Add support for Oxipng

Based on toy#167

Oxipng is a multi-threaded rust implementation of Optipng.

https://github.com/shssoichiro/oxipng

CHANGELOG.markdown

@@ -2,6 +2,8 @@
 
 ## unreleased
 
+* Add support for Oxipng [#167](https://github.com/toy/image_optim/issues/167) [@oblakeerickson](https://github.com/oblakeerickson)
+
 ## v0.28.0 (2020-12-18)
 
 * Fix and update list of markers in jpegoptim worker: allow to pass `com` instead of incorrect `comments` and add missing `xmp` and `none` [#188](https://github.com/toy/image_optim/issues/188) [@toy](https://github.com/toy)

lib/image_optim.rb

@@ -12,7 +12,7 @@
 require 'shellwords'
 
 %w[
-  pngcrush pngout advpng optipng pngquant
+  pngcrush pngout advpng optipng pngquant oxipng
   jhead jpegoptim jpegrecompress jpegtran
   gifsicle
   svgo

lib/image_optim/bin_resolver/bin.rb

@@ -109,7 +109,7 @@ def version_string
         case name
         when :advpng
           capture("#{escaped_path} --version 2> #{Path::NULL}")[/\bv(\d+(\.\d+)+|none)/, 1]
-        when :gifsicle, :jpegoptim, :optipng
+        when :gifsicle, :jpegoptim, :optipng, :oxipng
           capture("#{escaped_path} --version 2> #{Path::NULL}")[/\d+(\.\d+)+/]
         when :svgo, :pngquant
           capture("#{escaped_path} --version 2>&1")[/\d+(\.\d+)+/]

lib/image_optim/worker/oxipng.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require 'image_optim/worker'
+require 'image_optim/option_helpers'
+require 'image_optim/true_false_nil'
+
+class ImageOptim
+  class Worker
+    # https://github.com/shssoichiro/oxipng
+    class Oxipng < Worker
+      LEVEL_OPTION =
+      option(:level, 3, 'Optimization level preset: '\
+          '`0` is least, '\
+          '`6` is best') do |v|
+        OptionHelpers.limit_with_range(v.to_i, 0..6)
+      end
+
+      INTERLACE_OPTION =
+      option(:interlace, false, TrueFalseNil, 'Interlace: '\
+          '`true` - interlace on, '\
+          '`false` - interlace off, '\
+          '`nil` - as is in original image') do |v|
+        TrueFalseNil.convert(v)
+      end
+
+      STRIP_OPTION =
+      option(:strip, true, 'Remove all auxiliary chunks'){ |v| !!v }
+
+      def run_order
+        -4
+      end
+
+      def optimize(src, dst)
+        src.copy(dst)
+        args = %W[
+          -o #{level}
+          --quiet
+          #{dst}
+        ]
+        args.unshift "-i#{interlace ? 1 : 0}" unless interlace.nil?
+        if strip
+          args.unshift '--strip', 'all'
+        end
+        execute(:oxipng, *args) && optimized?(src, dst)
+      end
+
+      def optimized?(src, dst)
+        interlace ? dst.size? : super
+      end
+    end
+  end
+end

spec/image_optim/worker/oxipng_spec.rb

@@ -0,0 +1,89 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require 'image_optim/worker/oxipng'
+require 'image_optim/path'
+
+describe ImageOptim::Worker::Oxipng do
+  describe 'strip option' do
+    subject{ described_class.new(ImageOptim.new, options) }
+
+    let(:options){ {} }
+    let(:src){ instance_double(ImageOptim::Path, :copy => nil) }
+    let(:dst){ instance_double(ImageOptim::Path) }
+
+    before do
+      oxipng_bin = instance_double(ImageOptim::BinResolver::Bin)
+      allow(subject).to receive(:resolve_bin!).
+        with(:oxipng).and_return(oxipng_bin)
+
+      allow(subject).to receive(:optimized?)
+    end
+
+    context 'by default' do
+      it 'should add --strip all to arguments' do
+        expect(subject).to receive(:execute) do |_bin, *args|
+          expect(args.join(' ')).to match(/(^| )--strip all($| )/)
+        end
+
+        subject.optimize(src, dst)
+      end
+    end
+
+    context 'when strip is disabled' do
+      let(:options){ {:strip => false} }
+
+      it 'should not add --strip all to arguments' do
+        expect(subject).to receive(:execute) do |_bin, *args|
+          expect(args.join(' ')).not_to match(/(^| )--strip all($| )/)
+        end
+
+        subject.optimize(src, dst)
+      end
+    end
+  end
+
+  describe '#optimized?' do
+    let(:src){ instance_double(ImageOptim::Path, src_options) }
+    let(:dst){ instance_double(ImageOptim::Path, dst_options) }
+    let(:src_options){ {:size => 10} }
+    let(:dst_options){ {:size? => 9} }
+    let(:instance){ described_class.new(ImageOptim.new, instance_options) }
+    let(:instance_options){ {} }
+
+    subject{ instance.optimized?(src, dst) }
+
+    context 'when interlace option is enabled' do
+      let(:instance_options){ {:interlace => true} }
+
+      context 'when dst is empty' do
+        let(:dst_options){ {:size? => nil} }
+        it{ is_expected.to be_falsy }
+      end
+
+      context 'when dst is not empty' do
+        let(:dst_options){ {:size? => 20} }
+        it{ is_expected.to be_truthy }
+      end
+    end
+
+    context 'when interlace option is disabled' do
+      let(:instance_options){ {:interlace => false} }
+
+      context 'when dst is empty' do
+        let(:dst_options){ {:size? => nil} }
+        it{ is_expected.to be_falsy }
+      end
+
+      context 'when dst is greater than or equal to src' do
+        let(:dst_options){ {:size? => 10} }
+        it{ is_expected.to be_falsy }
+      end
+
+      context 'when dst is less than src' do
+        let(:dst_options){ {:size? => 9} }
+        it{ is_expected.to be_truthy }
+      end
+    end
+  end
+end