Generate thumbnail versions of your jpeg & png images

If you bundle update, you will probably get the following error:

/middleman-core-3.2.2/lib/middleman-core/configuration.rb:37:in \`method_missing': 
undefined method \`before_build' for Middleman::Application::MiddlemanApplication1:Class (NoMethodError)

middleman-thumbnailer will only (currently) work with the latest v3-stable branch of middleman from git. In your Gemfile use this (for now):

gem 'middleman', :git => 'https://github.com/middleman/middleman.git', branch: 'v3-stable'

Add this line to your Gemfile:

gem 'middleman-thumbnailer', :git => 'https://github.com/nhemsley/middleman-thumbnailer.git'

And something like this to your config.rb:

  require 'middleman-thumbnailer'
  activate :thumbnailer, 
    :dimensions => {
      :small => '200x',
      :medium => '400x300'
    },
    :include_data_thumbnails => true,
    :namespace_directory => %w(gallery)

If you have a file in images called (for example) background.png, thumbnail versions will be created called: background-small-200x.png background-medium-400x300.png

:include_data_thumbnails the list of images will be included in the data-thumbnails attribute for each image displayed with the thumbnail helper

:namespace_directory only thumbnail images found within this directory (within the images directory of course)

##Helpers

thumbnail(image, size, [html_options]) will return the thumbnail image tag for the image of the named dimension/size

thumbnail_url(image, size) will return the url for the image of the named dimension/size