Class: Browsery::DiffImage

Inherits:
Object
  • Object
show all
Defined in:
lib/browsery/diff_image.rb

Instance Method Summary collapse

Constructor Details

#initialize(base_image, new_image) ⇒ DiffImage

Returns a new instance of DiffImage.



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# File 'lib/browsery/diff_image.rb', line 7

def initialize(base_image, new_image)
  @base_image = ChunkyPNG::Image.from_file(base_image)
  @new_image = ChunkyPNG::Image.from_file(new_image)
  @diff_image = ChunkyPNG::Image.new(@base_image.width, @new_image.width, BLACK)
end

Instance Method Details

#calculate_changes ⇒ Object 



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# File 'lib/browsery/diff_image.rb', line 13

def calculate_changes
  diff = []

  @base_image.height.times do |y|
    @base_image.row(y).each_with_index do |pixel, x|
      unless pixel == @new_image[x,y]
        score = Math.sqrt(
          (r(@new_image[x,y]) - r(pixel)) ** 2 +
          (g(@new_image[x,y]) - g(pixel)) ** 2 +
          (b(@new_image[x,y]) - b(pixel)) ** 2
        ) / Math.sqrt(MAX ** 2 * 3)
        diff << score
      end
      @diff_image[x,y] = rgb(
        r(pixel) + r(@new_image[x,y]) - 2 * [r(pixel), r(@new_image[x,y])].min,
        g(pixel) + g(@new_image[x,y]) - 2 * [g(pixel), g(@new_image[x,y])].min,
        b(pixel) + b(@new_image[x,y]) - 2 * [b(pixel), b(@new_image[x,y])].min
      )
    end
  end

  total_pixels = @base_image.pixels.length
  diff_percentage = diff.empty? ? 0 : diff.inject {|sum, value| sum + value} / total_pixels
  puts "pixels (total):     #{total_pixels}"
  puts "pixels changed:     #{diff.length}"
  puts "image changed (%):  #{diff_percentage * 100} %"

  diff_percentage
end

#save_diff(diff_image) ⇒ Object 



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# File 'lib/browsery/diff_image.rb', line 43

def save_diff(diff_image)
  @diff_image.save(diff_image)
end