Update picture tag

Gemfile

@@ -2,6 +2,7 @@ source 'https://rubygems.org'
 
 gem 'rake'
 
+gem 'fastimage'
 gem 'mini_magick'
 
 gem 'jekyll'

Gemfile.lock

@@ -85,6 +85,7 @@ PLATFORMS
 DEPENDENCIES
   bourbon
   facets
+  fastimage
   jekyll
   jekyll-archives
   jekyll-assets

_plugins/picture_tag.rb

@@ -20,6 +20,7 @@ require 'fileutils'
 require 'pathname'
 require 'digest/md5'
 require 'mini_magick'
+require 'fastimage'
 
 module Jekyll
 
@@ -38,6 +39,7 @@ module Jekyll
       # Gather settings
       site = context.registers[:site]
       settings = site.config['picture']
+      url = site.config['url']
       markup = /^(?:(?<preset>[^\s.:\/]+)\s+)?(?<image_src>[^\s]+\.[a-zA-Z0-9]{3,4})\s*(?<source_src>(?:(source_[^\s.:\/]+:\s+[^\s]+\.[a-zA-Z0-9]{3,4})\s*)+)?(?<html_attr>[\s\S]+)?$/.match(render_markup)
       preset = settings['presets'][ markup[:preset] ] || settings['presets']['default']
 
@@ -149,17 +151,26 @@ module Jekyll
       if settings['markup'] == 'picture'
 
         source_tags = ''
-        source_keys.each { |source|
+        source_keys.each do |source|
           media = " media=\"#{instance[source]['media']}\"" unless source == 'source_default'
-          source_tags += "#{markdown_escape * 4}<source srcset=\"#{instance[source][:generated_src]}\"#{media}>\n"
-        }
+          source_tags += "#{markdown_escape * 4}<source srcset=\"#{url}#{instance[source][:generated_src]}\"#{media}>\n"
+        end
 
         # Note: we can't indent html output because markdown parsers will turn 4 spaces into code blocks
         # Note: Added backslash+space escapes to bypass markdown parsing of indented code below -WD
         picture_tag = "<picture>\n"\
                       "#{source_tags}"\
-                      "#{markdown_escape * 4}<img srcset=\"#{instance['source_default'][:generated_src]}\" #{html_attr_string}>\n"\
+                      "#{markdown_escape * 4}<img src=\"#{url}#{instance['source_default'][:generated_src]}\" #{html_attr_string}>\n"\
                       "#{markdown_escape * 2}</picture>\n"
+      elsif settings['markup'] == 'interchange'
+
+        interchange_data = Array.new
+        source_keys.reverse.each do |source|
+          interchange_data << "[#{url}#{instance[source][:generated_src]}, #{source == 'source_default' ? '(default)' : instance[source]['media']}]"
+        end
+
+        picture_tag = %Q{<img data-interchange="#{interchange_data.join ', '}" #{html_attr_string} />\n}
+        picture_tag += %Q{<noscript><img src="#{url}#{instance['source_default'][:generated_src]}" #{html_attr_string} /></noscript>}
 
       elsif settings['markup'] == 'img'
         # TODO implement <img srcset/sizes>
@@ -170,16 +181,21 @@ module Jekyll
     end
 
     def generate_image(instance, site_source, site_dest, image_source, image_dest, baseurl)
-      image = MiniMagick::Image.open(File.join(site_source, image_source, instance[:src]))
-      digest = Digest::MD5.hexdigest(image.to_blob).slice!(0..5)
+      begin
+        digest = Digest::MD5.hexdigest(File.read(File.join(site_source, image_source, instance[:src]))).slice!(0..5)
+      rescue Errno::ENOENT
+        warn "Warning:".yellow + " source image #{instance[:src]} is missing."
+        return ""
+      end
 
       image_dir = File.dirname(instance[:src])
       ext = File.extname(instance[:src])
       basename = File.basename(instance[:src], ext)
 
-      orig_width = image[:width].to_f
-      orig_height = image[:height].to_f
-      orig_ratio = orig_width/orig_height
+      size = FastImage.size(File.join(site_source, image_source, instance[:src]))
+      orig_width = size[0]
+      orig_height = size[1]
+      orig_ratio = orig_width*1.0/orig_height
 
       gen_width = if instance[:width]
                     instance[:width].to_f
@@ -219,6 +235,7 @@ module Jekyll
         # Let people know their images are being generated
         puts "Generating #{gen_name}"
 
+        image = MiniMagick::Image.open(File.join(site_source, image_source, instance[:src]))
         # Scale and crop
         image.combine_options do |i|
           i.resize "#{gen_width}x#{gen_height}^"
@@ -226,7 +243,7 @@ module Jekyll
           i.crop "#{gen_width}x#{gen_height}+0+0"
         end
 
-        image.quality 85
+        image.quality 75
 
         image.write gen_dest_file
       end