Class: Escpos::ImageProcessors::MiniMagick

Inherits:
Base
  • Object
show all
Defined in:
lib/escpos/image_processors/mini_magick.rb

Instance Attribute Summary

Attributes inherited from Base

#image, #options

Instance Method Summary collapse

Methods inherited from Base

#assert_dimensions_multiple_of_8!

Constructor Details

#initialize(image_or_path, options = {}) ⇒ MiniMagick

Returns a new instance of MiniMagick.



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# File 'lib/escpos/image_processors/mini_magick.rb', line 7

def initialize(image_or_path, options = {})
  require_mini_magick!

  @image = begin
    if image_or_path.is_a?(::MiniMagick::Image)
      image_or_path
    elsif image_or_path.is_a?(String)
      ::MiniMagick::Image.open(image_or_path)
    else
      raise InputNotSupported
    end
  end

  super
end

Instance Method Details

#assert_options! ⇒ Object 



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# File 'lib/escpos/image_processors/mini_magick.rb', line 34

def assert_options!
  assert_dimensions_multiple_of_8!
end

#get_pixel(x, y) ⇒ Object 



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# File 'lib/escpos/image_processors/mini_magick.rb', line 23

def get_pixel(x, y)
  @pixels ||= image.get_pixels

  r, g, b =
    @pixels[y][x][0],
    @pixels[y][x][1],
    @pixels[y][x][2]

  (r + b + g) / 3
end

#process! ⇒ Object 



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# File 'lib/escpos/image_processors/mini_magick.rb', line 48

def process!
  if options.fetch(:compose_alpha, false)
    image.combine_options do |c|
      bg_r, bg_g, bg_b =
        options.fetch(:compose_alpha_bg_r, 255),
        options.fetch(:compose_alpha_bg_g, 255),
        options.fetch(:compose_alpha_bg_b, 255)
      c.background "rgb(#{bg_r},#{bg_g},#{bg_b})"
      c.flatten
    end
  end

  # Get the first image out of animated gifs
  image.collapse!

  # Optimise more actions to single call
  image.combine_options do |c|
    c.rotate options.fetch(:rotate) if options.has_key?(:rotate)
    c.resize options.fetch(:resize) if options.has_key?(:resize)

    c.grayscale('Rec709Luma') if options.fetch(:grayscale, false)

    if options.fetch(:dither, false)
      c.monochrome '+dither'
      # dither the image with FloydSteinberg algoritm for better results
      c.dither 'FloydSteinberg'
    end
  end

  # Limit the extent of the image to nice round numbers
  if options.fetch(:extent, false)
    image.extent "#{(image.width/8.0).round*8}x#{(image.height/8.0).round*8}"
  end
end

#require_mini_magick! ⇒ Object

MiniMagick gem is not required intentionally This makes the gem more lightweight by making dependencies optional and based on chosen image processor



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# File 'lib/escpos/image_processors/mini_magick.rb', line 41

def require_mini_magick!
  return if defined?(::MiniMagick)
  require "mini_magick"
  rescue LoadError => e
    raise DependencyNotInstalled.new("mini_magick")
end