canvas-qr
Version:
qrcode creator based on node-canvas and qr.js
892 lines (716 loc) • 23 kB
JavaScript
/**
* qr frame data generator
* from https://github.com/neocotic/qr.js
*/
// Private constants
// -----------------
// Alignment pattern.
var ALIGNMENT_DELTA = [
0, 11, 15, 19, 23, 27, 31,
16, 18, 20, 22, 24, 26, 28, 20, 22, 24, 24, 26, 28, 28, 22, 24, 24,
26, 26, 28, 28, 24, 24, 26, 26, 26, 28, 28, 24, 26, 26, 26, 28, 28
]
// There are four elements per version. The first two indicate the number of blocks, then the
// data width, and finally the ECC width.
var ECC_BLOCKS = [
1, 0, 19, 7, 1, 0, 16, 10, 1, 0, 13, 13, 1, 0, 9, 17,
1, 0, 34, 10, 1, 0, 28, 16, 1, 0, 22, 22, 1, 0, 16, 28,
1, 0, 55, 15, 1, 0, 44, 26, 2, 0, 17, 18, 2, 0, 13, 22,
1, 0, 80, 20, 2, 0, 32, 18, 2, 0, 24, 26, 4, 0, 9, 16,
1, 0, 108, 26, 2, 0, 43, 24, 2, 2, 15, 18, 2, 2, 11, 22,
2, 0, 68, 18, 4, 0, 27, 16, 4, 0, 19, 24, 4, 0, 15, 28,
2, 0, 78, 20, 4, 0, 31, 18, 2, 4, 14, 18, 4, 1, 13, 26,
2, 0, 97, 24, 2, 2, 38, 22, 4, 2, 18, 22, 4, 2, 14, 26,
2, 0, 116, 30, 3, 2, 36, 22, 4, 4, 16, 20, 4, 4, 12, 24,
2, 2, 68, 18, 4, 1, 43, 26, 6, 2, 19, 24, 6, 2, 15, 28,
4, 0, 81, 20, 1, 4, 50, 30, 4, 4, 22, 28, 3, 8, 12, 24,
2, 2, 92, 24, 6, 2, 36, 22, 4, 6, 20, 26, 7, 4, 14, 28,
4, 0, 107, 26, 8, 1, 37, 22, 8, 4, 20, 24, 12, 4, 11, 22,
3, 1, 115, 30, 4, 5, 40, 24, 11, 5, 16, 20, 11, 5, 12, 24,
5, 1, 87, 22, 5, 5, 41, 24, 5, 7, 24, 30, 11, 7, 12, 24,
5, 1, 98, 24, 7, 3, 45, 28, 15, 2, 19, 24, 3, 13, 15, 30,
1, 5, 107, 28, 10, 1, 46, 28, 1, 15, 22, 28, 2, 17, 14, 28,
5, 1, 120, 30, 9, 4, 43, 26, 17, 1, 22, 28, 2, 19, 14, 28,
3, 4, 113, 28, 3, 11, 44, 26, 17, 4, 21, 26, 9, 16, 13, 26,
3, 5, 107, 28, 3, 13, 41, 26, 15, 5, 24, 30, 15, 10, 15, 28,
4, 4, 116, 28, 17, 0, 42, 26, 17, 6, 22, 28, 19, 6, 16, 30,
2, 7, 111, 28, 17, 0, 46, 28, 7, 16, 24, 30, 34, 0, 13, 24,
4, 5, 121, 30, 4, 14, 47, 28, 11, 14, 24, 30, 16, 14, 15, 30,
6, 4, 117, 30, 6, 14, 45, 28, 11, 16, 24, 30, 30, 2, 16, 30,
8, 4, 106, 26, 8, 13, 47, 28, 7, 22, 24, 30, 22, 13, 15, 30,
10, 2, 114, 28, 19, 4, 46, 28, 28, 6, 22, 28, 33, 4, 16, 30,
8, 4, 122, 30, 22, 3, 45, 28, 8, 26, 23, 30, 12, 28, 15, 30,
3, 10, 117, 30, 3, 23, 45, 28, 4, 31, 24, 30, 11, 31, 15, 30,
7, 7, 116, 30, 21, 7, 45, 28, 1, 37, 23, 30, 19, 26, 15, 30,
5, 10, 115, 30, 19, 10, 47, 28, 15, 25, 24, 30, 23, 25, 15, 30,
13, 3, 115, 30, 2, 29, 46, 28, 42, 1, 24, 30, 23, 28, 15, 30,
17, 0, 115, 30, 10, 23, 46, 28, 10, 35, 24, 30, 19, 35, 15, 30,
17, 1, 115, 30, 14, 21, 46, 28, 29, 19, 24, 30, 11, 46, 15, 30,
13, 6, 115, 30, 14, 23, 46, 28, 44, 7, 24, 30, 59, 1, 16, 30,
12, 7, 121, 30, 12, 26, 47, 28, 39, 14, 24, 30, 22, 41, 15, 30,
6, 14, 121, 30, 6, 34, 47, 28, 46, 10, 24, 30, 2, 64, 15, 30,
17, 4, 122, 30, 29, 14, 46, 28, 49, 10, 24, 30, 24, 46, 15, 30,
4, 18, 122, 30, 13, 32, 46, 28, 48, 14, 24, 30, 42, 32, 15, 30,
20, 4, 117, 30, 40, 7, 47, 28, 43, 22, 24, 30, 10, 67, 15, 30,
19, 6, 118, 30, 18, 31, 47, 28, 34, 34, 24, 30, 20, 61, 15, 30
]
// Map of human-readable ECC levels.
var ECC_LEVELS = {
L: 1
,M: 2
,Q: 3
,H: 4
}
// Final format bits with mask (level << 3 | mask).
var FINAL_FORMAT = [
0x77c4, 0x72f3, 0x7daa, 0x789d, 0x662f, 0x6318, 0x6c41, 0x6976, /* L */
0x5412, 0x5125, 0x5e7c, 0x5b4b, 0x45f9, 0x40ce, 0x4f97, 0x4aa0, /* M */
0x355f, 0x3068, 0x3f31, 0x3a06, 0x24b4, 0x2183, 0x2eda, 0x2bed, /* Q */
0x1689, 0x13be, 0x1ce7, 0x19d0, 0x0762, 0x0255, 0x0d0c, 0x083b /* H */
]
// Galois field exponent table.
var GALOIS_EXPONENT = [
0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26,
0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0,
0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23,
0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1,
0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0,
0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2,
0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce,
0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc,
0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54,
0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73,
0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff,
0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41,
0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6,
0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09,
0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16,
0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x00
]
// Galois field log table.
var GALOIS_LOG = [
0xff, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6, 0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b,
0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81, 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71,
0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21, 0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45,
0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9, 0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6,
0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd, 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88,
0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd, 0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40,
0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e, 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d,
0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b, 0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57,
0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d, 0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18,
0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c, 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e,
0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd, 0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61,
0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e, 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2,
0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76, 0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6,
0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa, 0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a,
0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51, 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7,
0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8, 0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf
]
// *Badness* coefficients.
var N1 = 3
var N2 = 3
var N3 = 40
var N4 = 10
// Version pattern.
var VERSION_BLOCK = [
0xc94, 0x5bc, 0xa99, 0x4d3, 0xbf6, 0x762, 0x847, 0x60d, 0x928, 0xb78, 0x45d, 0xa17, 0x532,
0x9a6, 0x683, 0x8c9, 0x7ec, 0xec4, 0x1e1, 0xfab, 0x08e, 0xc1a, 0x33f, 0xd75, 0x250, 0x9d5,
0x6f0, 0x8ba, 0x79f, 0xb0b, 0x42e, 0xa64, 0x541, 0xc69
]
// Generate the encoded QR image for the string provided.
function generateFrame(_str, ecc) {
var i, j, k, m, t, v, x, y, version
,eccLevel = ECC_LEVELS[ecc || 'L'] || 1
,str = _str || ''
,width
// Run lengths for badness.
var badBuffer = []
// Data block.
var dataBlock
// ECC data blocks and tables.
var eccBlock, neccBlock1, neccBlock2
// ECC buffer.
var eccBuffer = []
// Image buffer.
var frameBuffer = []
// Fixed part of the image.
var frameMask = []
// Generator polynomial.
var polynomial = []
// Data input buffer.
var stringBuffer = []
// functions
// Set bit to indicate cell in frame is immutable (symmetric around diagonal).
function setMask(_x, _y) {
var bit
,x = _x
,y = _y
if (x > y) {
bit = x
x = y
y = bit
}
bit = y
bit *= y
bit += y
bit >>= 1
bit += x
frameMask[bit] = 1
}
// Enter alignment pattern. Foreground colour to frame, background to mask. Frame will be merged
// with mask later.
function addAlignment(_x, _y) {
var i
,x = _x
,y = _y
frameBuffer[x + width * y] = 1
for (i = -2; i < 2; i++) {
frameBuffer[(x + i) + width * (y - 2)] = 1
frameBuffer[(x - 2) + width * (y + i + 1)] = 1
frameBuffer[(x + 2) + width * (y + i)] = 1
frameBuffer[(x + i + 1) + width * (y + 2)] = 1
}
for (i = 0; i < 2; i++) {
setMask(x - 1, y + i)
setMask(x + 1, y - i)
setMask(x - i, y - 1)
setMask(x + i, y + 1)
}
}
// Exponentiation mod N.
function modN(_x) {
var x = _x
while (x >= 255) {
x -= 255
x = (x >> 8) + (x & 255)
}
return x
}
// Calculate and append `ecc` data to the `data` block. If block is in the string buffer the
// indices to buffers are used.
function appendData(_data, _dataLength, _ecc, _eccLength) {
var bit, i, j
,data = _data
,dataLength = _dataLength
,ecc = _ecc
,eccLength = _eccLength
for (i = 0; i < eccLength; i++) {
stringBuffer[ecc + i] = 0
}
for (i = 0; i < dataLength; i++) {
bit = GALOIS_LOG[stringBuffer[data + i] ^ stringBuffer[ecc]]
if (bit !== 255) {
for (j = 1; j < eccLength; j++) {
stringBuffer[ecc + j - 1] = stringBuffer[ecc + j] ^
GALOIS_EXPONENT[modN(bit + polynomial[eccLength - j])]
}
} else {
for (j = ecc; j < ecc + eccLength; j++) {
stringBuffer[j] = stringBuffer[j + 1]
}
}
stringBuffer[ecc + eccLength - 1] = bit === 255 ? 0 :
GALOIS_EXPONENT[modN(bit + polynomial[0])]
}
}
// Check mask since symmetricals use half.
function isMasked(_x, _y) {
var bit
,x = _x
,y = _y
if (x > y) {
bit = x
x = y
y = bit
}
bit = y
bit += y * y
bit >>= 1
bit += x
return frameMask[bit] === 1
}
// Apply the selected mask out of the 8 options.
function applyMask(_mask) {
var x, y, r3x, r3y
,mask = _mask
if(mask === 0)
for (y = 0; y < width; y++) {
for (x = 0; x < width; x++) {
if (!((x + y) & 1) && !isMasked(x, y)) {
frameBuffer[x + y * width] ^= 1
}
}
}
if(mask === 1)
for (y = 0; y < width; y++) {
for (x = 0; x < width; x++) {
if (!(y & 1) && !isMasked(x, y)) {
frameBuffer[x + y * width] ^= 1
}
}
}
if(mask === 2)
for (y = 0; y < width; y++) {
for (r3x = 0, x = 0; x < width; x++, r3x++) {
if (r3x === 3) r3x = 0
if (!r3x && !isMasked(x, y)) {
frameBuffer[x + y * width] ^= 1
}
}
}
if(mask === 3)
for (r3y = 0, y = 0; y < width; y++, r3y++) {
if (r3y === 3) r3y = 0
for (r3x = r3y, x = 0; x < width; x++, r3x++) {
if (r3x === 3) r3x = 0
if (!r3x && !isMasked(x, y)) {
frameBuffer[x + y * width] ^= 1
}
}
}
if(mask === 4)
for (y = 0; y < width; y++) {
for (r3x = 0, r3y = ((y >> 1) & 1), x = 0; x < width; x++, r3x++) {
if (r3x === 3) {
r3x = 0
r3y = !r3y
}
if (!r3y && !isMasked(x, y)) {
frameBuffer[x + y * width] ^= 1
}
}
}
if(mask === 5)
for (r3y = 0, y = 0; y < width; y++, r3y++) {
if (r3y === 3) r3y = 0
for (r3x = 0, x = 0; x < width; x++, r3x++) {
if (r3x === 3) r3x = 0
if (!((x & y & 1) + !(!r3x | !r3y)) && !isMasked(x, y)) {
frameBuffer[x + y * width] ^= 1
}
}
}
if(mask === 6)
for (r3y = 0, y = 0; y < width; y++, r3y++) {
if (r3y === 3) r3y = 0
for (r3x = 0, x = 0; x < width; x++, r3x++) {
if (r3x === 3) r3x = 0
if (!(((x & y & 1) + (r3x && (r3x === r3y))) & 1) && !isMasked(x, y)) {
frameBuffer[x + y * width] ^= 1
}
}
}
if(mask === 7)
for (r3y = 0, y = 0; y < width; y++, r3y++) {
if (r3y === 3) r3y = 0
for (r3x = 0, x = 0; x < width; x++, r3x++) {
if (r3x === 3) r3x = 0
if (!(((r3x && (r3x === r3y)) + ((x + y) & 1)) & 1) && !isMasked(x, y)) {
frameBuffer[x + y * width] ^= 1
}
}
}
}
// Using the table for the length of each run, calculate the amount of bad image. Long runs or
// those that look like finders are called twice once for X and Y.
function getBadRuns(_length) {
var badRuns = 0
var i
var length = _length
for (i = 0; i <= length; i++) {
if (badBuffer[i] >= 5) {
badRuns += N1 + badBuffer[i] - 5
}
}
// FBFFFBF as in finder.
for (i = 3; i < length - 1; i += 2) {
if (badBuffer[i - 2] === badBuffer[i + 2] &&
badBuffer[i + 2] === badBuffer[i - 1] &&
badBuffer[i - 1] === badBuffer[i + 1] &&
badBuffer[i - 1] * 3 === badBuffer[i] &&
// Background around the foreground pattern? Not part of the specs.
(badBuffer[i - 3] === 0 || i + 3 > length ||
badBuffer[i - 3] * 3 >= badBuffer[i] * 4 ||
badBuffer[i + 3] * 3 >= badBuffer[i] * 4)) {
badRuns += N3
}
}
return badRuns
}
// Calculate how bad the masked image is (e.g. blocks, imbalance, runs, or finders).
function checkBadness() {
var b, b1, bad, big, bw, count, h, x, y
bad = bw = count = 0
// Blocks of same colour.
for (y = 0; y < width - 1; y++) {
for (x = 0; x < width - 1; x++) {
// All foreground colour.
if ((frameBuffer[x + width * y] &&
frameBuffer[(x + 1) + width * y] &&
frameBuffer[x + width * (y + 1)] &&
frameBuffer[(x + 1) + width * (y + 1)]) ||
// All background colour.
!(frameBuffer[x + width * y] ||
frameBuffer[(x + 1) + width * y] ||
frameBuffer[x + width * (y + 1)] ||
frameBuffer[(x + 1) + width * (y + 1)])) {
bad += N2
}
}
}
// X runs.
for (y = 0; y < width; y++) {
badBuffer[0] = 0
for (h = b = x = 0; x < width; x++) {
if ((b1 = frameBuffer[x + width * y]) === b) {
badBuffer[h]++
} else {
badBuffer[++h] = 1
}
b = b1
bw += b ? 1 : -1
}
bad += getBadRuns(h)
}
if (bw < 0) bw = -bw
big = bw
big += big << 2
big <<= 1
while (big > width * width) {
big -= width * width
count++
}
bad += count * N4
// Y runs.
for (x = 0; x < width; x++) {
badBuffer[0] = 0
for (h = b = y = 0; y < width; y++) {
if ((b1 = frameBuffer[x + width * y]) === b) {
badBuffer[h]++
} else {
badBuffer[++h] = 1
}
b = b1
}
bad += getBadRuns(h)
}
return bad
}
//end functions
// Find the smallest version that fits the string.
t = str.length
version = 0
do {
version++
k = (eccLevel - 1) * 4 + (version - 1) * 16
neccBlock1 = ECC_BLOCKS[k++]
neccBlock2 = ECC_BLOCKS[k++]
dataBlock = ECC_BLOCKS[k++]
eccBlock = ECC_BLOCKS[k]
k = dataBlock * (neccBlock1 + neccBlock2) + neccBlock2 - 3 + (version <= 9)
if (t <= k) break
} while (version < 40)
// FIXME: Ensure that it fits insted of being truncated.
width = 17 + 4 * version
// Allocate, clear and setup data structures.
v = dataBlock + (dataBlock + eccBlock) * (neccBlock1 + neccBlock2) + neccBlock2
for (t = 0; t < v; t++) {
eccBuffer[t] = 0
}
stringBuffer = str.slice(0)
for (t = 0; t < width * width; t++) {
frameBuffer[t] = 0
}
for (t = 0; t < (width * (width + 1) + 1) / 2; t++) {
frameMask[t] = 0
}
// Insert finders: Foreground colour to frame and background to mask.
for (t = 0; t < 3; t++) {
k = y = 0
if (t === 1) k = (width - 7)
if (t === 2) y = (width - 7)
frameBuffer[(y + 3) + width * (k + 3)] = 1
for (x = 0; x < 6; x++) {
frameBuffer[(y + x) + width * k] = 1
frameBuffer[y + width * (k + x + 1)] = 1
frameBuffer[(y + 6) + width * (k + x)] = 1
frameBuffer[(y + x + 1) + width * (k + 6)] = 1
}
for (x = 1; x < 5; x++) {
setMask(y + x, k + 1)
setMask(y + 1, k + x + 1)
setMask(y + 5, k + x)
setMask(y + x + 1, k + 5)
}
for (x = 2; x < 4; x++) {
frameBuffer[(y + x) + width * (k + 2)] = 1
frameBuffer[(y + 2) + width * (k + x + 1)] = 1
frameBuffer[(y + 4) + width * (k + x)] = 1
frameBuffer[(y + x + 1) + width * (k + 4)] = 1
}
}
// Alignment blocks.
if (version > 1) {
t = ALIGNMENT_DELTA[version]
y = width - 7
for (;;) {
x = width - 7
while (x > t - 3) {
addAlignment(x, y)
if (x < t) break
x -= t
}
if (y <= t + 9) break
y -= t
addAlignment(6, y)
addAlignment(y, 6)
}
}
// Single foreground cell.
frameBuffer[8 + width * (width - 8)] = 1
// Timing gap (mask only).
for (y = 0; y < 7; y++) {
setMask(7, y, width)
setMask(width - 8, y)
setMask(7, y + width - 7)
}
for (x = 0; x < 8; x++) {
setMask(x, 7)
setMask(x + width - 8, 7)
setMask(x, width - 8)
}
// Reserve mask, format area.
for (x = 0; x < 9; x++) {
setMask(x, 8)
}
for (x = 0; x < 8; x++) {
setMask(x + width - 8, 8)
setMask(8, x)
}
for (y = 0; y < 7; y++) {
setMask(8, y + width - 7)
}
// Timing row/column.
for (x = 0; x < width - 14; x++) {
if (x & 1) {
setMask(8 + x, 6)
setMask(6, 8 + x)
} else {
frameBuffer[(8 + x) + width * 6] = 1
frameBuffer[6 + width * (8 + x)] = 1
}
}
// Version block.
if (version > 6) {
t = VERSION_BLOCK[version - 7]
k = 17
for (x = 0; x < 6; x++) {
for (y = 0; y < 3; y++, k--) {
if (1 & (k > 11 ? version >> (k - 12) : t >> k)) {
frameBuffer[(5 - x) + width * (2 - y + width - 11)] = 1
frameBuffer[(2 - y + width - 11) + width * (5 - x)] = 1
} else {
setMask(5 - x, 2 - y + width - 11)
setMask(2 - y + width - 11, 5 - x)
}
}
}
}
// Sync mask bits. Only set above for background cells, so now add the foreground.
for (y = 0; y < width; y++) {
for (x = 0; x <= y; x++) {
if (frameBuffer[x + width * y]) {
setMask(x, y)
}
}
}
// Convert string to bit stream. 8-bit data to QR-coded 8-bit data (numeric, alphanum, or kanji
// not supported).
v = stringBuffer.length
// String to array.
for (i = 0; i < v; i++) {
eccBuffer[i] = stringBuffer.charCodeAt(i)
}
stringBuffer = eccBuffer.slice(0)
// Calculate max string length.
x = dataBlock * (neccBlock1 + neccBlock2) + neccBlock2
if (v >= x - 2) {
v = x - 2
if (version > 9) v--
}
// Shift and re-pack to insert length prefix.
i = v
if (version > 9) {
stringBuffer[i + 2] = 0
stringBuffer[i + 3] = 0
while (i--) {
t = stringBuffer[i]
stringBuffer[i + 3] |= 255 & (t << 4)
stringBuffer[i + 2] = t >> 4
}
stringBuffer[2] |= 255 & (v << 4)
stringBuffer[1] = v >> 4
stringBuffer[0] = 0x40 | (v >> 12)
} else {
stringBuffer[i + 1] = 0
stringBuffer[i + 2] = 0
while (i--) {
t = stringBuffer[i]
stringBuffer[i + 2] |= 255 & (t << 4)
stringBuffer[i + 1] = t >> 4
}
stringBuffer[1] |= 255 & (v << 4)
stringBuffer[0] = 0x40 | (v >> 4)
}
// Fill to end with pad pattern.
i = v + 3 - (version < 10)
while (i < x) {
stringBuffer[i++] = 0xec
stringBuffer[i++] = 0x11
}
// Calculate generator polynomial.
polynomial[0] = 1
for (i = 0; i < eccBlock; i++) {
polynomial[i + 1] = 1
for (j = i; j > 0; j--) {
polynomial[j] = polynomial[j] ? polynomial[j - 1] ^
GALOIS_EXPONENT[modN(GALOIS_LOG[polynomial[j]] + i)] : polynomial[j - 1]
}
polynomial[0] = GALOIS_EXPONENT[modN(GALOIS_LOG[polynomial[0]] + i)]
}
// Use logs for generator polynomial to save calculation step.
for (i = 0; i <= eccBlock; i++) {
polynomial[i] = GALOIS_LOG[polynomial[i]]
}
// Append ECC to data buffer.
k = x
y = 0
for (i = 0; i < neccBlock1; i++) {
appendData(y, dataBlock, k, eccBlock)
y += dataBlock
k += eccBlock
}
for (i = 0; i < neccBlock2; i++) {
appendData(y, dataBlock + 1, k, eccBlock)
y += dataBlock + 1
k += eccBlock
}
// Interleave blocks.
y = 0
for (i = 0; i < dataBlock; i++) {
for (j = 0; j < neccBlock1; j++) {
eccBuffer[y++] = stringBuffer[i + j * dataBlock]
}
for (j = 0; j < neccBlock2; j++) {
eccBuffer[y++] = stringBuffer[(neccBlock1 * dataBlock) + i + (j * (dataBlock + 1))]
}
}
for (j = 0; j < neccBlock2; j++) {
eccBuffer[y++] = stringBuffer[(neccBlock1 * dataBlock) + i + (j * (dataBlock + 1))]
}
for (i = 0; i < eccBlock; i++) {
for (j = 0; j < neccBlock1 + neccBlock2; j++) {
eccBuffer[y++] = stringBuffer[x + i + j * eccBlock]
}
}
stringBuffer = eccBuffer
// Pack bits into frame avoiding masked area.
x = y = width - 1
k = v = 1
// inteleaved data and ECC codes.
m = (dataBlock + eccBlock) * (neccBlock1 + neccBlock2) + neccBlock2
for (i = 0; i < m; i++) {
t = stringBuffer[i]
for (j = 0; j < 8; j++, t <<= 1) {
if (0x80 & t) {
frameBuffer[x + width * y] = 1
}
// Find next fill position.
do {
if (v) {
x--
} else {
x++
if (k) {
if (y !== 0) {
y--
} else {
x -= 2
k = !k
if (x === 6) {
x--
y = 9
}
}
} else {
if (y !== width - 1) {
y++
} else {
x -= 2
k = !k
if (x === 6) {
x--
y -= 8
}
}
}
}
v = !v
} while (isMasked(x, y))
}
}
// Save pre-mask copy of frame.
stringBuffer = frameBuffer.slice(0)
t = 0
y = 30000
// Using `for` instead of `while` since in original Arduino code if an early mask was *good
// enough* it wouldn't try for a better one since they get more complex and take longer.
for (k = 0; k < 8; k++) {
// Returns foreground-background imbalance.
applyMask(k)
x = checkBadness()
// Is current mask better than previous best?
if (x < y) {
y = x
t = k
}
// Don't increment `i` to a void redoing mask.
if (t === 7) break
// Reset for next pass.
frameBuffer = stringBuffer.slice(0)
}
// Redo best mask as none were *good enough* (i.e. last wasn't `t`).
if (t !== k) {
applyMask(t)
}
// Add in final mask/ECC level bytes.
y = FINAL_FORMAT[t + ((eccLevel - 1) << 3)]
// Low byte.
for (k = 0; k < 8; k++, y >>= 1) {
if (y & 1) {
frameBuffer[(width - 1 - k) + width * 8] = 1
if (k < 6) {
frameBuffer[8 + width * k] = 1
} else {
frameBuffer[8 + width * (k + 1)] = 1
}
}
}
// High byte.
for (k = 0; k < 7; k++, y >>= 1) {
if (y & 1) {
frameBuffer[8 + width * (width - 7 + k)] = 1
if (k) {
frameBuffer[(6 - k) + width * 8] = 1
} else {
frameBuffer[7 + width * 8] = 1
}
}
}
// Finally, return the image data.
return {
frameBuffer: frameBuffer
,width: width
}
}
module.exports = generateFrame