Merge pull request #58 from curationexperts/sampling_factor

Set Jpeg sampling factor and strip EXIF tags

app/services/riiif/imagemagick_command_factory.rb

@@ -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

spec/models/riiif/image_spec.rb

@@ -6,7 +6,9 @@
   subject { described_class.new('world') }
   describe 'happy path' do
     before do
-      expect(subject.image).to receive(:execute).with("convert -quality 85 #{filename} jpg:-").and_return('imagedata')
+      expect(subject.image).to receive(:execute)
+        .with("convert -quality 85 -sampling-factor 4:2:0 -strip #{filename} jpg:-")
+        .and_return('imagedata')
     end
     it 'renders' do
       expect(subject.render('size' => 'full', format: 'jpg')).to eq 'imagedata'
@@ -63,25 +65,25 @@
   describe 'mogrify' do
     describe 'region' do
       it 'returns the original when specifing full size' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -strip #{filename} png:-")
         subject.render(region: 'full', format: 'png')
       end
       it 'handles absolute geometry' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert -crop 60x75+80+15 #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -crop 60x75+80+15 -strip #{filename} png:-")
         subject.render(region: '80,15,60,75', format: 'png')
       end
 
       it 'handles percent geometry' do
         expect(Riiif::CommandRunner).to receive(:execute)
           .with("identify -format %hx%w #{filename}").and_return('131x175')
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert -crop 80%x70+18+13 #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -crop 80%x70+18+13 -strip #{filename} png:-")
         subject.render(region: 'pct:10,10,80,70', format: 'png')
       end
 
       it 'handles square geometry' do
         expect(Riiif::CommandRunner).to receive(:execute)
           .with("identify -format %hx%w #{filename}").and_return('131x175')
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert -crop 131x131+22+0 #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -crop 131x131+22+0 -strip #{filename} png:-")
         subject.render(region: 'square', format: 'png')
       end
       it 'raises an error for invalid geometry' do
@@ -91,31 +93,31 @@
 
     describe 'resize' do
       it 'returns the original when specifing full size' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -strip #{filename} png:-")
         subject.render(size: 'full', format: 'png')
       end
       it 'handles integer percent sizes' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize 50% #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize 50% -strip #{filename} png:-")
         subject.render(size: 'pct:50', format: 'png')
       end
       it 'handles float percent sizes' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize 12.5% #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize 12.5% -strip #{filename} png:-")
         subject.render(size: 'pct:12.5', format: 'png')
       end
       it 'handles w,' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize 50 #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize 50 -strip #{filename} png:-")
         subject.render(size: '50,', format: 'png')
       end
       it 'handles ,h' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize x50 #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize x50 -strip #{filename} png:-")
         subject.render(size: ',50', format: 'png')
       end
       it 'handles w,h' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize 150x75! #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize 150x75! -strip #{filename} png:-")
         subject.render(size: '150,75', format: 'png')
       end
       it 'handles bestfit (!w,h)' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize 150x75 #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -resize 150x75 -strip #{filename} png:-")
         subject.render(size: '!150,75', format: 'png')
       end
       it 'raises an error for invalid size' do
@@ -125,12 +127,12 @@
 
     describe 'rotate' do
       it 'returns the original when specifing full size' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -strip #{filename} png:-")
         subject.render(rotation: '0', format: 'png')
       end
       it 'handles floats' do
         expect(Riiif::CommandRunner).to receive(:execute)
-          .with("convert -virtual-pixel white +distort srt 22.5 #{filename} png:-")
+          .with("convert -virtual-pixel white +distort srt 22.5 -strip #{filename} png:-")
         subject.render(rotation: '22.5', format: 'png')
       end
       it 'raises an error for invalid angle' do
@@ -140,20 +142,20 @@
 
     describe 'quality' do
       it 'returns the original when specifing default' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -strip #{filename} png:-")
         subject.render(quality: 'default', format: 'png')
       end
       it 'returns the original when specifing color' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -strip #{filename} png:-")
         subject.render(quality: 'color', format: 'png')
       end
       it 'converts to grayscale' do
-        expect(Riiif::CommandRunner).to receive(:execute).with("convert -colorspace Gray #{filename} png:-")
+        expect(Riiif::CommandRunner).to receive(:execute).with("convert -colorspace Gray -strip #{filename} png:-")
         subject.render(quality: 'grey', format: 'png')
       end
       it 'converts to bitonal' do
         expect(Riiif::CommandRunner).to receive(:execute)
-          .with("convert -colorspace Gray -type Bilevel #{filename} png:-")
+          .with("convert -colorspace Gray -type Bilevel -strip #{filename} png:-")
         subject.render(quality: 'bitonal', format: 'png')
       end
       it 'raises an error for invalid angle' do