imagemagick_command_factory.rb in riiif-1.4.0

- old
+ new
@@ -1,52 +1,90 @@
+# frozen_string_literal: true
+
 module Riiif
   # Builds a command to run a transformation using Imagemagick
   class ImagemagickCommandFactory
     # A helper method to instantiate and invoke build
     # @param [String] path the location of the file
     # @param [Transformation] transformation
     # @param [Integer] compression (85) the compression level to use (set 0 for no compression)
+    # @param [String] sampling_factor ("4:2:0") the chroma sample factor (set 0 for no compression)
+    # @param [Boolean] strip_metadata (true) do we want to strip EXIF tags?
     # @return [String] a command for running imagemagick to produce the requested output
-    def self.build(path, transformation, compression: 85)
-      new(path, transformation, compression: compression).build
+    def self.build(path, transformation, compression: 85, sampling_factor: '4:2:0', strip_metadata: true)
+      new(path, transformation,
+          compression: compression,
+          sampling_factor: sampling_factor,
+          strip_metadata: strip_metadata).build
     end
 
     # A helper method to instantiate and invoke build
     # @param [String] path the location of the file
     # @param [Transformation] transformation
     # @param [Integer] compression the compression level to use (set 0 for no compression)
-    def initialize(path, transformation, compression:)
+    def initialize(path, transformation, compression:, sampling_factor:, strip_metadata:)
       @path = path
       @transformation = transformation
       @compression = compression
+      @sampling_factor = sampling_factor
+      @strip_metadata = strip_metadata
     end
 
-    attr_reader :path, :transformation, :compression
+    attr_reader :path, :transformation, :compression, :sampling_factor, :strip_metadata
 
     # @return [String] a command for running imagemagick to produce the requested output
     def build
-      command = 'convert'
-      command << " -crop #{transformation.crop}" if transformation.crop
-      command << " -resize #{transformation.size}" if transformation.size
-      if transformation.rotation
-        command << " -virtual-pixel white +distort srt #{transformation.rotation}"
-      end
-
-      case transformation.quality
-      when 'grey'
-        command << ' -colorspace Gray'
-      when 'bitonal'
-        command << ' -colorspace Gray'
-        command << ' -type Bilevel'
-      end
-      command << " -quality #{compression}" if use_compression?
-      command << " #{path} #{transformation.format}:-"
-      command
+      [command, crop, size, rotation, colorspace, quality, sampling, metadata, output].join
     end
 
     private
 
+      def command
+        'convert'
+      end
+
       def use_compression?
-        compression > 0 && transformation.format == 'jpg'
+        compression > 0 && jpeg?
+      end
+
+      def jpeg?
+        transformation.format == 'jpg'.freeze
+      end
+
+      def output
+        " #{path} #{transformation.format}:-"
+      end
+
+      def crop
+        " -crop #{transformation.crop}" if transformation.crop
+      end
+
+      def size
+        " -resize #{transformation.size}" if transformation.size
+      end
+
+      def rotation
+        " -virtual-pixel white +distort srt #{transformation.rotation}" if transformation.rotation
+      end
+
+      def quality
+        " -quality #{compression}" if use_compression?
+      end
+
+      def metadata
+        ' -strip' if strip_metadata
+      end
+
+      def sampling
+        " -sampling-factor #{sampling_factor}" if jpeg?
+      end
+
+      def colorspace
+        case transformation.quality
+        when 'grey'
+          ' -colorspace Gray'
+        when 'bitonal'
+          ' -colorspace Gray -type Bilevel'
+        end
       end
   end
 end