discourse/lib/image_optimizer.rb

97 lines
2.5 KiB
Ruby

#
# This class is used to download and optimize images.
#
require 'image_sorcery'
require 'digest/sha1'
require 'open-uri'
class ImageOptimizer
attr_accessor :url
# url is a url of an image ex:
# 'http://site.com/image.png'
# '/uploads/site/image.png'
def initialize(url)
@url = url
# make sure directories exists
FileUtils.mkdir_p downloads_dir
FileUtils.mkdir_p optimized_dir
end
# return the path of an optimized image,
# if already cached return cached, else download and cache
# at the original size.
# if size is specified return a resized image
# if height or width are nil maintain aspect ratio
#
# Optimised image is the "most efficient" storage for an image
# at the basic level it runs through image_optim https://github.com/toy/image_optim
# it also has a failsafe that converts jpg to png or the opposite. if jpg size is 1.5*
# as efficient as png it flips formats.
def optimized_image_url (width = nil, height = nil)
begin
unless has_been_uploaded?
return @url unless SiteSetting.crawl_images?
# download the file if it hasn't been cached yet
download! unless File.exists?(cached_path)
end
# resize the image using Image Magick
result = ImageSorcery.new(cached_path).convert(optimized_path, resize: "#{width}x#{height}")
return optimized_url if result
@url
rescue
@url
end
end
private
def public_dir
@public_dir ||= "#{Rails.root}/public"
end
def downloads_dir
@downloads_dir ||= "#{public_dir}/downloads/#{RailsMultisite::ConnectionManagement.current_db}"
end
def optimized_dir
@optimized_dir ||= "#{public_dir}/images/#{RailsMultisite::ConnectionManagement.current_db}"
end
def has_been_uploaded?
@url.start_with?(Discourse.base_url_no_prefix)
end
def cached_path
@cached_path ||= if has_been_uploaded?
"#{public_dir}#{@url[Discourse.base_url_no_prefix.length..-1]}"
else
"#{downloads_dir}/#{file_name(@url)}"
end
end
def optimized_path
@optimized_path ||= "#{optimized_dir}/#{file_name(cached_path)}"
end
def file_name (uri)
image_info = FastImage.new(uri)
name = Digest::SHA1.hexdigest(uri)[0,16]
name << ".#{image_info.type}"
name
end
def download!
File.open(cached_path, "wb") do |f|
f.write open(@url, "rb", read_timeout: 20).read
end
end
def optimized_url
@optimized_url ||= Discourse::base_uri + "/images/#{RailsMultisite::ConnectionManagement.current_db}/#{file_name(cached_path)}"
end
end