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. Liquid uses tags bounded by {% ... %}, and is used to extend markdown in other blogging 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']

There are several options available

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

There is one more tag for image: b64img. It is based on img tag, but instead of inserting link on image it acutally reads image and inserts it as base64 text into <img src= attribute.

To use it:

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

Images are read on compilation phase so you can use any local path (just be sure that image will remain there on next compilation)

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.

Youtube Tag

To insert youtube video into a post, enable the liquid_tags.youtube plugin, and add to your document:

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

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

If you're experiencing issues with code generating (i.e. missing closing tags), add SUMMARY_MAX_LENGTH = None to your config.

Vimeo Tag

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

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

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

If you're experiencing issues with code generating (i.e. missing closing tags), add SUMMARY_MAX_LENGTH = None to your config.

Video Tag

To insert flash/HTML5-friendly video into a post, enable the liquid_tags.video plugin, and add to your document:

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

The width and height are in pixels, and can be optionally specified. If they are not, then the original video size will be used. The poster is an image which is used as a preview of the video.

To use a video from file, make sure it's in a static directory and put in the appropriate 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 to your document:

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

All arguments are optional but their order must be kept. :hidefilename: is only allowed if a title is also given.

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

This example will show the first 10 lines of the file while hiding the actual filename.

The script must be in the code subdirectory of your content folder: this default location can be changed by specifying

CODE_DIR = 'code'

within your configuration file. Additionally, in order for the resulting hyperlink to work, this directory must be listed under the STATIC_PATHS setting, e.g.:

STATIC_PATHS = ['images', 'code']

IPython notebooks

To insert an IPython notebook into your post, enable the liquid_tags.notebook plugin and add to your 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 the config 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 will need to install IPython:

  pip install ipython==2.4.1

• After typing "make html" when using the notebook tag, a file called _nb_header.html will be produced in the main directory. The content of the file should be included in the header of the theme. An easy way to accomplish this is to add the following lines within the header template of the theme you use:

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

and in your configuration file, include the line:

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

this will insert the proper css formatting into your 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 a language which Pygments should use for highlighting code cells. A list of the short names for languages that Pygments will highlight can be found here.

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

This may be helpful for those using IJulia or notebooks in any other language, especially as the IPython project broadens its scope of language compatibility. By default, the language for highlighting will be 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 plugin also enables collapsible code input boxes. For this to work you first need to copy the file pelicanhtml_3.tpl (for IPython 3.x, pelicanhtml_2.tpl (for IPython 2.x)...) to the top level of your Pelican blog. Notebook input cells containing the comment line # <!-- collapse=True --> will be collapsed when the html page is loaded and can be expanded by clicking on them. Cells containing the comment line # <!-- collapse=False --> will be open on load but can be collapsed by clicking on their header. Cells without collapse comments are rendered as standard code input cells.

Testing

To test the plugin in multiple environments we use tox, to run the entire test suite, just type:

cd path/to/liquid_tags
tox