Module: SafeImage::JpegliBackend

Defined in:
lib/safe_image/jpegli_backend.rb

Constant Summary collapse

DIRECT_INPUTS = 
%w[png].freeze
CHROMA_SUBSAMPLING = 
%w[420 422 444].freeze
DEFAULT_QUALITY = 
85

Class Method Summary collapse

Class Method Details

.available? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/safe_image/jpegli_backend.rb', line 15

def available?
  Runner.available?("cjpegli")
end

.convert(input:, output:, quality: DEFAULT_QUALITY, chroma_subsampling: :auto, timeout: Runner::DEFAULT_TIMEOUT) ⇒ Object

Raises:



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# File 'lib/safe_image/jpegli_backend.rb', line 23

def convert(input:, output:, quality: DEFAULT_QUALITY, chroma_subsampling: :auto, timeout: Runner::DEFAULT_TIMEOUT)
  raise UnsupportedFormatError, "cjpegli is not installed" unless available?

  input = PathSafety.ensure_regular_file!(input)
  output = PathSafety.ensure_safe_output_path!(output).to_s
  ensure_jpeg_output!(output)

  input_format = normalized_ext(input)
  unless DIRECT_INPUTS.include?(input_format)
    raise UnsupportedFormatError, "cjpegli direct input format is unsupported: #{input_format.inspect}"
  end

  quality = validate_quality!(quality)
  chroma_subsampling = validate_chroma_subsampling!(chroma_subsampling, input_format: input_format)
  encode(input: input, output: output, quality: quality, chroma_subsampling: chroma_subsampling, timeout: timeout, input_format: input_format)
end

.encode(input:, output:, quality: DEFAULT_QUALITY, chroma_subsampling: "420", timeout: Runner::DEFAULT_TIMEOUT, input_format: nil) ⇒ Object

Raises:



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# File 'lib/safe_image/jpegli_backend.rb', line 40

def encode(input:, output:, quality: DEFAULT_QUALITY, chroma_subsampling: "420", timeout: Runner::DEFAULT_TIMEOUT, input_format: nil)
  raise UnsupportedFormatError, "cjpegli is not installed" unless available?

  input = PathSafety.ensure_regular_file!(input)
  output_path = PathSafety.ensure_safe_output_path!(output)
  ensure_jpeg_output!(output_path)
  output_path.dirname.mkpath

  input_format ||= normalized_ext(input)
  quality = validate_quality!(quality)
  chroma_subsampling = validate_chroma_subsampling!(chroma_subsampling, input_format: input_format)

  tmp = Tempfile.new([output_path.basename(".*").to_s, ".cjpegli.jpg"], output_path.dirname.to_s)
  tmp_path = Pathname.new(tmp.path)
  tmp.close

  begin
    argv = [
      "cjpegli",
      input.to_s,
      tmp_path.to_s,
      "--quality=#{quality}",
      "--chroma_subsampling=#{chroma_subsampling}"
    ]
    Runner.run!(argv, timeout: timeout, read: [input.to_s], write: [output_path.dirname.to_s])
    raise Error, "cjpegli did not create output" unless tmp_path.file? && File.size(tmp_path).positive?
    FileUtils.mv(tmp_path, output_path)

    # cjpegli works without libvips; fall back to identify for the
    # output dimensions when the native header read is unavailable.
    info = VipsGlue.available? ? Native.probe(output_path.to_s) : ImageMagickBackend.probe(output_path.to_s)
    {
      input_format: input_format,
      output_format: "jpg",
      width: info.fetch(:width),
      height: info.fetch(:height),
      duration_ms: info.fetch(:duration_ms),
      encoder: "cjpegli",
      chroma_subsampling: chroma_subsampling
    }
  ensure
    FileUtils.rm_f(tmp_path)
  end
end

.ensure_jpeg_output!(output) ⇒ Object

Raises:



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# File 'lib/safe_image/jpegli_backend.rb', line 101

def ensure_jpeg_output!(output)
  ext = normalized_ext(output)
  raise UnsupportedFormatError, "cjpegli only outputs jpg/jpeg, got #{ext.inspect}" unless ext == "jpg"
end

.normalized_ext(path) ⇒ Object 



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# File 'lib/safe_image/jpegli_backend.rb', line 106

def normalized_ext(path)
  ext = File.extname(path.to_s).delete_prefix(".").downcase
  ext == "jpeg" ? "jpg" : ext
end

.suitable_direct_input?(input) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/safe_image/jpegli_backend.rb', line 19

def suitable_direct_input?(input)
  DIRECT_INPUTS.include?(normalized_ext(input))
end

.validate_chroma_subsampling!(value, input_format: nil) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/safe_image/jpegli_backend.rb', line 92

def validate_chroma_subsampling!(value, input_format: nil)
  value = :auto if value.nil?
  value = "444" if value.to_sym == :auto && input_format.to_s == "png"
  value = "420" if value.to_sym == :auto
  value = value.to_s
  raise ArgumentError, "chroma_subsampling must be one of #{CHROMA_SUBSAMPLING.join(", ")}" unless CHROMA_SUBSAMPLING.include?(value)
  value
end

.validate_quality!(quality) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/safe_image/jpegli_backend.rb', line 85

def validate_quality!(quality)
  quality = DEFAULT_QUALITY if quality.nil?
  quality = Integer(quality)
  raise ArgumentError, "quality must be 1..100" unless (1..100).cover?(quality)
  quality
end