] [height] %}

The width and height are in pixels and are optional. If they are not specified, then the dimensions will be 640 (wide) by 390 (tall).

If you experience issues with code generation (e.g., missing closing tags), add SUMMARY_MAX_LENGTH = None to your settings file.

Vimeo Tag

To insert a Vimeo video into your content, enable the liquid_tags.vimeo plugin and add the following to your source document:

{% vimeo vimeo_id [width] [height] %}

The width and height are in pixels and are optional. If they are not specified, then the dimensions will be 640 (wide) by 390 (tall).

If you experience issues with code generation (e.g., missing closing tags), add SUMMARY_MAX_LENGTH = None to your settings file.

Speakerdeck Tag

To insert a Speakerdeck viewer into your content, enable the liquid_tags.speakerdeck plugin and add the following to your source document:

{% speakerdeck speakerdeck_id %}

Video Tag

To insert HTML5-friendly video into your content, enable the liquid_tags.video plugin and add the following to your source document:

{% video /url/to/video.mp4 [width] [height] [/path/to/poster.png] %}

The width and height are in pixels and are optional. If they are not specified, then the native video size will be used. The poster image is a preview image that is shown prior to initiating video playback.

To link to a video file, make sure it is in a static directory, transmitted to your server, and available at the specified URL.

Audio Tag

To insert HTML5 audio into a post, enable the liquid_tags.audio plugin and add the following to your source document:

{% audio url/to/audio [url/to/audio] [url/to/audio] %}

This tag supports up to three audio URL arguments so you can add different audio file versions, as different browsers support different file formats.

To link to a audio file, make sure it is in a static directory, transmitted to your server, and available at the specified URL.

Include Code

To include code from a file in your document with a link to the original file, enable the liquid_tags.include_code plugin, and add the following to your source document:

{% include_code /path/to/code.py [lang:python] [lines:X-Y] [:hidefilename:] [title] %}

All arguments are optional but must be specified in the order shown above. If using :hidefilename:, a title must be provided as indicated above.

{% include_code /path/to/code.py lines:1-10 :hidefilename: Test Example %}

This example will show the first ten lines of the file while hiding the actual filename.

The script must be in the code subdirectory of your content folder; the default location can be changed by specifying the directory in your settings file thusly:

CODE_DIR = 'code'

Additionally, in order for the resulting hyperlink to work, this directory must be listed in the STATIC_PATHS setting. For example:

STATIC_PATHS = ['images', 'code']

IPython notebooks

To insert an IPython notebook into your post, enable the liquid_tags.notebook plugin and add the following to your source document:

{% notebook filename.ipynb %}

The file should be specified relative to the notebooks subdirectory of the content directory. Optionally, this subdirectory can be specified in your settings file:

NOTEBOOK_DIR = 'notebooks'

Because the conversion and rendering of notebooks is rather involved, there are a few extra steps required for this plugin. First, you must install IPython:

  pip install ipython==2.4.1

After running Pelican on content containing an IPython notebook tag, a file called _nb_header.html will be generated in the main directory. The content of this file should be included in the header of your theme. An easy way to accomplish this is to add the following to your theme’s header template…

  {% if EXTRA_HEADER %}
  {{ EXTRA_HEADER }}
  {% endif %}

… and in your settings file, include the line:

  EXTRA_HEADER = open('_nb_header.html').read().decode('utf-8')

This will insert the proper CSS formatting into your generated document.

Optional Arguments for Notebook Tags

The notebook tag also has two optional arguments: cells and language.

• You can specify a slice of cells to include:

{% notebook filename.ipynb cells[2:8] %}

• You can also specify the name of the language that Pygments should use for highlighting code cells. For a list of the language short names that Pygments can highlight, refer to the Pygments lexer list.

{% notebook filename.ipynb language[julia] %}

This may be helpful for those using IJulia or notebooks in other languages, especially as the IPython project broadens its scope to support other languages. The default language for highlighting is ipython.

• These options can be used separately, together, or not at all. However, if both tags are used then cells must come before language:

{% notebook filename.ipynb cells[2:8] language[julia] %}

Collapsible Code in IPython Notebooks

The IPython plugin also enables collapsible code input boxes. For this to work you must first copy the file pelicanhtml_3.tpl (for IPython 3.x) or pelicanhtml_2.tpl (for IPython 2.x) to the top level of your content directory. Notebook input cells containing the comment line # <!-- collapse=True --> will be collapsed when the HTML page is loaded and can be expanded by tapping on them. Cells containing the comment line # <!-- collapse=False --> will be expanded on load but can be collapsed by tapping on their header. Cells without collapsed comments are rendered as standard code input cells.

Configuration settings in custom tags

Tags do not have access to the full Pelicans settings, and instead arrange for the variables to be passed to the tag. For tag authors who plan to add their tag as in-tree tags, they can just add the variables they need to an array in mdx_liquid_tags.py, but out-of-tree tags can specify which variables they need by including a tuple of (variable, default value, helptext) in the user's pelicanconf.py settings:

LIQUID_CONFIGS = (('PATH', '.', "The default path"), ('SITENAME', 'Default Sitename', 'The name of the site'))

Testing

To test the plugin in multiple environments we use tox. To run the entire test suite:

cd path/to/liquid_tags
tox