Class: Qrio::Qr

Inherits:
Object
  • Object
show all
Includes:
ImageDumper
Defined in:
lib/qrio/qr.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ImageDumper

#color, #save_image, #save_to_image

Constructor Details

#initialize ⇒ Qr

Returns a new instance of Qr.



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# File 'lib/qrio/qr.rb', line 6

def initialize
  initialize_storage
end

Instance Attribute Details

#candidates ⇒ Object (readonly)

Returns the value of attribute candidates.



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# File 'lib/qrio/qr.rb', line 3

def candidates
  @candidates
end

#finder_patterns ⇒ Object (readonly)

Returns the value of attribute finder_patterns.



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# File 'lib/qrio/qr.rb', line 3

def finder_patterns
  @finder_patterns
end

#matches ⇒ Object (readonly)

Returns the value of attribute matches.



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# File 'lib/qrio/qr.rb', line 3

def matches
  @matches
end

#qr ⇒ Object (readonly)

Returns the value of attribute qr.



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# File 'lib/qrio/qr.rb', line 3

def qr
  @qr
end

#qr_bounds ⇒ Object (readonly)

Returns the value of attribute qr_bounds.



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# File 'lib/qrio/qr.rb', line 3

def qr_bounds
  @qr_bounds
end

Class Method Details

.load(filename) ⇒ Object 



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# File 'lib/qrio/qr.rb', line 10

def self.load(filename)
  instance = new
  instance.load_image(filename)

  instance.scan(:horizontal)
  instance.scan(:vertical)

  instance.filter_candidates
  instance.find_intersections
  instance.set_qr_bounds

  instance.build_normalized_qr
  instance.find_alignment_pattern

  instance
end

Instance Method Details

#add_candidate(new_candidate, direction) ⇒ Object 



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# File 'lib/qrio/qr.rb', line 67

def add_candidate(new_candidate, direction)
  added = false

  @candidates[direction].each_with_index do |existing, index|
    if new_candidate.adjacent?(existing)
      @candidates[direction][index] = existing.union(new_candidate)
      added = true
    end
  end

  @candidates[direction] << new_candidate unless added
end

#build_normalized_qr ⇒ Object

extract the qr into a smaller matrix and rotate to standard orientation



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# File 'lib/qrio/qr.rb', line 128

def build_normalized_qr
  return false if @sampling_grid.nil?

  original_orientation = @sampling_grid.orientation

  @sampling_grid.normalize
  @extracted_matrix = @sampling_grid.matrix

  bits = []
  @sampling_grid.extracted_pixels do |x, y|
    bits << @extracted_matrix[x, y]
  end
  @qr = QrMatrix.new(bits, @sampling_grid.logical_width, @sampling_grid.logical_height)

  @translated_matches = {
    :horizontal => [],
    :vertical   => []
  }
  @translated_finder_patterns = []
  @translated_neighbors = []

  @matches[:horizontal].each do |m|
    m = m.translate(*@qr_bounds.top_left)
    if original_orientation > 0
      (4 - original_orientation).times do
        m = m.rotate(@qr_bounds.width, @qr_bounds.height)
      end
    end
    @translated_matches[:horizontal] << m
  end

  @matches[:vertical].each do |m|
    m = m.translate(*@qr_bounds.top_left)
    if original_orientation > 0
      (4 - original_orientation).times do
        m = m.rotate(@qr_bounds.width, @qr_bounds.height)
      end
    end
    @translated_matches[:vertical] << m
  end
end

#filter_candidates ⇒ Object 



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# File 'lib/qrio/qr.rb', line 80

def filter_candidates
  [:horizontal, :vertical].each do |direction|
    @candidates[direction].uniq.each do |candidate|
      @matches[direction] << candidate if candidate.matches_aspect_ratio?
    end
  end
end

#find_alignment_pattern ⇒ Object 



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# File 'lib/qrio/qr.rb', line 170

def find_alignment_pattern
  test_x = @sampling_grid.top_right.center.first - (@sampling_grid.block_width * 3)
  test_y = @sampling_grid.bottom_left.center.last - (@sampling_grid.block_height * 3)

  test_x = (test_x - @sampling_grid.block_width  / 2.0).round
  test_y = (test_y - @sampling_grid.block_height / 2.0).round

  # TODO : this is where the AP *should* be, given no image skew.
  # starting here, find center of nearest blob that "looks" like an AP.
  # offset from predicted will be used in sampling grid to account for skew
  @alignment_pattern = Qrio::Region.new(
    test_x, test_y,
    (test_x + @sampling_grid.block_width).round,
    (test_y + @sampling_grid.block_height).round
  )
end

#find_candidate(offset, origin, segment, direction) ⇒ Object 



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# File 'lib/qrio/qr.rb', line 63

def find_candidate(offset, origin, segment, direction)
  FinderPatternSlice.build_matching(offset, origin, segment, direction)
end

#find_intersections ⇒ Object

find intersections of horizontal and vertical slices, these are (likely) finder patterns



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# File 'lib/qrio/qr.rb', line 112

def find_intersections
  @matches[:horizontal].each do |h|
    @matches[:vertical].each do |v|
      @finder_patterns << h.union(v) if h.intersects?(v)
    end
  end
end

#load_image(filename) ⇒ Object 



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# File 'lib/qrio/qr.rb', line 27

def load_image(filename)
  initialize_storage

  image_type = File.extname(filename).upcase.gsub('.', '')
  image_loader_class = "#{ image_type }ImageLoader"
  image_loader_class = ImageLoader.const_get(image_loader_class) rescue nil

  if image_loader_class.nil?
    raise "Image type '#{ image_type }' not supported"
  end

  @input_matrix = image_loader_class.load(filename)
end

#rle(vector) ⇒ Object

transform a vector of bits in to a run-length encoded vector of widths example: [1, 1, 1, 1, 0, 0, 1, 1, 1] => [4, 2, 3]



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# File 'lib/qrio/qr.rb', line 90

def rle(vector)
  v = vector.dup

  pattern = []
  length = 1
  last = v.shift

  v.each do |current|
    if current === last
      length += 1
    else
      pattern << length
      length = 1
      last = current
    end
  end

  pattern << length
end

#scan(direction) ⇒ Object 



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# File 'lib/qrio/qr.rb', line 41

def scan(direction)
  vectors = direction == :horizontal ? @input_matrix.rows : @input_matrix.columns
  vectors.each_with_index do |vector, offset|
    pattern = rle(vector)

    if pattern.length >= 5
      origin = 0
      segment = pattern.slice!(0,4)

      while next_length = pattern.shift
        segment << next_length

        if candidate = find_candidate(offset, origin, segment, direction)
          add_candidate(candidate, direction)
        end

        origin += segment.shift
      end
    end
  end
end

#set_qr_bounds ⇒ Object 



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# File 'lib/qrio/qr.rb', line 120

def set_qr_bounds
  if @finder_patterns.length >= 3
    @sampling_grid = SamplingGrid.new(@input_matrix, @finder_patterns)
    @qr_bounds = @sampling_grid.bounds
  end
end