autocrop, colorize, solid color

chunky_png.rb

# Usage:
#
#   image1 = ChunkyPNG::Image.from_file('vase.png')
#   image1.colorfy!(:color => "ff0000")
#   image1.save 'changed_red.png'
#
#   image2 = ChunkyPNG::Image.from_file('vase.png')
#   image2.colorfy!(:color => "ff0000", :solid => true)
#   image2.save 'only_red.png'
#
#
# @author Margus Pärt
# @version 24.11.2011


module ChunkyPNG

  module Color
    # Replace color with choosed color, depending on options
    # 
    # 
    # Options: 
    #   => string|Color :color new color
    #   => boolean :solid if set to solid, only orginal picture alpha is 
    def colorfy(pixel, options) 
      n = ChunkyPNG.Color(options[:color])
      
      if options[:solid]
        r = r(n)
        g = g(n)
        b = b(n)
      else
        gs = grayscale_teint(pixel)
        gf = gs / 255.0
        r = gf * r(n)
        g = gf * g(n)
        b = gf * b(n)
      end
      

      ChunkyPNG::Color::rgba(r.to_i, g.to_i, b.to_i, a(pixel))
    end

  end

  class Canvas
    
    
    # Replace canvas colors with one color level
    #
    # Options: 
    #   => :color
    #   => :solid
    def colorfy!(options = {})
      pixels.map! { |pixel| Color.colorfy(pixel, options) }
    end
    
    # Get pixel addresses of color
    #
    # @arg int|string With color ff0000 format
    # @returns array [[pixel1_x, pixel1_y], [pixel2_x, pixel2_y]]
    def get_color_pixel_cordinates(c)
      c = c.downcase
      cords = []
      # get_pixel, width and height are Canvas methods
      for i in 0...width
        for j in 0...height
          cords << [i,j] if (Color.to_hex(get_pixel(i, j), false) == "##{c}")
        end
      end
      cords
    end  
    
    
    # Autocrop transparent pixels
    def autocrop!
      # mark where pixel found (relative to point 0, 0)
      e = {:top=>false, :bottom=>false, :left=>false, :right=>false}
      
      # find real picture cordinates (exclude transparent)
      for x in 0...width
        for y in 0...height
          # found color
          if 254 < Color.a(get_pixel(x, y))
            # mark it not to be cropped
            e[:top] = y if not e[:top] or y < e[:top]
            e[:bottom] = y if not e[:bottom] or y > e[:bottom]
            e[:left] = x if not e[:left] or x < e[:left]
            e[:right] = x if not e[:right] or x > e[:right]  
          end
        end
      end
      
      # crooooop
      crop!(e[:left], e[:top], e[:right]-e[:left], e[:bottom]-e[:top])      
    end
    
  
    
  end

end