Mercurial > lasercutter

     1 class Graster

     2   class Image

     3     PROPS = [:filename,:size,:pixels]

     4 

     5     def initialize(props)

     6       PROPS.each do |p|

     7         raise "required image property :#{p} missing" unless props[p]

     8         instance_variable_set "@#{p}", props[p]

     9       end

    10     end

    11 

    12     PROPS.each{|p| attr_reader p }

    13 

    14     def self.from_file pathname

    15       raise "file not found #{pathname}" unless File.exist? pathname

    16       img = Magick::Image.read(pathname)

    17       raise "bad image data in #{pathname}" unless img = img[0]

    18       new :filename => File.basename(pathname),

    19           :size => [img.columns,img.rows],

    20           :pixels => img.export_pixels(0,0,img.columns,img.rows,"I")

    21     end

    22 

    23     # get pixel(s) from x,y coords

    24     # 0,0 is bottom,left

    25     # image[x,y] => pixel at x,y

    26     # image[y] => row at y

    27     def [] y, x=nil

    28       if x

    29         @pixels[(@size[1]-y)*@size[0]+x]

    30       else

    31         @pixels[(@size[1]-y)*@size[0],@size[0]]

    32       end

    33     end

    34 

    35     def each_row &block

    36       @pixels.chars.each_slice(@size[0]).each_with_index &block

    37     end

    38 

    39     # "encode" a float 0..1 to a pixel

    40     def self.f_to_pix f

    41       (f*65535).round

    42     end

    43 

    44     # "decode" an encoded pixel to a float 0..1

    45     def self.pix_to_f pix

    46       pix/65535.0

    47     end

    48 

    49 

    50     # convert bitmap data to spans (or runs) of contiguous pixels

    51     # also invert the Y axis

    52     def build_spans on_range

    53       # TODO: rewrite in terms of each_row

    54       @spans = Array.new @size[1]

    55 

    56       @size[1].times do |y|

    57         spans = []

    58         left = (@size[1]-y-1)*@size[0]

    59         start = nil

    60 

    61         @size[0].times do |x|

    62           d = on_range.include?(@pixels[left+x])

    63 

    64           if !start && d

    65             start = x

    66           elsif start && !d

    67             spans << [start, x]

    68             start = nil

    69           end

    70         end

    71 

    72         spans << [start, @size[0]] if start

    73         @spans[y] = spans

    74       end

    75     end

    76 

    77     attr_reader :spans

    78 

    79     def hash

    80       [@pixels,@width,@height].hash

    81     end

    82   end

    83 end
author	Robert McIntyre <rlm@mit.edu>
date	Tue, 24 Aug 2010 19:06:45 -0400
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