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rakelib/generate_derivatives.rake

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+###############################################################################
+# TASK: generate_derivatives
+#
+# create small and thumb images for image and pdf files in the 'objects' folder
+###############################################################################
+
+require 'image_optim' unless Gem.win_platform?
+require 'mini_magick'
+
+def process_and_optimize_image(filename, file_type, output_filename, size, density)
+  image_optim = ImageOptim.new(svgo: false) unless Gem.win_platform?
+  if filename == output_filename && file_type == :image && !Gem.win_platform?
+    puts "Optimizing: #{filename}"
+    begin
+      image_optim.optimize_image!(output_filename)
+    rescue StandardError => e
+      puts "Error optimizing #{filename}: #{e.message}"
+    end
+  elsif filename == output_filename && file_type == :pdf
+    puts "Skipping: #{filename}"
+  else
+    puts "Creating: #{output_filename}"
+    begin
+      if file_type == :pdf
+        inputfile = "#{filename}[0]"
+        magick = MiniMagick.convert
+        magick.density(density)
+        magick << inputfile
+        magick.resize(size)
+        magick.flatten
+        magick << output_filename
+        magick.call
+      else
+        magick = MiniMagick.convert
+        magick << filename
+        magick.resize(size)
+        magick.flatten
+        magick << output_filename
+        magick.call
+      end
+      image_optim.optimize_image!(output_filename) unless Gem.win_platform?
+    rescue StandardError => e
+      puts "Error creating #{filename}: #{e.message}"
+    end
+  end
+end
+
+
+desc 'Generate derivative image files from collection objects'
+task :generate_derivatives, [:thumbs_size, :small_size, :density, :missing, :compress_originals, :input_dir] do |_t, args|
+  # set default arguments
+  # default image size is based on max pixel width they will appear in the base template features
+  args.with_defaults(
+    thumbs_size: '450x',
+    small_size: '800x800',
+    density: '300',
+    missing: 'true',
+    compress_originals: 'false',
+    input_dir: 'objects'
+  )
+
+  # set the folder locations
+  objects_dir = args.input_dir
+  thumb_image_dir = objects_dir + '/thumbs'
+  small_image_dir = objects_dir + '/small'
+
+  # Ensure that the output directories exist.
+  [objects_dir, thumb_image_dir, small_image_dir].each do |dir|
+    FileUtils.mkdir_p(dir) unless Dir.exist?(dir)
+  end
+
+  # support these file types
+  EXTNAME_TYPE_MAP = {
+    '.jpeg' => :image,
+    '.jpg' => :image,
+    '.pdf' => :pdf,
+    '.png' => :image,
+    '.tif' => :image,
+    '.tiff' => :image
+  }.freeze
+
+  # CSV output
+  list_name = File.join(objects_dir, 'object_list.csv')
+  field_names = 'filename,object_location,image_small,image_thumb'.split(',')
+  CSV.open(list_name, 'w') do |csv|
+    csv << field_names
+
+    # Iterate over all files in the objects directory.
+    Dir.glob(File.join(objects_dir, '*')).each do |filename|
+      # Skip subdirectories and the README.md file.
+      if File.directory?(filename) || File.basename(filename) == 'README.md' || File.basename(filename) == 'object_list.csv'
+        next
+      end
+
+      # Determine the file type and skip if unsupported.
+      extname = File.extname(filename).downcase
+      file_type = EXTNAME_TYPE_MAP[extname]
+      unless file_type
+        puts "Skipping file with unsupported extension: #{filename}"
+        csv << ["#{File.basename(filename)}", "/#{filename}", nil, nil]
+        next
+      end
+
+      # Get the lowercase filename without any leading path and extension.
+      base_filename = File.basename(filename, '.*').downcase
+
+      # Optimize the original image.
+      if args.compress_originals == 'true'
+        puts "Optimizing: #{filename}"
+        process_and_optimize_image(filename, file_type, filename, nil, nil)
+      end
+
+      # Generate the thumb image.
+      thumb_filename = File.join(thumb_image_dir, "#{base_filename}_th.jpg")
+      if args.missing == 'false' || !File.exist?(thumb_filename)
+        process_and_optimize_image(filename, file_type, thumb_filename, args.thumbs_size, args.density)
+      else
+        puts "Skipping: #{thumb_filename} already exists"
+      end
+
+      # Generate the small image.
+      small_filename = File.join([small_image_dir, "#{base_filename}_sm.jpg"])
+      if (args.missing == 'false') || !File.exist?(small_filename)
+        process_and_optimize_image(filename, file_type, small_filename, args.small_size, args.density)
+      else
+        puts "Skipping: #{small_filename} already exists"
+      end
+      csv << ["#{File.basename(filename)}", "/#{filename}", "/#{small_filename}", "/#{thumb_filename}"]
+    end
+  end
+  puts "\e[32mSee '#{list_name}' for list of objects and derivatives created.\e[0m"
+end