Jekyll Responsive Images is a Jekyll plugin and utility for automatically resizing images. Its intended use is for sites which want to display responsive images using something like srcset
or Imager.js.
You can either use the gem and update your _config.yml
:
$ gem install jekyll-responsive_image
# _config.yml
gems: [jekyll-responsive_image]
Or you can simply copy responsive_image.rb
into your _plugins
directory.
An example configuration is below.
responsive_image:
# [Required]
# Path to the image template.
template: _includes/responsive-image.html
# [Optional, Default: 85]
# Quality to use when resizing images.
default_quality: 90
# [Optional, Default: []]
# An array of resize configuration objects. Each object must contain at least
# a `width` value.
sizes:
- width: 480 # [Required] How wide the resized image will be.
quality: 80 # [Optional] Overrides default_quality for this size.
- width: 800
- width: 1400
quality: 90
# [Optional, Default: assets/resized/%{filename}-%{width}x%{height}.%{extension}]
# The template used when generating filenames for resized images.
#
# Parameters available are:
# %{basename} Basename of the file (assets/some-file.jpg => some-file.jpg)
# %{filename} Basename without the extension (assets/some-file.jpg => some-file)
# %{extension} Extension of the file (assets/some-file.jpg => jpg)
# %{width} Width of the resized image
# %{height} Height of the resized image
#
output_path_format: assets/resized/%{width}/%{basename}
Replace your images with the responsive_image
tag, specifying the path to the image in the path
attribute.
{% responsive_image path: assets/my-file.jpg %}
You can override the template on a per-image basis by specifying the template
attribute.
{% responsive_image path: assets/my-file.jpg template: _includes/another-template.html %}
Any extra attributes will be passed straight to the template as variables.
{% responsive_image path: assets/image.jpg alt: "Lorem ipsum..." title: "Lorem ipsum..." %}
You can use Liquid variables as attributes with the responsive_image_block
tag. This tag works in exactly the same way as the responsive_image
tag, but is implemented as a block tag to allow for more complex logic.
Important! The attributes in the
responsive_image_block
tag are parsed as YAML, so whitespace and indentation are important!
{% assign path = 'assets/test.png' %}
{% assign alt = 'Lorem ipsum...' %}
{% responsive_image_block %}
path: {{ path }}
alt: {{ alt }}
{% if title %}
title: {{ title }}
{% endif %}
{% endresponsive_image_block %}
You will need to create a template in order to use the responsive_image
tag. Below are some sample templates to get you started.
{% capture srcset %}
{% for i in resized %}
/{{ i.path }} {{ i.width }}w,
{% endfor %}
{% endcapture %}
<img src="/{{ path }}" srcset="{{ srcset | strip_newlines }} /{{ original.path }} {{ original.width }}w">
<picture>
{% for i in resized %}
<source media="(min-width: {{ i.width }}px)" srcset="/{{ i.path }}">
{% endfor %}
<img src="/{{ path }}">
</picture>
Responsive images using Imager.js
This template assumes an
output_path_format
ofassets/resized/%{width}/%{basename}
{% assign smallest = resized | sort: 'width' | first %}
<div class="responsive-image">
<img class="responsive-image__placeholder" src="/{{ smallest.path }}">
<div class="responsive-image__delayed" data-src="/assets/resized/{width}/{{ original.basename }}"></div>
</div>
<script>
new Imager('.responsive-image__delayed', {
availableWidths: [{{ resized | map: 'width' | join: ', ' }}]
onImagesReplaced: function() {
$('.responsive-image__placeholder').hide();
}
});
</script>
The following variables are available in the template:
Variable | Type | Description |
---|---|---|
path |
String | The path of the unmodified image. This is always the same as the path attribute passed to the tag. |
resized |
Array | An array of all the resized images. Each image is an Image Object. |
original |
Object | An Image Object containing information about the original image. |
* |
String | Any other attributes will be passed to the template verbatim as strings. |
Image objects (like original
and each object in resized
) contain the following properties:
Variable | Type | Description |
---|---|---|
path |
String | The path to the image. |
width |
Integer | The width of the image. |
height |
Integer | The height of the image. |
basename |
String | Basename of the file (assets/some-file.jpg => some-file.jpg ). |
filename |
String | Basename without the extension (assets/some-file.jpg => some-file ). |
extension |
String | Extension of the file (assets/some-file.jpg => jpg ). |