imageblur.rb

class Image
  attr_accessor :array

  def initialize(array)
    @array = array
    @new_array = @array.map {|e| Array.new(e.size) }
  end

  def blur
    @array.each_with_index do |row,x|
      row.each_with_index do |cell,y| 
        last_x_pixel = row.size - 1
        last_y_pixel = @array.size - 1
        if @array[x][y] == 1 
          @new_array[x][y] ||= 1
          @new_array[x-1][y] = 1 if x != 0
          @new_array[x][y-1] = 1 if y != 0
          @new_array[x][y+1] = 1 if y != last_y_pixel
          @new_array[x+1][y] = 1 if x != last_x_pixel
        else
          @new_array[x][y] ||= @array[x][y]
        end 
      end
    end

    def blur(n)
      @array.each_with_index do |row,x|
        row.each_with_index do |cell,y| 
          last_x_pixel = row.size - 1
          last_y_pixel = @array.size - 1
          if @array[x][y] == 1 
            @new_array[x][y] ||= 1
            @new_array[x-n][y] = 1 if x != 0
            @new_array[x][y-n] = 1 if y != 0
            @new_array[x][y+n] = 1 if y != last_y_pixel
            @new_array[x+n][y] = 1 if x != last_x_pixel
          else
            @new_array[x][y] ||= @array[x][y]
          end 
        end
      end
      return Image.new(@new_array)
    end

    def square(x,y,radius)
      #puts step(x,y,radius,radius).inspect
      #puts step(x,y,-radius,-radius).inspect
      #puts step(x,y,+radius,-radius).inspect
      #puts step(x,y,-radius,+radius).inspect

      walk(*step(x,y,-radius,-radius), *step(x,y,+radius,-radius)) + 
        [
          [0,1],step(x,y,-radius),[0,3],
          [4,1],step(x,y,+radius),[4,3],
          [0,4],[1,4],step(x,y,0,+radius),[3,4],[4,4]
      ]
    end

    def walk(x,y,x2,y2)
      delta_x = x2 - x
      delta_y = y2 - x

      result = []
      for i in x..x2
        for j in (y..y2)
          result << [i,j]
        end
      end

      return result

    end

    def step(x,y,delta_x=0,delta_y=0)
      last_x_pixel = @array.first.size - 1
      last_y_pixel = @array.size - 1

      x2 = x+delta_x
      y2 = y+delta_y

      [x2,y2] if x2 <= last_x_pixel && y2 <= last_y_pixel
    end

  end

  def output_image
    @array.each do |i|
      puts i.join("")
    end
  end
end

image = Image.new([
  [0, 0, 0, 0],
  [0, 0, 1, 0],
  [0, 0, 0, 0],
  [1, 1, 0, 0]
])
image.blur

imageblur2_spec.rb

require 'rspec'
require_relative 'imageblur'

describe Image do
  describe '#blur' do
    it 'adds a rectangle replaceing cells content with 1 and with radius 2' do
      image = Image.new([
        [0, 0, 0, 0, 0],
        [0, 0, 0, 0, 0],
        [0, 0, 1, 0, 0],
        [0, 0, 0, 0, 0],
        [0, 0, 0, 0, 0]
      ])

      new_image = Image.new([
        [0, 0, 1, 0, 0],
        [0, 0, 0, 0, 0],
        [1, 0, 1, 0, 1],
        [0, 0, 0, 0, 0],
        [0, 0, 1, 0, 0]
      ])

      expect(image.blur(2).array).to eql(new_image.array)
    end

    describe '#square' do
      it 'returns the cell coordenates of the square' do
        image = Image.new([
          [0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0],
          [0, 0, 1, 0, 0],
          [0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0]
        ])

        square = [
          [0,0],[1,0],[2,0],[3,0],[4,0],
          [0,1],[0,2],[0,3],
          [4,1],[4,2],[4,3],
          [0,4],[1,4],[2,4],[3,4],[4,4]
        ]

        expect(image.square(2,2,2)).to eq(square)

      end
    end

    describe '#step' do
      it 'returns the next cell on the right' do
        cell = Image.new([
          [0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0],
          [0, 0, 1, 0, 0],
          [0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0]
        ]).step(2,2,1)

        expect(cell).to eq([3,2])

      end

      context 'when you arrive the limit' do
        it 'returns 3  cells on the right' do
          cell = Image.new([
            [0, 0, 0, 0, 0],
            [0, 0, 0, 0, 0],
            [0, 0, 1, 0, 0],
            [0, 0, 0, 0, 0],
            [0, 0, 0, 0, 0]
          ]).step(2,2,3)

          expect(cell).to eq(nil)

        end
      end
    end

    describe '#walk' do
      it 'walks in straight line' do
        path = Image.new([
          [0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0],
          [0, 0, 1, 0, 0],
          [0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0]
        ]).walk(2,2,4,2)

        expect(path).to eq([[2,2],[3,2],[4,2]])

      end
      it 'walks in another straight line' do
        path = Image.new([
          [0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0],
          [0, 0, 1, 0, 0],
          [0, 0, 0, 0, 0],
          [0, 0, 0, 0, 0]
        ]).walk(0,0,4,0)

        expect(path).to eq([[0,0],[1,0],[2,0],[3,0],[4,0]])

      end
    end

  end
end

imageblur_spec.rb

require 'rspec'
require_relative 'imageblur'

describe Image do
  describe 'output_image' do

    it 'returns the correct output on output_image' do
      image = Image.new([
        [0, 0, 0, 0],
        [0, 1, 0, 0],
        [0, 0, 0, 1],
        [0, 0, 0, 0]
      ])

      output = "0100\n1111\n0111\n0001\n"
      expect { image.output_image }.to output(output).to_stdout
    end
  end

  describe 'blur' do
    it 'adds 1 around an array with a 1 on a single cell' do
      image = Image.new([
        [0, 0, 0, 0],
        [0, 1, 0, 0],
        [0, 0, 0, 0],
        [0, 0, 0, 0]
      ])

      new_image = Image.new([
        [0, 1, 0, 0],
        [1, 1, 1, 0],
        [0, 1, 0, 0],
        [0, 0, 0, 0]
      ])

      expect(image.blur.array).to eql(new_image.array)
    end

    it 'adds 1 to a border cell'

  end
end