Convert pngquant tasks into shell script, support file arguments

bin/pngquant

+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'rails'
+require 'png_quantizator'
+require 'parallel'
+require 'rainbow/ext/string'
+require_relative '../tooling/lib/tooling/images'
+
+return if Rails.env.production?
+
+def usage
+  puts <<~EOF
+    Usage: #{$0} [compress|lint] [PATH..]
+
+      compress  Compress all documentation PNG images using pngquant.
+      lint      Checks that all documentation PNG images have been compressed with pngquant.
+
+      PATH      One or more files or directories. If empty, `doc/**/*.png` is used.
+
+  EOF
+end
+
+command = ARGV.shift
+paths = ARGV.presence || ['doc']
+
+files = paths.flat_map do |path|
+  File.directory?(path) ? Dir.glob(File.join(path, '/**/*.png')) : path
+end
+
+case command
+when 'compress'
+  puts "Compressing #{files.size} PNG files"
+
+  Parallel.each(files) do |file|
+    was_uncompressed, savings = Tooling::Image.compress_image(file)
+
+    if was_uncompressed
+      puts "#{file} was reduced by #{savings} bytes"
+    end
+  end
+when 'lint'
+  puts "Checking #{files.size} PNG files"
+
+  uncompressed_files = Parallel.map(files) do |file|
+    is_uncompressed, _ = Tooling::Image.compress_image(file, true)
+    if is_uncompressed
+      puts "Uncompressed file detected: ".color(:red) + file
+      file
+    end
+  end.compact
+
+  if uncompressed_files.empty?
+    puts "All documentation images are optimally compressed!".color(:green)
+  else
+    warn(
+      "The #{uncompressed_files.size} image(s) above have not been optimally compressed using pngquant.".color(:red),
+      'Please run "bin/pngquant compress" and commit the result.'
+    )
+    abort
+  end
+else
+  usage
+end

doc/development/documentation/styleguide/index.md

@@ -1141,7 +1141,7 @@ known tool is [`pngquant`](https://pngquant.org/), which is cross-platform and
 open source. Install it by visiting the official website and following the
 instructions for your OS.
 
-GitLab has a [Rake task](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/tasks/pngquant.rake)
+GitLab has a [Ruby script](https://gitlab.com/gitlab-org/gitlab/-/blob/master/bin/pngquant)
 that you can use to automate the process. In the root directory of your local
 copy of `https://gitlab.com/gitlab-org/gitlab`, run in a terminal:
 
@@ -1149,19 +1149,26 @@ copy of `https://gitlab.com/gitlab-org/gitlab`, run in a terminal:
   been compressed:
 
   ```shell
-  bundle exec rake pngquant:lint
+  bin/pngquant lint
   ```
 
 - Compress all documentation PNG images using `pngquant`:
 
   ```shell
-  bundle exec rake pngquant:compress
+  bin/pngquant compress
   ```
 
-The only caveat is that the task runs on all images under `doc/`, not only the
-ones you might have included in a merge request. In that case, you can run the
-compress task and only commit the images that are relevant to your merge
-request.
+- Compress specific files:
+
+  ```shell
+  bin/pngquant compress doc/user/img/award_emoji_select.png doc/user/img/markdown_logo.png
+  ```
+
+- Compress all PNG files in a specific directory:
+
+  ```shell
+  bin/pngquant compress doc/user/img
+  ```
 
 ## Videos
 

lib/tasks/pngquant.rake

-# frozen_string_literal: true
-
-return if Rails.env.production?
-
-require 'png_quantizator'
-require 'parallel'
-require_relative '../../tooling/lib/tooling/images'
-
-# The amount of variance (in bytes) allowed in
-# file size when testing for compression size
-
-namespace :pngquant do
-  # Returns an array of all images eligible for compression
-  def doc_images
-    Dir.glob('doc/**/*.png', File::FNM_CASEFOLD)
-  end
-
-  desc 'GitLab | Pngquant | Compress all documentation PNG images using pngquant'
-  task :compress do
-    files = doc_images
-    puts "Compressing #{files.size} PNG files in doc/**"
-
-    Parallel.each(files) do |file|
-      was_uncompressed, savings = Tooling::Image.compress_image(file)
-
-      if was_uncompressed
-        puts "#{file} was reduced by #{savings} bytes"
-      end
-    end
-  end
-
-  desc 'GitLab | Pngquant | Checks that all documentation PNG images have been compressed with pngquant'
-  task :lint do
-    files = doc_images
-    puts "Checking #{files.size} PNG files in doc/**"
-
-    uncompressed_files = Parallel.map(files) do |file|
-      is_uncompressed, _ = Tooling::Image.compress_image(file, true)
-      if is_uncompressed
-        puts "Uncompressed file detected: ".color(:red) + file
-        file
-      end
-    end.compact
-
-    if uncompressed_files.empty?
-      puts "All documentation images are optimally compressed!".color(:green)
-    else
-      warn(
-        "The #{uncompressed_files.size} image(s) above have not been optimally compressed using pngquant.".color(:red),
-        'Please run "bin/rake pngquant:compress" and commit the result.'
-      )
-      abort
-    end
-  end
-end