Class: Pixelart::Pixelator

Inherits:
Object
  • Object
show all
Defined in:
lib/pixelart/pixelator.rb

Overview

or use Minifier or such - rename - why? why not?

Instance Method Summary collapse

Constructor Details

#initialize(img, width = 24, height = 24) ⇒ Pixelator

Returns a new instance of Pixelator.

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# File 'lib/pixelart/pixelator.rb', line 6

def initialize( img, width=24, height=24 )
  @img    = img.is_a?( Image ) ? img.image : img  ## "unwrap" if Pixelart::Image
  @width  = width
  @height = height

  ## calculate pixel size / density / resolution
  ##   how many pixels per pixel?
  @xsize, @xoverflow = img.width.divmod( width )
  @ysize, @yoverflow = img.height.divmod( height )

  puts "minify image size from (#{@img.width}x#{@img.height}) to (#{width}x#{height})"
  puts "  pixel size (#{@xsize}x#{@ysize}) - #{@xsize*@ysize} pixel(s) per pixel"
  puts "    overflow x: #{@xoverflow}, y: #{@yoverflow} pixel(s)"    if @xoverflow > 0 || @yoverflow > 0
end

Instance Method Details

#can_pixelate?(threshold: 50) ⇒ Boolean Also known as: pixelate?

Returns:

  • (Boolean)
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# File 'lib/pixelart/pixelator.rb', line 79

def can_pixelate?( threshold: 50 )
  # check if any pixel has NOT a color with a 50% majority?
  count = 0
  @width.times do |x|
    @height.times do |y|
      pixel = pixel( x, y )
      sum         = pixel.values.sum
      color_count = pixel.values[0]

      threshold_count = sum / (100/threshold)
      if color_count < threshold_count
        count += 1
        puts "!! #{color_count} < #{threshold_count} (#{threshold}%)"
        ## todo/check: stor warn in a public errors or warns array - why? why not?
        puts "!! WARN #{count} - pixel (#{x}/#{y}) - no majority (#{threshold}%) color:"
        pp pixel
      end
    end
  end

  count == 0    ## return true if not warnings found
end

#grid(spacing: 10) ⇒ Object

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# File 'lib/pixelart/pixelator.rb', line 22

def grid( spacing: 10 )
  width  = @img.width  + (@width-1)*spacing
  height = @img.height + (@height-1)*spacing

  img = ChunkyPNG::Image.new( width, height, ChunkyPNG::Color::WHITE )

  @img.width.times do |x|
    xpixel = x/@xsize
    @img.height.times do |y|
      ypixel = y/@ysize

      ## clip overflow pixels
      xpixel = @width-1   if xpixel >= @width
      ypixel = @height-1  if ypixel >= @height

      color = @img[x,y]
      img[x + spacing*xpixel,
          y + spacing*ypixel] = color
    end
  end

  Image.new( img.width, img.height, img )  ## wrap in Pixelart::Image - why? why not?
end

#outline ⇒ Object

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# File 'lib/pixelart/pixelator.rb', line 118

def outline
  ## create a two color outline (transparent and non-transparent color)
  img = ChunkyPNG::Image.new( @width, @height )

  @width.times do |x|
    @height.times do |y|
      pixel = pixel( x, y )
      ## calculate pixel count for transparent and non-transparent parts
      ##   note:
      ##     also count all colors with alpha channel < 200 to transparent!!
      transparent_count, color_count = pixel.reduce([0,0]) do |mem, (color,count)|
                                        hsl = Color.to_hsl( color )
                                        ## get alpha channel (transparency) for hsla
                                        ##    0-255 max.
                                        alpha = hsl[3]
                                       if color == 0x00 || alpha < 200
                                          mem[0] += count
                                       else
                                          mem[1] += count
                                       end
                                       mem
                                   end

      print "."
      if transparent_count > 0 && color_count > 0
        print "(#{x}/#{y}=>#{transparent_count}/#{color_count})"
      end

      ## todo/check:
      ##   warn if sum_transparent == sum_color
      ##    or within "threshold" e.g. below 55% or 58% or such - why? why not?
      ##    or add treshold as param to outline?
      color = if transparent_count > color_count
                 0x0
              else
                 0x0000ffff  ## use blue for now
              end

      img[x,y] = color
    end
  end
  print "\n"

  Image.new( img.width, img.height, img )  ## wrap in Pixelart::Image - why? why not?
end

#pixel(x, y) ⇒ Object Also known as: []

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# File 'lib/pixelart/pixelator.rb', line 75

def pixel(x,y)  pixels[x+y*@width]; end

#pixelate ⇒ Object

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# File 'lib/pixelart/pixelator.rb', line 104

def pixelate
  img = ChunkyPNG::Image.new( @width, @height )

  @width.times do |x|
    @height.times do |y|
      pixel = pixel( x, y )
      color = pixel.keys[0]
      img[x,y] = color
    end
  end

  Image.new( img.width, img.height, img )  ## wrap in Pixelart::Image - why? why not?
end

#pixels ⇒ Object

pixels by coordinates (x/y) with color statistics / usage

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# File 'lib/pixelart/pixelator.rb', line 48

def pixels
  @pixels ||= begin
                pixels = []
                @img.width.times do |x|
                  xpixel = x/@xsize
                  @img.height.times do |y|
                    ypixel = y/@ysize

                    ## skip/cut off overflow pixels
                    next if xpixel >= @width || ypixel >= @height

                    color = @img[x,y]
                    colors = pixels[xpixel+ypixel*@width] ||= Hash.new(0)
                    colors[ color ] += 1
                  end
                end

                ## sort pixel colors by usage / count (highest first)
                pixels = pixels.map do |pixel|
                                       pixel.sort do |l,r|
                                                    r[1] <=> l[1]
                                                  end.to_h
                                    end
                pixels
              end
end