Class: JekyllImgFlow::Providers::Libvips

Inherits:
BaseProvider show all
Defined in:
lib/jekyll-imgflow/providers/libvips.rb

Overview

Libvips provider implementation using the standardized tag interface

Constant Summary

Constants inherited from BaseProvider

BaseProvider::KNOWN_OPERATIONS, BaseProvider::SMARTCROP_POSITIONS

Instance Attribute Summary

Attributes inherited from BaseProvider

#config

Instance Method Summary collapse

Methods inherited from BaseProvider

#add_watermark, #alpha_opacity=, #check_http_service, #convert_format, #crop, #encode_file_url, #format, #initialize, #opacity, #operations, #optimize, provider_name, #quality, #quality=, #reset_operations, #resize, #supports_operation?, supports_operation?, unsupported_operations, #watermark

Constructor Details

This class inherits a constructor from JekyllImgFlow::Providers::BaseProvider

Instance Method Details

#apply_watermark_alpha(base_path, input_path, commands) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 99

def apply_watermark_alpha(base_path, input_path, commands)
  alpha_op = @operations.find { |op| op[:type] == :alpha_opacity }
  return [base_path, commands] unless alpha_op

  alpha_temp = input_path.gsub(/\.[^.]+$/, ".tmp_alpha.jpg")
  [alpha_temp, commands << build_alpha_command(base_path, alpha_temp)]
end

#available? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 11

def available?
  # Check if vips CLI is available
  _, _, status = Open3.capture3("which", "vips")
  status.success?
end

#build_alpha_command(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 170

def build_alpha_command(input_path, output_path)
  alpha_op = @operations.find { |op| op[:type] == :alpha_opacity }
  opacity = alpha_op[:opacity]
  alpha_value = opacity.round(2)

  # vips linear multiplies alpha band: "1 1 1 alpha" scales alpha
  ["vips", "linear", input_path, output_path,
   "1 1 1 #{alpha_value}", "0"]
end

#build_alpha_pipeline(input_path, output_path, has_crop, has_resize) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 74

def build_alpha_pipeline(input_path, output_path, has_crop, has_resize)
  temp_path = input_path.gsub(/\.[^.]+$/, ".tmp_base.jpg")
  commands, base_path = build_base_pipeline(input_path, temp_path, has_crop, has_resize)
  commands << build_alpha_command(base_path, output_path)
  commands << [:cleanup, temp_path] unless base_path == input_path
  commands
end

#build_base_pipeline(input_path, temp_path, has_crop, has_resize) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 91

def build_base_pipeline(input_path, temp_path, has_crop, has_resize)
  return [build_sequential_crop_resize(input_path, temp_path), temp_path] if has_crop && has_resize
  return [[build_resize_command(input_path, temp_path)], temp_path] if has_resize
  return [[build_crop_command(input_path, temp_path)], temp_path] if has_crop

  [[], input_path]
end

#build_composite_commands(base_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 112

def build_composite_commands(base_path, output_path)
  wm_op = @operations.find { |op| op[:type] == :watermark }
  watermark_path = wm_op[:watermark_path]
  position = wm_op[:options][:position]
  opacity = wm_op[:options][:opacity]

  if opacity && opacity < 1.0
    wm_temp = watermark_path.gsub(/\.[^.]+$/, ".tmp_wm.png")
    alpha_value = opacity
    # Step 1: Apply alpha to watermark
    alpha_cmd = ["vips", "linear", watermark_path,
                 "#{wm_temp}[alpha]", "1 1 1 #{alpha_value}", "0"]
    # Step 2: Composite
    xy_args = position_to_vips_xy(position, base_path, watermark_path)
    composite_cmd = ["vips", "composite2", base_path, wm_temp,
                     build_format_spec(output_path), "over"] + xy_args
    # Step 3: Cleanup wm_temp
    [alpha_cmd, composite_cmd, [:cleanup, wm_temp]]
  else
    xy_args = position_to_vips_xy(position, base_path, watermark_path)
    [["vips", "composite2", base_path, watermark_path,
      build_format_spec(output_path), "over"] + xy_args]
  end
end

#build_copy_command(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 275

def build_copy_command(input_path, output_path)
  format_spec = build_format_spec(output_path)
  # For SVGs, `vips copy` rasterizes at intrinsic size (potentially
  # huge). Use thumbnail with a large cap to bound the render safely.
  return ["vips", "thumbnail", input_path, format_spec, "2000"] if svg?(input_path)

  # vips copy input.jpg output.jpg[format]
  ["vips", "copy", input_path, format_spec]
end

#build_crop_command(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 218

def build_crop_command(input_path, output_path)
  crop_op = @operations.find { |op| op[:type] == :crop }
  opts = crop_op[:options] || {}
  params = crop_op[:params] || {}
  keep = opts[:keep] || params[:keep] || params[:position]
  return build_smartcrop_command(crop_op, opts, keep, input_path, output_path) if smartcrop?(crop_op, keep)

  build_extract_command(crop_op, opts, input_path, output_path)
end

#build_extract_command(crop_op, opts, input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 240

def build_extract_command(crop_op, opts, input_path, output_path)
  ratio = crop_op[:ratio]
  x = ratio ? opts[:calculated_x] : (opts[:x] || 0)
  y = ratio ? opts[:calculated_y] : (opts[:y] || 0)
  width = ratio ? opts[:calculated_width] : opts[:width]
  height = ratio ? opts[:calculated_height] : opts[:height]
  ["vips", "extract_area", input_path, output_path,
   x.to_s, y.to_s, width.to_s, height.to_s]
end

#build_format_spec(output_path) ⇒ Object

Build vips output specification with format and quality. Returns a raw string — no shell quoting needed since commands are executed via Open3.capture3 array form (no shell).



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 288

def build_format_spec(output_path)
  # Build vips output specification with format and quality
  format_op = @operations.find { |op| op[:type] == :format }
  quality_op = @operations.find { |op| op[:type] == :quality }

  # Simple case: no format/quality operations
  return output_path unless format_op || quality_op

  # Extract format from operation or output path
  ext = format_op ? format_op[:format] : File.extname(output_path).delete(".")
  base = output_path.gsub(/\.[^.]+$/, "")

  # Build format spec with quality if present
  if quality_op
    quality = quality_op[:quality]
    "#{base}.#{ext}[Q=#{quality}]"
  else
    "#{base}.#{ext}"
  end
end

#build_resize_command(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 197

def build_resize_command(input_path, output_path)
  resize_op = @operations.find { |op| op[:type] == :resize }
  format_spec = build_format_spec(output_path)
  width = resize_op[:width]
  height = resize_op[:height]

  # Use `vips thumbnail` for all resize operations. thumbnail is the
  # recommended high-level resize API — it uses shrink-on-load for
  # JPEGs (efficient), handles SVGs safely by bounding render size
  # during load, and supports all image formats.
  # See https://www.libvips.org/API/current/func.thumbnail.html
  if width && height
    # Both dimensions: thumbnail to width, cap height, crop to fill
    ["vips", "thumbnail", input_path, format_spec,
     width.to_s, "--height=#{height}", "--crop=attention"]
  else
    # Only width: thumbnail maintains aspect ratio
    ["vips", "thumbnail", input_path, format_spec, width.to_s]
  end
end

#build_sequential_crop_resize(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 180

def build_sequential_crop_resize(input_path, output_path)
  if svg?(input_path)
    # SVG: use thumbnail with --crop to do crop+resize in one step
    resize_op = @operations.find { |op| op[:type] == :resize }
    format_spec = build_format_spec(output_path)
    width = resize_op[:width]
    height = resize_op[:height]
    [["vips", "thumbnail", input_path, format_spec,
      width.to_s, "--height=#{height}", "--crop=attention"]]
  else
    temp_path = input_path.gsub(/\.[^.]+$/, ".tmp_crop.jpg")
    [build_crop_command(input_path, temp_path),
     build_resize_command(temp_path, output_path),
     [:cleanup, temp_path]]
  end
end

#build_smartcrop_command(_crop_op, opts, keep, input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 232

def build_smartcrop_command(_crop_op, opts, keep, input_path, output_path)
  interestingness = %w[center centre].include?(keep.to_s) ? "centre" : keep.to_s
  interestingness = "attention" unless %w[entropy centre].include?(interestingness)
  ["vips", "smartcrop", input_path, output_path,
   opts[:calculated_width].to_s, opts[:calculated_height].to_s,
   "--interesting=#{interestingness}"]
end

#build_svg_crop_pipeline(input_path, output_path) ⇒ Object

SVG crop: use vips thumbnail with --crop to crop during thumbnailing. This avoids the coordinate mismatch that occurs when rasterizing at a different size than the SVG's viewBox (which caused "bad extract area"). thumbnail --crop uses smartcrop (attention/entropy/centre) to select the most interesting region — this is the correct behavior for SVGs since they have no fixed pixel dimensions.



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 256

def build_svg_crop_pipeline(input_path, output_path)
  crop_op = @operations.find { |op| op[:type] == :crop }
  opts = crop_op[:options] || {}
  crop_width = crop_op[:ratio] ? opts[:calculated_width] : (opts[:width] || 1000)
  crop_height = crop_op[:ratio] ? opts[:calculated_height] : (opts[:height] || 1000)
  format_spec = build_format_spec(output_path)

  keep = opts[:keep] || crop_op[:params]&.[](:keep) || crop_op[:params]&.[](:position)
  interestingness = case keep.to_s
                    when "entropy" then "entropy"
                    when "center", "centre" then "centre"
                    else "attention"
                    end

  [["vips", "thumbnail", input_path, format_spec,
    crop_width.to_s, "--height=#{crop_height}",
    "--crop=#{interestingness}"]]
end

#build_vips_command(input_path, output_path) ⇒ Object

Convenience wrapper for backward compatibility with tests. Returns the commands joined as a debug string.



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 64

def build_vips_command(input_path, output_path)
  build_vips_commands(input_path, output_path).map do |cmd|
    if cmd.is_a?(Array) && cmd.first == :cleanup
      "rm -f #{cmd[1]}"
    else
      cmd.join(" ")
    end
  end.join(" && ")
end

#build_vips_commands(input_path, output_path) ⇒ Object

Build all vips commands as an array of command arrays. Each sub-array is passed directly to Open3.capture3 (no shell). Returns Array[Array[String]].



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 33

def build_vips_commands(input_path, output_path)
  flags = operation_flags
  operation_builder = select_operation_builder(flags)
  operation_builder.call(input_path, output_path)
end

#build_watermark_pipeline(input_path, output_path, has_crop, has_resize) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 82

def build_watermark_pipeline(input_path, output_path, has_crop, has_resize)
  temp_path = input_path.gsub(/\.[^.]+$/, ".tmp_base.jpg")
  commands, base_path = build_base_pipeline(input_path, temp_path, has_crop, has_resize)
  base_path, commands = apply_watermark_alpha(base_path, input_path, commands)
  commands.concat(build_composite_commands(base_path, output_path))
  cleanup_paths(commands, input_path, temp_path, base_path)
  commands
end

#cleanup_paths(commands, input_path, temp_path, base_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 107

def cleanup_paths(commands, input_path, temp_path, base_path)
  temp_files = [temp_path, base_path == input_path ? nil : base_path].compact
  temp_files.each { |file| commands << [:cleanup, file] }
end

#crop_commands(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 58

def crop_commands(input_path, output_path)
  svg?(input_path) ? build_svg_crop_pipeline(input_path, output_path) : [build_crop_command(input_path, output_path)]
end

#execute(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 17

def execute(input_path, output_path)
  return if @operations.empty?

  # Build and execute vips commands (array form, no shell).
  # Cleanup markers ([:cleanup, path]) are handled by execute_command.
  commands = build_vips_commands(input_path, output_path)
  commands.each { |cmd_array| execute_command(cmd_array) }

  output_path
ensure
  reset_operations
end

#execute_command(command) ⇒ Object

Execute a command array via Open3.capture3 (no shell invocation).

Parameters:

  • command (Array<String>) —

    Command and arguments as array



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 311

def execute_command(command)
  if command.is_a?(Array) && command.first == :cleanup
    FileUtils.rm_f(command[1])
    return
  end

  Jekyll.logger.debug "LibVips command: #{command.join(' ')}"

  # Execute command array directly (no shell)
  # nosemgrep: ruby.lang.security.dangerous-exec.dangerous-exec -- command is an argument array; no shell is invoked.
  stdout, stderr, status = Open3.capture3(*command)
  output = "#{stdout}#{stderr}"
  success = status.success?

  unless success
    cmd_str = command.join(" ")
    # Filter out expected warnings and only log real errors
    raise "LibVips command failed: #{cmd_str}\nError: #{output}" unless output.include?("same file") || output.include?("VipsForeignSave")

    Jekyll.logger.warn "LibVips warning: #{output.strip}"
    return output.strip # Continue despite warnings

  end

  output.strip
end

#operation_flags ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 49

def operation_flags
  {
    crop: @operations.any? { |op| op[:type] == :crop },
    resize: @operations.any? { |op| op[:type] == :resize },
    watermark: @operations.any? { |op| op[:type] == :watermark },
    alpha: @operations.any? { |op| op[:type] == :alpha_opacity }
  }
end

#position_to_vips_xy(position, _base_path, watermark_path) ⇒ Object

Return x/y arguments as an array of strings (no shell substitution). Pre-computes image dimensions via vips header in Ruby.



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 139

def position_to_vips_xy(position, _base_path, watermark_path)
  case position.to_s
  when "northeast", "top-right"
    width = vips_image_dimension(watermark_path, "width")
    ["--x", width.to_s, "--y", "0"]
  when "southwest", "bottom-left"
    height = vips_image_dimension(watermark_path, "height")
    ["--x", "0", "--y", height.to_s]
  when "southeast", "bottom-right"
    width = vips_image_dimension(watermark_path, "width")
    height = vips_image_dimension(watermark_path, "height")
    ["--x", width.to_s, "--y", height.to_s]
  else
    ["--x", "0", "--y", "0"] # northwest, top-left, center, centre, and default
  end
end

#select_operation_builder(flags) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 39

def select_operation_builder(flags)
  return ->(input, output) { build_watermark_pipeline(input, output, flags[:crop], flags[:resize]) } if flags[:watermark]
  return ->(input, output) { build_alpha_pipeline(input, output, flags[:crop], flags[:resize]) } if flags[:alpha]
  return ->(input, output) { build_sequential_crop_resize(input, output) } if flags[:crop] && flags[:resize]
  return ->(input, output) { [build_resize_command(input, output)] } if flags[:resize]
  return ->(input, output) { crop_commands(input, output) } if flags[:crop]

  ->(input, output) { [build_copy_command(input, output)] }
end

#smartcrop?(crop_op, keep) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 228

def smartcrop?(crop_op, keep)
  crop_op[:ratio] && keep && %w[attention entropy center centre].include?(keep.to_s)
end

#vips_image_dimension(image_path, field) ⇒ Object

Get an image dimension (width or height) using vips header. Returns integer or 0 if vips is unavailable.



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 158

def vips_image_dimension(image_path, field)
  return 0 unless %w[width height].include?(field)

  # nosemgrep: ruby.lang.security.dangerous-exec.dangerous-exec -- Open3 receives an argument array and field is allowlisted.
  stdout, _, status = Open3.capture3("vips", "header", image_path, field)
  return 0 unless status.success?

  stdout.strip.to_i
rescue StandardError
  0
end