Roots Image Pipeline

Roots image pipeline is an asset pipeline for images which optionally compresses using imagemin and/or generates multiple sizes for use in HTML <picture> elements.

Note: This project is in early development, and versioning is a little different. Read this for more details.

Installation

• make sure you are in your roots project directory

• npm install roots-image-pipeline --save

• modify your app.coffee file to include the extension, for example:

  image_pipeline = require('roots-image-pipeline')
  
  module.exports =
    extensions: [image_pipeline(files: "assets/img/**", out: 'img', compress: true)]

Usage in templates

The function image() is exposed to your roots views, allowing you to output images quickly and easily. At it's simplest, simply pass image() a path to an image relative to the output directory specified in the function.

//- views/simple-example.jade
div.image-wrapper
  != image('example/image.png')

  //- <img src="/img/example/image.png">

image() takes a number of options which determine how the image is resized and displayed.

Sizes

Passing an array of sizes, containing a media query as well as width and/or height will generate the different sized images at compile time, and render the correct path for each source in your template.

//- views/picture-example.jade
div.picture-wrapper
  != image('example/image.png', {sizes: [{media: '(min-width: 40em)', width: 1024}, {width: 700}, {media: 'fallback', width: 1024}]})

  //- <picture>
  //-   <source srcset="/img/example/image-1024w.png" media="(min-width: 40em)">
  //-   <source srcset="/img/example/image-700w.png">
  //-   <img src="/img/example/image-1024w.png">
  //- </picture>

@2X Images

Passing retina: true in the options object will also generate and add the sources for @2x assets.

//- views/picture-example.jade
div.picture-wrapper
  != image('example/image.png', {sizes: [{media: '(min-width: 40em)', width: 1024}, {width: 700}, {media: 'fallback', width: 1024}], retina: true})

  //- <picture>
  //-   <source srcset="/img/example/image-1024w.png 1x, /img/example/[email protected] 2x" media="(min-width: 40em)">
  //-   <source srcset="/img/example/image-700w.png 1x, /img/example/[email protected] 2x">
  //-   <img src="/img/example/image-1024w.png">
  //- </picture>

Options

files

String or array of strings (minimatch supported) pointing to one or more file paths to be built. Default is assets/img/**

manifest

A path, relative to the roots project's root, to a manifest file (explained above), which contains a list of strings (minimatch supported) pointing to one more more file paths to be built.

out

If provided, all image files will be output to this directory in your project's output. Default is img

compress

Compresses images. Default is true.

opts

Options to be passed into imagemin plugins. Only does anything useful when compress is true.

# Defaults
opts:
  jpegoptim:
    progressive: true
    max: 70
  pngquant:
    quality: '50-70'
    speed: 1
  gifsicle:
    interlaced: true
  svgo: {}
  webp:
    quality: 70
    alphaQuality: 50
    lossless: false

output_webp

When true, after an image is passed through the compressor, a new .webp image is created in the output directory, alongside the matching jpg/png. Default is false.

Caveat: Converting some large png images with high levels of transparency can occasionally leave you with a webp image far larger than the original png. Use with caution.

To conditionally server webp images to those browsers who can display them, add the following to your nginx configuration:

http {
  ...

  map $http_accept $webp_suffix {
    default "";
    "~*webp" ".webp";
  }

  ...
}

server {
  ...

  # Load webp images instead of jpg/png if browser headers indicate support and files exist
  location ~* ^(?P<basename>.+)\.(jpg|jpeg|png)$ {
    try_files $basename$webp_suffix $uri =404;
  }

  ...
}

Any option accepted by the various imagemin plugins can be passed through here.

License & Contributing

• Details on the license can be found here
• Details on running tests and contributing can be found here