Class: Chico::Bitmapper

Inherits:
Object
  • Object
show all
Defined in:
lib/chico/bitmapper.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data, ico_direntry = nil) ⇒ Bitmapper

Returns a new instance of Bitmapper.



6
7
8
9
 
# File 'lib/chico/bitmapper.rb', line 6

def initialize(data, ico_direntry=nil)
    @data = data
  @ico_direntry = ico_direntry
end

Instance Attribute Details

#pixels ⇒ Object (readonly)

Returns the value of attribute pixels.



4
5
6
 
# File 'lib/chico/bitmapper.rb', line 4

def pixels
  @pixels
end

Instance Method Details

#bitmap ⇒ Object 



11
12
13
14
15
16
17
18
19
 
# File 'lib/chico/bitmapper.rb', line 11

def bitmap
  parse_dib
  @pixels = case @bits_per_pixel
            when 0..8 then bitmap8
            when 24 then bitmap24
            when 32 then bitmap32
            else raise "Unable to handle #{@bits_per_pixel} bits per pixel"
            end
end

#bitmap24 ⇒ Object 



87
88
89
90
91
92
93
 
# File 'lib/chico/bitmapper.rb', line 87

def bitmap24
  (0...@height-1).to_a.reverse.map { |y|
    (0...@width).map { |x|
      @data[@offset + 3 * (y * @width + x), 3].unpack('CCC').values_at(2, 1, 0) + [255]
    }
  }.flatten
end

#bitmap32 ⇒ Object 



77
78
79
80
81
82
83
84
85
 
# File 'lib/chico/bitmapper.rb', line 77

def bitmap32
  (0...@height).to_a.reverse.map { |y|
    (0...@width).map { |x|
      pos = @offset + 4 * (y * @width + x)
      #puts "data[#{pos}] = #{@data[pos]}"
      @data[@offset + 4 * (y * @width + x), 4].unpack('CCCC').values_at(2, 1, 0, 3)
    }
  }.flatten
end

#bitmap8 ⇒ Object 



45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
 
# File 'lib/chico/bitmapper.rb', line 45

def bitmap8
  # assemble the color palette
  color_count = 2 ** @bits_per_pixel
  raw_colors = (0...color_count).map {|i| @data[@offset + 4 * i, 4].unpack('CCCC') }
  #puts "raw colors: " + raw_colors.inspect
  # the RGBQUAD for each palette color is (blue, green, red, reserved)
  palette = raw_colors.map {|raw| raw.values_at(2, 1, 0) }
  # get the XorMap bits
  xor_data_bits = (0...@image_size).map {|i|
    @data[@offset + 4 * color_count + i].unpack('B8').first.split('').map(&:to_i)
  }.flatten
  # get the AndMap bits
  and_row_size = ((@width + 31) >> 5) << 2
  and_data_bits = (0...(and_row_size * @height)).map {|i|
    @data[@offset + 4 * color_count + @image_size].unpack('B8').first.split('').map(&:to_i)
  }.flatten
  get_pixel = ->(x, y) {
    if and_data_bits[(@height - y - 1) * and_row_size * 8 + x] == '1'
      [0, 0, 0, 0] # transparent
    else
      # use the xor value, made solid
      bits = xor_data_bits[@bits_per_pixel * ((@height - y - 1) * @width + x), @bits_per_pixel]
      palette[bits.reduce(0) {|acc, bit| 2 * acc + bit }] + [255]
    end
  }
  (0...@height).map { |y|
    (0...@width).map { |x|
      get_pixel.call(x, y)
    }
  }.flatten
end

#parse_dib ⇒ Object 



30
31
32
33
34
35
36
37
38
39
40
41
42
43
 
# File 'lib/chico/bitmapper.rb', line 30

def parse_dib
  @offset = @data[0, 4].unpack('V').first
  unless @offset == 40
    raise "Unknown BMP format" # can't handle an ICO where the dib isn't 40 bytes
  end

  @width = @ico_direntry[:width] || @data[4, 4].unpack('V').first
  @height = @ico_direntry[:height] || @data[8, 4].unpack('V').first
  @bits_per_pixel = @data[14, 2].unpack('v').first
  @image_size = @data[24, 4].unpack('V').first
  if @image_size == 0
    @image_size = @width * @height * @bits_per_pixel / 8
  end
end

#to_stream ⇒ Object

Returns a String with the pixels, rgba, one byte per channel



23
24
25
26
27
28
 
# File 'lib/chico/bitmapper.rb', line 23

def to_stream
  sio = StringIO.new
  @pixels.each {|p| sio.putc(p) }
  sio.pos = 0
  sio
end