Change image processing from ImageMagick to libvips

.devcontainer/Dockerfile

@@ -9,7 +9,7 @@ RUN su vscode -c "source /usr/local/share/nvm/nvm.sh && nvm install ${NODE_VERSI
 
 # [Optional] Uncomment this section to install additional OS packages.
 RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
-    && apt-get -y install --no-install-recommends libicu-dev libidn11-dev ffmpeg imagemagick libpam-dev
+    && apt-get -y install --no-install-recommends libicu-dev libidn11-dev ffmpeg libvips42 libpam-dev
 
 # [Optional] Uncomment this line to install additional gems.
 RUN gem install foreman

.github/workflows/check-i18n.yml

@@ -21,6 +21,8 @@ jobs:
 
       - name: Set up Ruby environment
         uses: ./.github/actions/setup-ruby
+        with:
+          additional-system-dependencies: libvips42
 
       - name: Set up Javascript environment
         uses: ./.github/actions/setup-javascript

.github/workflows/test-migrations-one-step.yml

@@ -74,6 +74,8 @@ jobs:
 
       - name: Set up Ruby environment
         uses: ./.github/actions/setup-ruby
+        with:
+          additional-system-dependencies: libvips42
 
       - name: Create database
         run: './bin/rails db:create'

.github/workflows/test-migrations-two-step.yml

@@ -74,6 +74,8 @@ jobs:
 
       - name: Set up Ruby environment
         uses: ./.github/actions/setup-ruby
+        with:
+          additional-system-dependencies: libvips42
 
       - name: Create database
         run: './bin/rails db:create'

.github/workflows/test-ruby.yml

@@ -39,6 +39,8 @@ jobs:
 
       - name: Set up Ruby environment
         uses: ./.github/actions/setup-ruby
+        with:
+          additional-system-dependencies: libvips42
 
       - name: Set up Javascript environment
         uses: ./.github/actions/setup-javascript
@@ -133,7 +135,7 @@ jobs:
         uses: ./.github/actions/setup-ruby
         with:
           ruby-version: ${{ matrix.ruby-version}}
-          additional-system-dependencies: ffmpeg imagemagick libpam-dev
+          additional-system-dependencies: ffmpeg libvips42 libpam-dev
 
       - name: Load database schema
         run: './bin/rails db:create db:schema:load db:seed'
@@ -205,7 +207,7 @@ jobs:
         uses: ./.github/actions/setup-ruby
         with:
           ruby-version: ${{ matrix.ruby-version}}
-          additional-system-dependencies: ffmpeg imagemagick
+          additional-system-dependencies: ffmpeg libvips42
 
       - name: Set up Javascript environment
         uses: ./.github/actions/setup-javascript
@@ -309,7 +311,7 @@ jobs:
         uses: ./.github/actions/setup-ruby
         with:
           ruby-version: ${{ matrix.ruby-version}}
-          additional-system-dependencies: ffmpeg imagemagick
+          additional-system-dependencies: ffmpeg libvips42
 
       - name: Set up Javascript environment
         uses: ./.github/actions/setup-javascript

Dockerfile

@@ -97,7 +97,7 @@ RUN \
     curl \
     ffmpeg \
     file \
-    imagemagick \
+    libvips42 \
     libjemalloc2 \
     patchelf \
     procps \

Gemfile

@@ -23,6 +23,7 @@ gem 'fog-core', '<= 2.4.0'
 gem 'fog-openstack', '~> 1.0', require: false
 gem 'kt-paperclip', '~> 7.2'
 gem 'md-paperclip-azure', '~> 2.2', require: false
+gem 'ruby-vips', '~> 2.2'
 
 gem 'active_model_serializers', '~> 0.10'
 gem 'addressable', '~> 2.8'

Gemfile.lock

@@ -681,6 +681,8 @@ GEM
     ruby-saml (1.16.0)
       nokogiri (>= 1.13.10)
       rexml
+    ruby-vips (2.2.1)
+      ffi (~> 1.12)
     ruby2_keywords (0.0.5)
     rubyzip (2.3.2)
     rufus-scheduler (3.9.1)
@@ -925,6 +927,7 @@ DEPENDENCIES
   rubocop-rspec
   ruby-prof
   ruby-progressbar (~> 1.13)
+  ruby-vips (~> 2.2)
   rubyzip (~> 2.3)
   sanitize (~> 6.0)
   scenic (~> 1.7)

app/models/concerns/account/avatar.rb

@@ -9,7 +9,7 @@ module Account::Avatar
   class_methods do
     def avatar_styles(file)
       styles = { original: { geometry: '400x400#', file_geometry_parser: FastGeometryParser } }
-      styles[:static] = { geometry: '400x400#', format: 'png', convert_options: '-coalesce', file_geometry_parser: FastGeometryParser } if file.content_type == 'image/gif'
+      styles[:static] = { geometry: '400x400#', format: 'png', file_geometry_parser: FastGeometryParser } if file.content_type == 'image/gif'
       styles
     end
 
@@ -18,7 +18,7 @@ module Account::Avatar
 
   included do
     # Avatar upload
-    has_attached_file :avatar, styles: ->(f) { avatar_styles(f) }, convert_options: { all: '+profile "!icc,*" +set date:modify +set date:create +set date:timestamp' }, processors: [:lazy_thumbnail]
+    has_attached_file :avatar, styles: ->(f) { avatar_styles(f) }, processors: [:lazy_thumbnail]
     validates_attachment_content_type :avatar, content_type: IMAGE_MIME_TYPES
     validates_attachment_size :avatar, less_than: LIMIT
     remotable_attachment :avatar, LIMIT, suppress_errors: false

app/models/concerns/account/header.rb

@@ -10,7 +10,7 @@ module Account::Header
   class_methods do
     def header_styles(file)
       styles = { original: { pixels: MAX_PIXELS, file_geometry_parser: FastGeometryParser } }
-      styles[:static] = { format: 'png', convert_options: '-coalesce', file_geometry_parser: FastGeometryParser } if file.content_type == 'image/gif'
+      styles[:static] = { format: 'png', file_geometry_parser: FastGeometryParser } if file.content_type == 'image/gif'
       styles
     end
 
@@ -19,7 +19,7 @@ module Account::Header
 
   included do
     # Header upload
-    has_attached_file :header, styles: ->(f) { header_styles(f) }, convert_options: { all: '+profile "!icc,*" +set date:modify +set date:create +set date:timestamp' }, processors: [:lazy_thumbnail]
+    has_attached_file :header, styles: ->(f) { header_styles(f) }, processors: [:lazy_thumbnail]
     validates_attachment_content_type :header, content_type: IMAGE_MIME_TYPES
     validates_attachment_size :header, less_than: LIMIT
     remotable_attachment :header, LIMIT, suppress_errors: false

app/models/media_attachment.rb

@@ -170,18 +170,13 @@ class MediaAttachment < ApplicationRecord
 
   DEFAULT_STYLES = [:original].freeze
 
-  GLOBAL_CONVERT_OPTIONS = {
-    all: '-quality 90 +profile "!icc,*" +set date:modify +set date:create +set date:timestamp -define jpeg:dct-method=float',
-  }.freeze
-
   belongs_to :account,          inverse_of: :media_attachments, optional: true
   belongs_to :status,           inverse_of: :media_attachments, optional: true
   belongs_to :scheduled_status, inverse_of: :media_attachments, optional: true
 
   has_attached_file :file,
                     styles: ->(f) { file_styles f },
-                    processors: ->(f) { file_processors f },
-                    convert_options: GLOBAL_CONVERT_OPTIONS
+                    processors: ->(f) { file_processors f }
 
   before_file_validate :set_type_and_extension
   before_file_validate :check_video_dimensions
@@ -192,8 +187,7 @@ class MediaAttachment < ApplicationRecord
 
   has_attached_file :thumbnail,
                     styles: THUMBNAIL_STYLES,
-                    processors: [:lazy_thumbnail, :blurhash_transcoder, :color_extractor],
-                    convert_options: GLOBAL_CONVERT_OPTIONS
+                    processors: [:lazy_thumbnail, :blurhash_transcoder, :color_extractor]
 
   validates_attachment_content_type :thumbnail, content_type: IMAGE_MIME_TYPES
   validates_attachment_size :thumbnail, less_than: IMAGE_LIMIT

app/models/preview_card.rb

@@ -55,7 +55,7 @@ class PreviewCard < ApplicationRecord
 
   has_one :trend, class_name: 'PreviewCardTrend', inverse_of: :preview_card, dependent: :destroy
 
-  has_attached_file :image, processors: [:thumbnail, :blurhash_transcoder], styles: ->(f) { image_styles(f) }, convert_options: { all: '-quality 90 +profile "!icc,*" +set date:modify +set date:create +set date:timestamp' }, validate_media_type: false
+  has_attached_file :image, processors: [:lazy_thumbnail, :blurhash_transcoder], styles: ->(f) { image_styles(f) }, validate_media_type: false
 
   validates :url, presence: true, uniqueness: true, url: true
   validates_attachment_content_type :image, content_type: IMAGE_MIME_TYPES

app/models/site_upload.rb

@@ -41,7 +41,7 @@ class SiteUpload < ApplicationRecord
     mascot: {}.freeze,
   }.freeze
 
-  has_attached_file :file, styles: ->(file) { STYLES[file.instance.var.to_sym] }, convert_options: { all: '-coalesce +profile "!icc,*" +set date:modify +set date:create +set date:timestamp' }, processors: [:lazy_thumbnail, :blurhash_transcoder, :type_corrector]
+  has_attached_file :file, styles: ->(file) { STYLES[file.instance.var.to_sym] }, processors: [:lazy_thumbnail, :blurhash_transcoder, :type_corrector]
 
   validates_attachment_content_type :file, content_type: %r{\Aimage/.*\z}
   validates :file, presence: true

config/imagemagick/policy.xml

@@ -1,27 +0,0 @@
-<policymap>
-  <!-- Set some basic system resource limits -->
-  <policy domain="resource" name="time" value="60" />
-
-  <policy domain="module" rights="none" pattern="URL" />
-
-  <policy domain="filter" rights="none" pattern="*" />
-
-  <!--
-    Ideally, we would restrict ImageMagick to only accessing its own
-    disk-backed pixel cache as well as Mastodon-created Tempfiles.
-
-    However, those paths depend on the operating system and environment
-    variables, so they can only be known at runtime.
-
-    Furthermore, those paths are not necessarily shared across Mastodon
-    processes, so even creating a policy.xml at runtime is impractical.
-
-    For the time being, only disable indirect reads.
-  -->
-  <policy domain="path" rights="none" pattern="@*" />
-
-  <!-- Disallow any coder by default, and only enable ones required by Mastodon -->
-  <policy domain="coder" rights="none" pattern="*" />
-  <policy domain="coder" rights="read | write" pattern="{JPEG,PNG,GIF,WEBP,HEIC,AVIF}" />
-  <policy domain="coder" rights="write" pattern="{HISTOGRAM,RGB,INFO}" />
-</policymap>

config/initializers/vips.rb

@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+Vips.block_untrusted(true) if Vips.at_least_libvips?(8, 13)

lib/paperclip/blurhash_transcoder.rb

@@ -5,10 +5,9 @@ module Paperclip
     def make
       return @file unless options[:style] == :small || options[:blurhash]
 
-      pixels   = convert(':source -depth 8 RGB:-', source: File.expand_path(@file.path)).unpack('C*')
-      geometry = options.fetch(:file_geometry_parser).from_file(@file)
+      image = Vips::Image.thumbnail(@file.path, 100)
 
-      attachment.instance.blurhash = Blurhash.encode(geometry.width, geometry.height, pixels, **(options[:blurhash] || {}))
+      attachment.instance.blurhash = Blurhash.encode(image.width, image.height, image.to_a.flatten, **(options[:blurhash] || {}))
 
       @file
     end

lib/paperclip/color_extractor.rb

@@ -7,15 +7,18 @@ module Paperclip
     MIN_CONTRAST        = 3.0
     ACCENT_MIN_CONTRAST = 2.0
     FREQUENCY_THRESHOLD = 0.01
+    BINS = 10
 
     def make
-      depth = 8
+      image = Vips::Image.new_from_file(@file.path)
 
-      # Determine background palette by getting colors close to the image's edge only
-      background_palette = palette_from_histogram(convert(':source -alpha set -gravity Center -region 75%x75% -fill None -colorize 100% -alpha transparent +region -format %c -colors :quantity -depth :depth histogram:info:', source: File.expand_path(@file.path), quantity: 10, depth: depth), 10)
+      edge_image = begin
+        transparent = Vips::Image.black(image.width * 0.75, image.height * 0.75)
+        image.insert(transparent, (image.width * 0.25) / 2, (image.height * 0.25) / 2)
+      end
 
-      # Determine foreground palette from the whole image
-      foreground_palette = palette_from_histogram(convert(':source -format %c -colors :quantity -depth :depth histogram:info:', source: File.expand_path(@file.path), quantity: 10, depth: depth), 10)
+      background_palette = palette_from_image(edge_image)
+      foreground_palette = palette_from_image(image)
 
       background_color   = background_palette.first || foreground_palette.first
       foreground_colors  = []
@@ -78,6 +81,28 @@ module Paperclip
 
     private
 
+    def palette_from_image(image)
+      histogram = image.hist_find_ndim(bins: BINS)
+      _, colors = histogram.max(size: 10, out_array: true, x_array: true, y_array: true)
+
+      colors['out_array'].map.with_index do |v, i|
+        x = colors['x_array'][i]
+        y = colors['y_array'][i]
+
+        rgb_from_xyv(histogram, x, y, v)
+      end
+    end
+
+    # rubocop:disable Naming/MethodParameterName
+    def rgb_from_xyv(image, x, y, v)
+      pixel = image.getpoint(x, y)
+      z = pixel.find_index(v)
+      r = (x + 0.5) * 256 / BINS
+      g = (y + 0.5) * 256 / BINS
+      b = (z + 0.5) * 256 / BINS
+      ColorDiff::Color::RGB.new(r, g, b)
+    end
+
     def w3c_contrast(color1, color2)
       luminance1 = (color1.to_xyz.y * 0.01) + 0.05
       luminance2 = (color2.to_xyz.y * 0.01) + 0.05
@@ -89,7 +114,6 @@ module Paperclip
       end
     end
 
-    # rubocop:disable Naming/MethodParameterName
     def rgb_to_hsl(r, g, b)
       r /= 255.0
       g /= 255.0
@@ -170,18 +194,6 @@ module Paperclip
       ColorDiff::Color::RGB.new(*hsl_to_rgb(hue, saturation, light))
     end
 
-    def palette_from_histogram(result, quantity)
-      frequencies       = result.scan(/([0-9]+):/).flatten.map(&:to_f)
-      hex_values        = result.scan(/\#([0-9A-Fa-f]{6,8})/).flatten
-      total_frequencies = frequencies.sum.to_f
-
-      frequencies.map.with_index { |f, i| [f / total_frequencies, hex_values[i]] }
-                 .sort_by { |r| -r[0] }
-                 .reject { |r| r[1].size == 8 && r[1].end_with?('00') }
-                 .map { |r| ColorDiff::Color::RGB.new(*r[1][0..5].scan(/../).map { |c| c.to_i(16) }) }
-                 .slice(0, quantity)
-    end
-
     def rgb_to_hex(rgb)
       format('#%02x%02x%02x', rgb.r, rgb.g, rgb.b)
     end

lib/paperclip/lazy_thumbnail.rb

@@ -1,24 +1,109 @@
 # frozen_string_literal: true
 
 module Paperclip
-  class LazyThumbnail < Paperclip::Thumbnail
+  class LazyThumbnail < Paperclip::Processor
+    ALLOWED_FIELDS = %w(
+      icc-profile-data
+      page-height
+      loop
+      delay
+    ).freeze
+
+    class PixelGeometryParser
+      def self.parse(current_geometry, pixels)
+        width  = Math.sqrt(pixels * (current_geometry.width.to_f / current_geometry.height)).round.to_i
+        height = Math.sqrt(pixels * (current_geometry.height.to_f / current_geometry.width)).round.to_i
+
+        Paperclip::Geometry.new(width, height)
+      end
+    end
+
+    def initialize(file, options = {}, attachment = nil)
+      super
+
+      @crop = options[:geometry].to_s[-1, 1] == '#'
+      @current_geometry = options.fetch(:file_geometry_parser, Geometry).from_file(@file)
+      @target_geometry = options[:pixels] ? PixelGeometryParser.parse(@current_geometry, options[:pixels]) : options.fetch(:string_geometry_parser, Geometry).parse(options[:geometry].to_s)
+      @format = options[:format]
+      @current_format = File.extname(@file.path)
+      @basename = File.basename(@file.path, @current_format)
+
+      correct_target_geometry!
+    end
+
     def make
       return File.open(@file.path) unless needs_convert?
 
-      if options[:geometry]
-        min_side = [@current_geometry.width, @current_geometry.height].min.to_i
-        options[:geometry] = "#{min_side}x#{min_side}#" if @target_geometry.square? && min_side < @target_geometry.width
-      elsif options[:pixels]
-        width  = Math.sqrt(options[:pixels] * (@current_geometry.width.to_f / @current_geometry.height)).round.to_i
-        height = Math.sqrt(options[:pixels] * (@current_geometry.height.to_f / @current_geometry.width)).round.to_i
-        options[:geometry] = "#{width}x#{height}>"
-      end
+      dst = TempfileFactory.new.generate([@basename, @format ? ".#{@format}" : @current_format].join)
 
-      Paperclip::Thumbnail.make(file, options, attachment)
+      transformed_image.write_to_file(dst.path, **save_options)
+
+      dst
     end
 
     private
 
+    def correct_target_geometry!
+      min_side = [@current_geometry.width, @current_geometry.height].min.to_i
+      @target_geometry = Paperclip::Geometry.new(min_side, min_side) if @target_geometry&.square? && min_side < @target_geometry.width
+    end
+
+    def transformed_image
+      # libvips has some optimizations for resizing an image on load. If we don't need to
+      # resize the image, we have to load it a different way.
+      if @target_geometry.nil?
+        return Vips::Image.new_from_file(preserve_animation? ? "#{@file.path}[n=-1]" : @file.path).copy.mutate do |mutable|
+          (mutable.get_fields - ALLOWED_FIELDS).each do |field|
+            mutable.remove!(field)
+          end
+        end
+      end
+
+      # libvips thumbnail operation does not work correctly on animated GIFs. If we need to
+      # preserve the animation, we have to load all the frames and then manually crop
+      # them to then reassemble.
+      if preserve_animation?
+        original_image = Vips::Image.new_from_file("#{@file.path}[n=-1]")
+        page_height = original_image.get('page-height')
+        n_frames = original_image.height / page_height
+        resized_image = original_image.thumbnail_image(@target_geometry.width, height: @target_geometry.height * n_frames, size: :down)
+        new_page_height = resized_image.get('page-height')
+
+        return resized_image unless @crop
+
+        frames = (0...n_frames).map do |i|
+          resized_image.crop(0, i * new_page_height, @target_geometry.width, @target_geometry.height)
+        end
+
+        Vips::Image.arrayjoin(frames, across: 1).copy.mutate do |mutable|
+          mutable.set!('page-height', @target_geometry.height)
+        end
+      else
+        Vips::Image.thumbnail(@file.path, @target_geometry.width, height: @target_geometry.height, **thumbnail_options).mutate do |mutable|
+          (mutable.get_fields - ALLOWED_FIELDS).each do |field|
+            mutable.remove!(field)
+          end
+        end
+      end
+    end
+
+    def thumbnail_options
+      @crop ? { crop: :centre } : { size: :down }
+    end
+
+    def save_options
+      case @format
+      when 'jpg'
+        { Q: 90, interlace: true }
+      else
+        {}
+      end
+    end
+
+    def preserve_animation?
+      @format == 'gif' || (@format.blank? && @current_format == '.gif')
+    end
+
     def needs_convert?
       needs_different_geometry? || needs_different_format? || needs_metadata_stripping?
     end
@@ -29,7 +114,7 @@ module Paperclip
     end
 
     def needs_different_format?
-      @format.present? && @current_format != @format
+      @format.present? && @current_format != ".#{@format}"
     end
 
     def needs_metadata_stripping?