Class: Morandi::VipsImageProcessor

Inherits:
Object
  • Object
show all
Defined in:
lib/morandi/vips_image_processor.rb

Overview

An alternative to ImageProcessor which is based on libvips for concurrent and less memory-intensive processing

Constant Summary collapse

RGB_LUMINANCE_EXTRACTION_FACTORS =

Colour filter related constants

[0.3086, 0.6094, 0.0820].freeze
SEPIA_MODIFIER = 
[25, 5, -25].freeze
BLUETONE_MODIFIER = 
[-10, 5, 25].freeze
COLOUR_FILTER_MODIFIERS = 
{
  'sepia' => SEPIA_MODIFIER,
  'bluetone' => BLUETONE_MODIFIER
}.freeze
SUPPORTED_FILTERS = 
COLOUR_FILTER_MODIFIERS.keys + ['greyscale']

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path, user_options) ⇒ VipsImageProcessor

Returns a new instance of VipsImageProcessor.



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# File 'lib/morandi/vips_image_processor.rb', line 47

def initialize(path, user_options)
  @path = path

  @options = user_options

  @size_limit_on_load_px = @options['output.max']
  @output_width = @options['output.width']
  @output_height = @options['output.height']
end

Class Method Details

.supports?(input, options) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/morandi/vips_image_processor.rb', line 21

def self.supports?(input, options)
  return false unless input.is_a?(String)
  return false if options['brighten'].to_f != 0
  return false if options['contrast'].to_f != 0
  return false if options['sharpen'].to_f != 0
  return false if options['redeye']&.any?
  return false if options['border-style']
  return false if options['background-style']

  true
end

.with_global_options(cache_max:, concurrency:) ⇒ Object

Vips options are global, this method sets them for yielding, then restores to original



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# File 'lib/morandi/vips_image_processor.rb', line 34

def self.with_global_options(cache_max:, concurrency:)
  previous_cache_max = Vips.cache_max
  previous_concurrency = Vips.concurrency

  Vips.cache_set_max(cache_max)
  Vips.concurrency_set(concurrency)

  yield
ensure
  Vips.cache_set_max(previous_cache_max)
  Vips.concurrency_set(previous_concurrency)
end

Instance Method Details

#process! ⇒ Object 



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# File 'lib/morandi/vips_image_processor.rb', line 57

def process!
  source_file_path = Morandi::SrgbConversion.perform(@path) || @path
  begin
    @img = Vips::Image.new_from_file(source_file_path)
  rescue Vips::Error => e
    # Match the known errors
    raise UnknownTypeError if /is not a known file format/.match?(e.message)
    raise CorruptImageError if /Premature end of JPEG file/.match?(e.message)

    # Re-raise generic Error when unknown
    raise Error, e.message
  end
  if @size_limit_on_load_px
    @scale = @size_limit_on_load_px.to_f / [@img.width, @img.height].max
    @img = @img.resize(@scale) if not_equal_to_one(@scale)
  else
    @scale = 1.0
  end

  apply_gamma!
  apply_rotate!
  apply_crop!
  apply_filters!

  if @options['output.limit'] && @output_width && @output_height
    scale_factor = [@output_width, @output_height].max.to_f / [@img.width, @img.height].max
    @img = @img.resize(scale_factor) if scale_factor < 1.0
  end

  strip_alpha!
  ensure_srgb!
end

#write_to_jpeg(target_path, quality = nil) ⇒ Object 



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# File 'lib/morandi/vips_image_processor.rb', line 94

def write_to_jpeg(target_path, quality = nil)
  process!

  quality ||= @options.fetch('quality', 97)

  target_path_jpg = "#{target_path}.jpg" # Vips chooses format based on file extension, this ensures jpg
  @img.write_to_file(target_path_jpg, Q: quality)
  FileUtils.mv(target_path_jpg, target_path)
end

#write_to_png(_write_to, _orientation = :any) ⇒ Object 



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# File 'lib/morandi/vips_image_processor.rb', line 90

def write_to_png(_write_to, _orientation = :any)
  raise 'not implemented'
end