Class: Jekyll::ImageOptimGenerator

Inherits:
Generator
  • Object
show all
Defined in:
lib/jekyll-image-optim.rb

Instance Method Summary collapse

Instance Method Details

#analyze(image) ⇒ Object

Determine whether or not optimization needs to occur.



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# File 'lib/jekyll-image-optim.rb', line 67

def analyze(image)
  if @last_update.has_key? image
    # If we've touched the image before, but it's been modified, optimize.
    optimize image if @last_update[image] != File.mtime(image)
  else
    # If the image is new, optimize.
    optimize image
  end
end

#archival_filename(image) ⇒ Object

Adds the date/time of archival as well as the MD5 digest of the original source file.



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# File 'lib/jekyll-image-optim.rb', line 89

def archival_filename(image)
  ext = File.extname(image)
  "%s/%s-%s-%s%s" % [
    @config["archive_dir"],
    File.basename(image, ext),
    DateTime.now.strftime("%Y-%m-%d-%H-%M-%S"),
    Digest::MD5.file(image).hexdigest,
    ext,
  ]
end

#default_options ⇒ Object

Native settings for the plugin. Override with corresonding entries to _config.yml under “image_optim”

Example:

[_config.yml]
image_optim:
  archive_dir: "_my_original_images"
  cache_file: "_custom_file.yml"
  image_glob: "webroot/images/*.png"



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# File 'lib/jekyll-image-optim.rb', line 54

def default_options
  {
    # Where do we store archival copies of the originals?
    "archive_dir" => "_image_optim_archive",
    # Where do we store our cache file?
    "cache_file" => "_image_optim_cache.yml",
    # What images do we search for?
    "image_glob" => "images/**/*.{gif,jpg,jpeg,png}",
  }
end

#generate(site) ⇒ Object

Entry point for the plugin.



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# File 'lib/jekyll-image-optim.rb', line 11

def generate(site)
  # Read configuration. Defaults first, then overrides from _config.yml.
  config = YAML::load_file "_config.yml"
  config = config["image_optim"] || {}
  @config = default_options.merge! config

  # Initialize the ImageOptim library, which does the heavy lifting.
  @image_optim = ImageOptim.new(
    {
      :allow_lossy => true,  #Allow worker, it is always lossy (defaults to false)
      :svgo => false,
      :pngout => false,
      :verbose => false,
      :pngquant => {:quality => 70..85},  #min..max - don't save below min, use less colors below max (both in range 0..100; in yaml - !ruby/range 0..100), ignored in default/lossless mode (defaults to 100..100, 0..100 in lossy mode)
      :jpegrecompress => {:quality => 0},   #JPEG quality preset: 0 - low, 1 - medium, 2 - high, 3 - veryhigh (defaults to 3)
      :jpegoptim => {:max_quality => 85}
    })

  # Read the cache file, if it exists.
  @last_update = YAML::load_file @config["cache_file"] if File.file? @config["cache_file"]
  @last_update ||= {}

  # Create the originals directory.
  FileUtils.mkdir_p @config["archive_dir"]

  # Iterate over all images, optimizing as necessary.
  Dir.glob(@config["image_glob"]) { |image| analyze image }

  # Save modifications back to the cache file.
  File.open(@config["cache_file"], "w") { |file| file.write @last_update.to_yaml }
end

#optimize(image) ⇒ Object

In-place image optimization per the ImageOptim library.



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# File 'lib/jekyll-image-optim.rb', line 79

def optimize(image)
  puts "Optimizing #{image}"
  FileUtils.copy image, archival_filename(image)
  @image_optim.optimize_image! image
  @last_update[image] = File.mtime image
end