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::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

#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 151

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.shellescape, output_path.shellescape,
   "\"1 1 1 #{alpha_value}\"", "0"].join(" ")
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 49

def build_alpha_pipeline(input_path, output_path, has_crop, has_resize)
  commands = []
  temp_path = input_path.gsub(/\.[^.]+$/, ".tmp_base.jpg")

  if has_crop && has_resize
    commands << build_sequential_crop_resize(input_path, temp_path)
    base_path = temp_path
  elsif has_resize
    commands << build_resize_command(input_path, temp_path)
    base_path = temp_path
  elsif has_crop
    commands << build_crop_command(input_path, temp_path)
    base_path = temp_path
  else
    base_path = input_path
  end

  commands << build_alpha_command(base_path, output_path)
  commands << "rm -f #{temp_path.shellescape}" unless base_path == input_path
  commands.join(" && ")
end

#build_composite_command(base_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 109

def build_composite_command(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]
  format_spec = build_format_spec(output_path)

  if opacity && opacity < 1.0
    wm_temp = watermark_path.gsub(/\.[^.]+$/, ".tmp_wm.png")
    alpha_value = opacity
    temp_cmd = ["vips", "linear", watermark_path.shellescape,
                "'#{wm_temp}[alpha]'", "\"1 1 1 #{alpha_value}\"", "0"].join(" ")
    full_cmd = ["#{temp_cmd} && vips composite2",
                base_path.shellescape, wm_temp.shellescape,
                format_spec, "over",
                position_to_vips_xy(position, base_path, watermark_path)].join(" ")
    # Add cleanup
    "#{full_cmd} && rm -f #{wm_temp.shellescape}"
  else
    ["vips", "composite2", base_path.shellescape,
     watermark_path.shellescape, format_spec, "over",
     position_to_vips_xy(position, base_path, watermark_path)].join(" ")
  end
end

#build_copy_command(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 243

def build_copy_command(input_path, output_path)
  # vips copy input.jpg output.jpg[format]
  format_spec = build_format_spec(output_path)
  ["vips", "copy", input_path.shellescape, format_spec].join(" ")
end

#build_crop_command(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 203

def build_crop_command(input_path, output_path)
  crop_op = @operations.find { |op| op[:type] == :crop }
  opts = crop_op[:options] || {}
  params = crop_op[:params] || {}

  # Check if we should use smartcrop (when keep parameter is specified)
  # JPT keep options: attention (default), entropy, center
  # Check both options (from CropTag) and params (from OperationProcessor)
  keep = opts[:keep] || params[:keep] || params[:position]

  if crop_op[:ratio] && keep && %w[attention entropy center
                                   centre].include?(keep.to_s)
    # Use libvips smartcrop for intelligent cropping
    crop_width = opts[:calculated_width]
    crop_height = opts[:calculated_height]

    # Map keep parameter to libvips interestingness
    interestingness = case keep.to_s
                      when "entropy" then "entropy"
                      when "center", "centre" then "centre"
                      else "attention" # default
                      end

    # vips smartcrop input.jpg output.jpg width height --interesting=attention
    ["vips", "smartcrop", input_path.shellescape, output_path.shellescape,
     crop_width.to_s, crop_height.to_s,
     "--interesting=#{interestingness}"].join(" ")
  else
    # Use basic extract_area for manual cropping or when no keep parameter
    crop_x = crop_op[:ratio] ? opts[:calculated_x] : (opts[:x] || 0)
    crop_y = crop_op[:ratio] ? opts[:calculated_y] : (opts[:y] || 0)
    crop_width = crop_op[:ratio] ? opts[:calculated_width] : opts[:width]
    crop_height = crop_op[:ratio] ? opts[:calculated_height] : opts[:height]

    # vips extract_area input.jpg output.jpg left top width height
    ["vips", "extract_area", input_path.shellescape, output_path.shellescape,
     crop_x.to_s, crop_y.to_s, crop_width.to_s, crop_height.to_s].join(" ")
  end
end

#build_format_spec(output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 249

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.shellescape 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
  # Use single quotes to preserve bracket syntax (shellescape breaks it)
  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 175

def build_resize_command(input_path, output_path)
  resize_op = @operations.find { |op| op[:type] == :resize }
  resize_data = resize_op[:options] || {}

  if resize_op[:width] && resize_op[:height]
    # Both dimensions specified - use VipsResize with vscale for exact dimensions
    # ResizeTag has already done the calculations, so we use both scale factors
    scale_x = resize_data[:scale_x]
    scale_y = resize_data[:scale_y]
    format_spec = build_format_spec(output_path)

    # Only add vscale if we have both scale factors
    if scale_x && scale_y
      ["vips", "VipsResize", input_path.shellescape, format_spec,
       scale_x.to_s, "--vscale=#{scale_y}"].join(" ")
    else
      # Fallback to scale_x only if scale_y is missing
      ["vips", "VipsResize", input_path.shellescape, format_spec,
       (scale_x || 1.0).to_s].join(" ")
    end
  else
    # Only one dimension - use VipsResize with scale_x (maintain aspect ratio)
    scale_x = resize_data[:scale_x] || 1.0
    format_spec = build_format_spec(output_path)
    ["vips", "VipsResize", input_path.shellescape, format_spec, scale_x.to_s].join(" ")
  end
end

#build_sequential_crop_resize(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 161

def build_sequential_crop_resize(input_path, output_path)
  # Build temp file path for intermediate crop result
  temp_path = input_path.gsub(/\.[^.]+$/, ".tmp_crop.jpg")

  # First command: crop only
  crop_cmd = build_crop_command(input_path, temp_path)

  # Second command: resize + format + quality + alpha (all together)
  resize_cmd = build_resize_command(temp_path, output_path)

  # Combine with && and cleanup temp file
  "#{crop_cmd} && #{resize_cmd} && rm -f #{temp_path.shellescape}"
end

#build_vips_command(input_path, output_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 28

def build_vips_command(input_path, output_path)
  has_crop = @operations.any? { |op| op[:type] == :crop }
  has_resize = @operations.any? { |op| op[:type] == :resize }
  has_watermark = @operations.any? { |op| op[:type] == :watermark }
  has_alpha = @operations.any? { |op| op[:type] == :alpha_opacity }

  if has_watermark
    build_watermark_pipeline(input_path, output_path, has_crop, has_resize)
  elsif has_alpha
    build_alpha_pipeline(input_path, output_path, has_crop, has_resize)
  elsif has_crop && has_resize
    build_sequential_crop_resize(input_path, output_path)
  elsif has_resize
    build_resize_command(input_path, output_path)
  elsif has_crop
    build_crop_command(input_path, output_path)
  else
    build_copy_command(input_path, output_path)
  end
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 71

def build_watermark_pipeline(input_path, output_path, has_crop, has_resize)
  temp_path = input_path.gsub(/\.[^.]+$/, ".tmp_base.jpg")
  final_path = output_path

  commands = []

  # Step 1: Process crop/resize/copy to produce base image
  if has_crop && has_resize
    commands << build_sequential_crop_resize(input_path, temp_path)
    base_path = temp_path
  elsif has_resize
    commands << build_resize_command(input_path, temp_path)
    base_path = temp_path
  elsif has_crop
    commands << build_crop_command(input_path, temp_path)
    base_path = temp_path
  else
    base_path = input_path
  end

  # Step 2: Apply alpha opacity if present (before watermark)
  alpha_op = @operations.find { |op| op[:type] == :alpha_opacity }
  if alpha_op
    alpha_temp = input_path.gsub(/\.[^.]+$/, ".tmp_alpha.jpg")
    commands << build_alpha_command(base_path, alpha_temp)
    base_path = alpha_temp
  end

  # Step 3: Composite watermark over base
  commands << build_composite_command(base_path, final_path)

  # Step 4: Cleanup temp files
  temp_files = [temp_path, base_path == input_path ? nil : base_path].compact
  temp_files.each { |f| commands << "rm -f #{f.shellescape}" }

  commands.join(" && ")
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 single vips command with all operations
  command = build_vips_command(input_path, output_path)
  execute_command(command)

  reset_operations
  output_path
end

#execute_command(command) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 271

def execute_command(command)
  Jekyll.logger.debug "LibVips command: #{command}"

  # Execute command and capture output
  stdout, stderr, status = Open3.capture3(command)
  output = "#{stdout}#{stderr}"
  success = status.success?

  unless success
    # Filter out expected warnings and only log real errors
    raise "LibVips command failed: #{command}\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

#position_to_vips_xy(position, _base_path, watermark_path) ⇒ Object 



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# File 'lib/jekyll-imgflow/providers/libvips.rb', line 134

def position_to_vips_xy(position, _base_path, watermark_path)
  # Get image dimensions to calculate x/y from compass positions
  # vips composite2 uses --x and --y for overlay placement
  case position.to_s
  when "northeast", "top-right"
    # Need watermark width; use shell substitution
    "--x $(vips header #{watermark_path.shellescape} width) --y 0"
  when "southwest", "bottom-left"
    "--x 0 --y $(vips header #{watermark_path.shellescape} height)"
  when "southeast", "bottom-right"
    "--x $(vips header #{watermark_path.shellescape} width) " \
    "--y $(vips header #{watermark_path.shellescape} height)"
  else
    "--x 0 --y 0" # northwest, top-left, center, centre, and default
  end
end