Class: QRCode::Encoder::Util

Inherits:
Object
  • Object
show all
Defined in:
lib/qrcode/encoder/util.rb

Constant Summary collapse

PATTERN_POSITION_TABLE = 
[
	[],
	[6, 18],
	[6, 22],
	[6, 26],
	[6, 30],
	[6, 34],
	[6, 22, 38],
	[6, 24, 42],
	[6, 26, 46],
	[6, 28, 50],
	[6, 30, 54],
	[6, 32, 58],
	[6, 34, 62],
	[6, 26, 46, 66],
	[6, 26, 48, 70],
	[6, 26, 50, 74],
	[6, 30, 54, 78],
	[6, 30, 56, 82],
	[6, 30, 58, 86],
	[6, 34, 62, 90],
	[6, 28, 50, 72, 94],
	[6, 26, 50, 74, 98],
	[6, 30, 54, 78, 102],
	[6, 28, 54, 80, 106],
	[6, 32, 58, 84, 110],
	[6, 30, 58, 86, 114],
	[6, 34, 62, 90, 118],
	[6, 26, 50, 74, 98, 122],
	[6, 30, 54, 78, 102, 126],
	[6, 26, 52, 78, 104, 130],
	[6, 30, 56, 82, 108, 134],
	[6, 34, 60, 86, 112, 138],
	[6, 30, 58, 86, 114, 142],
	[6, 34, 62, 90, 118, 146],
	[6, 30, 54, 78, 102, 126, 150],
	[6, 24, 50, 76, 102, 128, 154],
	[6, 28, 54, 80, 106, 132, 158],
	[6, 32, 58, 84, 110, 136, 162],
	[6, 26, 54, 82, 110, 138, 166],
	[6, 30, 58, 86, 114, 142, 170]
].freeze
G15 = 
1 << 10 | 1 << 8 | 1 << 5 | 1 << 4 | 1 << 2 | 1 << 1 | 1 << 0
G18 = 
1 << 12 | 1 << 11 | 1 << 10 | 1 << 9 | 1 << 8 | 1 << 5 | 1 << 2 | 1 << 0
G15_MASK = 
1 << 14 | 1 << 12 | 1 << 10 | 1 << 4 | 1 << 1
DEMERIT_POINTS_1 = 
3
DEMERIT_POINTS_2 = 
3
DEMERIT_POINTS_3 = 
40
DEMERIT_POINTS_4 = 
10
BITS_FOR_MODE = 
{
	MODE[:mode_number] => [10, 12, 14],
	MODE[:mode_alpha_numk] => [9, 11, 13],
	MODE[:mode_8bit_byte] => [8, 16, 16]
}.freeze
ARCH_BITS =

This value is used during the right shift zero fill step. It is auto set to 32 or 64 depending on the arch of your system running. 64 consumes a LOT more memory. In tests it’s shown changing it to 32 on 64 bit systems greatly reduces the memory footprint. You can use RQRCODE_CORE_ARCH_BITS to make this change but beware it may also have unintended consequences so use at your own risk.

ENV.fetch("RQRCODE_CORE_ARCH_BITS", nil)&.to_i || 1.size * 8

Class Method Summary collapse

Class Method Details

.demerit_points_1_same_color(modules) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 179

def self.demerit_points_1_same_color(modules)
	demerit_points = 0
	module_count = modules.size
	
	# level1
	(0...module_count).each do |row|
		(0...module_count).each do |col|
			same_count = 0
			dark = modules[row][col]
			
			(-1..1).each do |r|
				next if row + r < 0 || module_count <= row + r
				
				(-1..1).each do |c|
					next if col + c < 0 || module_count <= col + c
					next if r == 0 && c == 0
					if dark == modules[row + r][col + c]
						same_count += 1
					end
				end
			end
			
			if same_count > 5
				demerit_points += (DEMERIT_POINTS_1 + same_count - 5)
			end
		end
	end
	
	demerit_points
end

.demerit_points_2_full_blocks(modules) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 210

def self.demerit_points_2_full_blocks(modules)
	demerit_points = 0
	module_count = modules.size
	
	# level 2
	(0...(module_count - 1)).each do |row|
		(0...(module_count - 1)).each do |col|
			count = 0
			count += 1 if modules[row][col]
			count += 1 if modules[row + 1][col]
			count += 1 if modules[row][col + 1]
			count += 1 if modules[row + 1][col + 1]
			if count == 0 || count == 4
				demerit_points += DEMERIT_POINTS_2
			end
		end
	end
	
	demerit_points
end

.demerit_points_3_dangerous_patterns(modules) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 231

def self.demerit_points_3_dangerous_patterns(modules)
	demerit_points = 0
	module_count = modules.size
	
	# level 3
	modules.each do |row|
		(module_count - 6).times do |col_idx|
			if row[col_idx] && !row[col_idx + 1] && row[col_idx + 2] && row[col_idx + 3] && row[col_idx + 4] && !row[col_idx + 5] && row[col_idx + 6]
				demerit_points += DEMERIT_POINTS_3
			end
		end
	end
	
	(0...module_count).each do |col|
		(0...(module_count - 6)).each do |row|
			if modules[row][col] && !modules[row + 1][col] && modules[row + 2][col] && modules[row + 3][col] && modules[row + 4][col] && !modules[row + 5][col] && modules[row + 6][col]
				demerit_points += DEMERIT_POINTS_3
			end
		end
	end
	
	demerit_points
end

.demerit_points_4_dark_ratio(modules) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 255

def self.demerit_points_4_dark_ratio(modules)
	# level 4
	dark_count = modules.reduce(0) do |sum, col|
		sum + col.count(true)
	end
	
	# Convert to float to prevent integer division
	ratio = dark_count.to_f / (modules.size * modules.size)
	ratio_delta = (100 * ratio - 50).abs / 5
	
	ratio_delta * DEMERIT_POINTS_4
end

.get_bch_digit(data) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 112

def self.get_bch_digit(data)
	digit = 0
	
	while data != 0
		digit += 1
		data = Encoder::Util.rszf(data, 1)
	end
	
	digit
end

.get_bch_format_info(data) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 91

def self.get_bch_format_info(data)
	d = data << 10
	while Encoder::Util.get_bch_digit(d) - Encoder::Util.get_bch_digit(G15) >= 0
		d ^= (G15 << (Encoder::Util.get_bch_digit(d) - Encoder::Util.get_bch_digit(G15)))
	end
	((data << 10) | d) ^ G15_MASK
end

.get_bch_version(data) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 104

def self.get_bch_version(data)
	d = data << 12
	while Encoder::Util.get_bch_digit(d) - Encoder::Util.get_bch_digit(G18) >= 0
		d ^= (G18 << (Encoder::Util.get_bch_digit(d) - Encoder::Util.get_bch_digit(G18)))
	end
	(data << 12) | d
end

.get_error_correct_polynomial(error_correct_length) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 135

def self.get_error_correct_polynomial(error_correct_length)
	a = Encoder::Polynomial.new([1], 0)
	
	(0...error_correct_length).each do |i|
		a = a.multiply(Encoder::Polynomial.new([1, Encoder::Math.gexp(i)], 0))
	end
	
	a
end

.get_length_in_bits(mode, version) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 145

def self.get_length_in_bits(mode, version)
	if !MODE.value?(mode)
		raise RuntimeError, "Unknown mode: #{mode}"
	end
	
	if version > 40
		raise RuntimeError, "Unknown version: #{version}"
	end
	
	if version.between?(1, 9)
		# 1 - 9
		macro_version = 0
	elsif version <= 26
		# 10 - 26
		macro_version = 1
	elsif version <= 40
		# 27 - 40
		macro_version = 2
	end
	
	BITS_FOR_MODE[mode][macro_version]
end

.get_lost_points(modules) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 168

def self.get_lost_points(modules)
	demerit_points = 0
	
	demerit_points += Encoder::Util.demerit_points_1_same_color(modules)
	demerit_points += Encoder::Util.demerit_points_2_full_blocks(modules)
	demerit_points += Encoder::Util.demerit_points_3_dangerous_patterns(modules)
	demerit_points += Encoder::Util.demerit_points_4_dark_ratio(modules)
	
	demerit_points
end

.get_mask(mask_pattern, i, j) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 127

def self.get_mask(mask_pattern, i, j)
	if mask_pattern > MASK_COMPUTATIONS.size
		raise RuntimeError, "bad mask_pattern: #{mask_pattern}"
	end
	
	MASK_COMPUTATIONS[mask_pattern].call(i, j)
end

.get_pattern_positions(version) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 123

def self.get_pattern_positions(version)
	PATTERN_POSITION_TABLE[version - 1]
end

.max_size ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 87

def self.max_size
	PATTERN_POSITION_TABLE.count
end

.rszf(num, count) ⇒ Object 



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# File 'lib/qrcode/encoder/util.rb', line 99

def self.rszf(num, count)
	# right shift zero fill
	(num >> count) & ((1 << (ARCH_BITS - count)) - 1)
end