Add dep

vendor/github.com/skip2/go-qrcode/symbol.go

@@ -0,0 +1,309 @@
+// go-qrcode
+// Copyright 2014 Tom Harwood
+
+package qrcode
+
+// symbol is a 2D array of bits representing a QR Code symbol.
+//
+// A symbol consists of size*size modules, with each module normally drawn as a
+// black or white square. The symbol also has a border of quietZoneSize modules.
+//
+// A (fictional) size=2, quietZoneSize=1 QR Code looks like:
+//
+// +----+
+// |    |
+// | ab |
+// | cd |
+// |    |
+// +----+
+//
+// For ease of implementation, the functions to set/get bits ignore the border,
+// so (0,0)=a, (0,1)=b, (1,0)=c, and (1,1)=d. The entire symbol (including the
+// border) is returned by bitmap().
+//
+type symbol struct {
+	// Value of module at [y][x]. True is set.
+	module [][]bool
+
+	// True if the module at [y][x] is used (to either true or false).
+	// Used to identify unused modules.
+	isUsed [][]bool
+
+	// Combined width/height of the symbol and quiet zones.
+	//
+	// size = symbolSize + 2*quietZoneSize.
+	size int
+
+	// Width/height of the symbol only.
+	symbolSize int
+
+	// Width/height of a single quiet zone.
+	quietZoneSize int
+}
+
+// newSymbol constructs a symbol of size size*size, with a border of
+// quietZoneSize.
+func newSymbol(size int, quietZoneSize int) *symbol {
+	var m symbol
+
+	m.module = make([][]bool, size+2*quietZoneSize)
+	m.isUsed = make([][]bool, size+2*quietZoneSize)
+
+	for i := range m.module {
+		m.module[i] = make([]bool, size+2*quietZoneSize)
+		m.isUsed[i] = make([]bool, size+2*quietZoneSize)
+	}
+
+	m.size = size + 2*quietZoneSize
+	m.symbolSize = size
+	m.quietZoneSize = quietZoneSize
+
+	return &m
+}
+
+// get returns the module value at (x, y).
+func (m *symbol) get(x int, y int) (v bool) {
+	v = m.module[y+m.quietZoneSize][x+m.quietZoneSize]
+	return
+}
+
+// empty returns true if the module at (x, y) has not been set (to either true
+// or false).
+func (m *symbol) empty(x int, y int) bool {
+	return !m.isUsed[y+m.quietZoneSize][x+m.quietZoneSize]
+}
+
+// numEmptyModules returns the number of empty modules.
+//
+// Initially numEmptyModules is symbolSize * symbolSize. After every module has
+// been set (to either true or false), the number of empty modules is zero.
+func (m *symbol) numEmptyModules() int {
+	var count int
+	for y := 0; y < m.symbolSize; y++ {
+		for x := 0; x < m.symbolSize; x++ {
+			if !m.isUsed[y+m.quietZoneSize][x+m.quietZoneSize] {
+				count++
+			}
+		}
+	}
+
+	return count
+}
+
+// set sets the module at (x, y) to v.
+func (m *symbol) set(x int, y int, v bool) {
+	m.module[y+m.quietZoneSize][x+m.quietZoneSize] = v
+	m.isUsed[y+m.quietZoneSize][x+m.quietZoneSize] = true
+}
+
+// set2dPattern sets a 2D array of modules, starting at (x, y).
+func (m *symbol) set2dPattern(x int, y int, v [][]bool) {
+	for j, row := range v {
+		for i, value := range row {
+			m.set(x+i, y+j, value)
+		}
+	}
+}
+
+// bitmap returns the entire symbol, including the quiet zone.
+func (m *symbol) bitmap() [][]bool {
+	module := make([][]bool, len(m.module))
+
+	for i := range m.module {
+		module[i] = m.module[i][:]
+	}
+
+	return module
+}
+
+// string returns a pictorial representation of the symbol, suitable for
+// printing in a TTY.
+func (m *symbol) string() string {
+	var result string
+
+	for _, row := range m.module {
+		for _, value := range row {
+			switch value {
+			case true:
+				result += "  "
+			case false:
+				// Unicode 'FULL BLOCK' (U+2588).
+				result += "██"
+			}
+		}
+		result += "\n"
+	}
+
+	return result
+}
+
+// Constants used to weight penalty calculations. Specified by ISO/IEC
+// 18004:2006.
+const (
+	penaltyWeight1 = 3
+	penaltyWeight2 = 3
+	penaltyWeight3 = 40
+	penaltyWeight4 = 10
+)
+
+// penaltyScore returns the penalty score of the symbol. The penalty score
+// consists of the sum of the four individual penalty types.
+func (m *symbol) penaltyScore() int {
+	return m.penalty1() + m.penalty2() + m.penalty3() + m.penalty4()
+}
+
+// penalty1 returns the penalty score for "adjacent modules in row/column with
+// same colour".
+//
+// The numbers of adjacent matching modules and scores are:
+// 0-5: score = 0
+// 6+ : score = penaltyWeight1 + (numAdjacentModules - 5)
+func (m *symbol) penalty1() int {
+	penalty := 0
+
+	for x := 0; x < m.symbolSize; x++ {
+		lastValue := m.get(x, 0)
+		count := 1
+
+		for y := 1; y < m.symbolSize; y++ {
+			v := m.get(x, y)
+
+			if v != lastValue {
+				count = 1
+				lastValue = v
+			} else {
+				count++
+				if count == 6 {
+					penalty += penaltyWeight1 + 1
+				} else if count > 6 {
+					penalty++
+				}
+			}
+		}
+	}
+
+	for y := 0; y < m.symbolSize; y++ {
+		lastValue := m.get(0, y)
+		count := 1
+
+		for x := 1; x < m.symbolSize; x++ {
+			v := m.get(x, y)
+
+			if v != lastValue {
+				count = 1
+				lastValue = v
+			} else {
+				count++
+				if count == 6 {
+					penalty += penaltyWeight1 + 1
+				} else if count > 6 {
+					penalty++
+				}
+			}
+		}
+	}
+
+	return penalty
+}
+
+// penalty2 returns the penalty score for "block of modules in the same colour".
+//
+// m*n: score = penaltyWeight2 * (m-1) * (n-1).
+func (m *symbol) penalty2() int {
+	penalty := 0
+
+	for y := 1; y < m.symbolSize; y++ {
+		for x := 1; x < m.symbolSize; x++ {
+			topLeft := m.get(x-1, y-1)
+			above := m.get(x, y-1)
+			left := m.get(x-1, y)
+			current := m.get(x, y)
+
+			if current == left && current == above && current == topLeft {
+				penalty++
+			}
+		}
+	}
+
+	return penalty * penaltyWeight2
+}
+
+// penalty3 returns the penalty score for "1:1:3:1:1 ratio
+// (dark:light:dark:light:dark) pattern in row/column, preceded or followed by
+// light area 4 modules wide".
+//
+// Existence of the pattern scores penaltyWeight3.
+func (m *symbol) penalty3() int {
+	penalty := 0
+
+	for y := 0; y < m.symbolSize; y++ {
+		var bitBuffer int16 = 0x00
+
+		for x := 0; x < m.symbolSize; x++ {
+			bitBuffer <<= 1
+			if v := m.get(x, y); v {
+				bitBuffer |= 1
+			}
+
+			switch bitBuffer & 0x7ff {
+			// 0b000 0101 1101 or 0b10111010000
+			// 0x05d           or 0x5d0
+			case 0x05d, 0x5d0:
+				penalty += penaltyWeight3
+				bitBuffer = 0xFF
+			default:
+				if x == m.symbolSize-1 && (bitBuffer&0x7f) == 0x5d {
+					penalty += penaltyWeight3
+					bitBuffer = 0xFF
+				}
+			}
+		}
+	}
+
+	for x := 0; x < m.symbolSize; x++ {
+		var bitBuffer int16 = 0x00
+
+		for y := 0; y < m.symbolSize; y++ {
+			bitBuffer <<= 1
+			if v := m.get(x, y); v {
+				bitBuffer |= 1
+			}
+
+			switch bitBuffer & 0x7ff {
+			// 0b000 0101 1101 or 0b10111010000
+			// 0x05d           or 0x5d0
+			case 0x05d, 0x5d0:
+				penalty += penaltyWeight3
+				bitBuffer = 0xFF
+			default:
+				if y == m.symbolSize-1 && (bitBuffer&0x7f) == 0x5d {
+					penalty += penaltyWeight3
+					bitBuffer = 0xFF
+				}
+			}
+		}
+	}
+
+	return penalty
+}
+
+// penalty4 returns the penalty score...
+func (m *symbol) penalty4() int {
+	numModules := m.symbolSize * m.symbolSize
+	numDarkModules := 0
+
+	for x := 0; x < m.symbolSize; x++ {
+		for y := 0; y < m.symbolSize; y++ {
+			if v := m.get(x, y); v {
+				numDarkModules++
+			}
+		}
+	}
+
+	numDarkModuleDeviation := numModules/2 - numDarkModules
+	if numDarkModuleDeviation < 0 {
+		numDarkModuleDeviation *= -1
+	}
+
+	return penaltyWeight4 * (numDarkModuleDeviation / (numModules / 20))
+}