Class: Escpos::ImageProcessors::ChunkyPng

Inherits:
Base
  • Object
show all
Defined in:
lib/escpos/image_processors/chunky_png.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 = {}) ⇒ ChunkyPng

Returns a new instance of ChunkyPng.



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

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

  @image = begin
    if image_or_path.is_a?(ChunkyPNG::Image)
      image_or_path
    elsif image_or_path.is_a?(String)
      ChunkyPNG::Image.from_file(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/chunky_png.rb', line 23

def assert_options!
  assert_dimensions_multiple_of_8!
end

#get_pixel(x, y) ⇒ Object 



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# File 'lib/escpos/image_processors/chunky_png.rb', line 37

def get_pixel(x, y)
  px = image.get_pixel x, y
  r, g, b =
    ChunkyPNG::Color.r(px),
    ChunkyPNG::Color.g(px),
    ChunkyPNG::Color.b(px)

  (r + b + g) / 3
end

#process! ⇒ Object 



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# File 'lib/escpos/image_processors/chunky_png.rb', line 47

def process!
  extent = options.fetch(:extent, false)
  compose_alpha = options.fetch(:compose_alpha, false)
  grayscale = options.fetch(:extent, false)

  if extent
    new_width = (image.width / 8.0).round * 8
    new_height = (image.height / 8.0).round * 8
    image.resample_nearest_neighbor!(new_width, new_height)
  end

  return if !compose_alpha && !grayscale

  if compose_alpha
    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)
  end

  0.upto(image.height - 1) do |y|
    0.upto(image.width - 1) do |x|
      px = image.get_pixel(x, y)
      if compose_alpha
        bg_color = ChunkyPNG::Color.rgb(bg_r, bg_g, bg_b)
        px = ChunkyPNG::Color.compose_quick(px, bg_color)
      end
      if grayscale
        px = ChunkyPNG::Color.to_grayscale(px)
      end
      image.set_pixel(x, y, px)
    end
  end
end

#require_chunky_png! ⇒ Object

ChunkyPng 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/chunky_png.rb', line 30

def require_chunky_png!
  return if defined?(::ChunkyPng)
  require "chunky_png"
  rescue LoadError => e
    raise DependencyNotInstalled.new("chunky_png")
end