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QR-Code-generator/typescript/qrcodegen.ts

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/*
* QR Code generator library (TypeScript)
*
* Copyright (c) Project Nayuki. (MIT License)
* https://www.nayuki.io/page/qr-code-generator-library
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
* - The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* - The Software is provided "as is", without warranty of any kind, express or
* implied, including but not limited to the warranties of merchantability,
* fitness for a particular purpose and noninfringement. In no event shall the
* authors or copyright holders be liable for any claim, damages or other
* liability, whether in an action of contract, tort or otherwise, arising from,
* out of or in connection with the Software or the use or other dealings in the
* Software.
*/
"use strict";
namespace qrcodegen {
type bit = number;
type byte = number;
type int = number;
/*---- QR Code symbol class ----*/
/*
* A QR Code symbol, which is a type of two-dimension barcode.
* Invented by Denso Wave and described in the ISO/IEC 18004 standard.
* Instances of this class represent an immutable square grid of black and white cells.
* The class provides static factory functions to create a QR Code from text or binary data.
* The class covers the QR Code Model 2 specification, supporting all versions (sizes)
* from 1 to 40, all 4 error correction levels, and 4 character encoding modes.
*
* Ways to create a QR Code object:
* - High level: Take the payload data and call QrCode.encodeText() or QrCode.encodeBinary().
* - Mid level: Custom-make the list of segments and call QrCode.encodeSegments().
* - Low level: Custom-make the array of data codeword bytes (including
* segment headers and final padding, excluding error correction codewords),
* supply the appropriate version number, and call the QrCode() constructor.
* (Note that all ways require supplying the desired error correction level.)
*/
export class QrCode {
/*-- Static factory functions (high level) --*/
// Returns a QR Code representing the given Unicode text string at the given error correction level.
// As a conservative upper bound, this function is guaranteed to succeed for strings that have 738 or fewer
// Unicode code points (not UTF-16 code units) if the low error correction level is used. The smallest possible
// QR Code version is automatically chosen for the output. The ECC level of the result may be higher than the
// ecl argument if it can be done without increasing the version.
public static encodeText(text: string, ecl: QrCode.Ecc): QrCode {
const segs: Array<QrSegment> = qrcodegen.QrSegment.makeSegments(text);
return QrCode.encodeSegments(segs, ecl);
}
// Returns a QR Code representing the given binary data at the given error correction level.
// This function always encodes using the binary segment mode, not any text mode. The maximum number of
// bytes allowed is 2953. The smallest possible QR Code version is automatically chosen for the output.
// The ECC level of the result may be higher than the ecl argument if it can be done without increasing the version.
public static encodeBinary(data: Array<byte>, ecl: QrCode.Ecc): QrCode {
const seg: QrSegment = qrcodegen.QrSegment.makeBytes(data);
return QrCode.encodeSegments([seg], ecl);
}
/*-- Static factory functions (mid level) --*/
// Returns a QR Code representing the given segments with the given encoding parameters.
// The smallest possible QR Code version within the given range is automatically
// chosen for the output. Iff boostEcl is true, then the ECC level of the result
// may be higher than the ecl argument if it can be done without increasing the
// version. The mask number is either between 0 to 7 (inclusive) to force that
// mask, or -1 to automatically choose an appropriate mask (which may be slow).
// This function allows the user to create a custom sequence of segments that switches
// between modes (such as alphanumeric and byte) to encode text in less space.
// This is a mid-level API; the high-level API is encodeText() and encodeBinary().
public static encodeSegments(segs: Array<QrSegment>, ecl: QrCode.Ecc,
minVersion: int = 1, maxVersion: int = 40,
mask: int = -1, boostEcl: boolean = true): QrCode {
if (!(QrCode.MIN_VERSION <= minVersion && minVersion <= maxVersion && maxVersion <= QrCode.MAX_VERSION)
|| mask < -1 || mask > 7)
throw "Invalid value";
// Find the minimal version number to use
let version: int;
let dataUsedBits: int;
for (version = minVersion; ; version++) {
const dataCapacityBits: int = QrCode.getNumDataCodewords(version, ecl) * 8; // Number of data bits available
const usedBits: number = QrSegment.getTotalBits(segs, version);
if (usedBits <= dataCapacityBits) {
dataUsedBits = usedBits;
break; // This version number is found to be suitable
}
if (version >= maxVersion) // All versions in the range could not fit the given data
throw "Data too long";
}
// Increase the error correction level while the data still fits in the current version number
for (const newEcl of [QrCode.Ecc.MEDIUM, QrCode.Ecc.QUARTILE, QrCode.Ecc.HIGH]) { // From low to high
if (boostEcl && dataUsedBits <= QrCode.getNumDataCodewords(version, newEcl) * 8)
ecl = newEcl;
}
// Concatenate all segments to create the data bit string
let bb = new BitBuffer();
for (const seg of segs) {
bb.appendBits(seg.mode.modeBits, 4);
bb.appendBits(seg.numChars, seg.mode.numCharCountBits(version));
for (const b of seg.getData())
bb.push(b);
}
if (bb.length != dataUsedBits)
throw "Assertion error";
// Add terminator and pad up to a byte if applicable
const dataCapacityBits: int = QrCode.getNumDataCodewords(version, ecl) * 8;
if (bb.length > dataCapacityBits)
throw "Assertion error";
bb.appendBits(0, Math.min(4, dataCapacityBits - bb.length));
bb.appendBits(0, (8 - bb.length % 8) % 8);
if (bb.length % 8 != 0)
throw "Assertion error";
// Pad with alternating bytes until data capacity is reached
for (let padByte = 0xEC; bb.length < dataCapacityBits; padByte ^= 0xEC ^ 0x11)
bb.appendBits(padByte, 8);
// Pack bits into bytes in big endian
let dataCodewords: Array<byte> = [];
while (dataCodewords.length * 8 < bb.length)
dataCodewords.push(0);
bb.forEach((b: bit, i: int) =>
dataCodewords[i >>> 3] |= b << (7 - (i & 7)));
// Create the QR Code object
return new QrCode(version, ecl, dataCodewords, mask);
}
/*-- Fields --*/
// The width and height of this QR Code, measured in modules, between
// 21 and 177 (inclusive). This is equal to version * 4 + 17.
public readonly size: int;
// The modules of this QR Code (false = white, true = black).
// Immutable after constructor finishes. Accessed through getModule().
private readonly modules : Array<Array<boolean>> = [];
// Indicates function modules that are not subjected to masking. Discarded when constructor finishes.
private readonly isFunction: Array<Array<boolean>> = [];
/*-- Constructor (low level) and fields --*/
// Creates a new QR Code with the given version number,
// error correction level, data codeword bytes, and mask number.
// This is a low-level API that most users should not use directly.
// A mid-level API is the encodeSegments() function.
public constructor(
// The version number of this QR Code, which is between 1 and 40 (inclusive).
// This determines the size of this barcode.
public readonly version: int,
// The error correction level used in this QR Code.
public readonly errorCorrectionLevel: QrCode.Ecc,
dataCodewords: Array<byte>,
// The index of the mask pattern used in this QR Code, which is between 0 and 7 (inclusive).
// Even if a QR Code is created with automatic masking requested (mask = -1),
// the resulting object still has a mask value between 0 and 7.
public readonly mask: int) {
// Check scalar arguments
if (version < QrCode.MIN_VERSION || version > QrCode.MAX_VERSION)
throw "Version value out of range";
if (mask < -1 || mask > 7)
throw "Mask value out of range";
this.size = version * 4 + 17;
// Initialize both grids to be size*size arrays of Boolean false
let row: Array<boolean> = [];
for (let i = 0; i < this.size; i++)
row.push(false);
for (let i = 0; i < this.size; i++) {
this.modules .push(row.slice()); // Initially all white
this.isFunction.push(row.slice());
}
// Compute ECC, draw modules
this.drawFunctionPatterns();
const allCodewords: Array<byte> = this.addEccAndInterleave(dataCodewords);
this.drawCodewords(allCodewords);
// Do masking
if (mask == -1) { // Automatically choose best mask
let minPenalty: int = 1000000000;
for (let i = 0; i < 8; i++) {
this.applyMask(i);
this.drawFormatBits(i);
const penalty: int = this.getPenaltyScore();
if (penalty < minPenalty) {
mask = i;
minPenalty = penalty;
}
this.applyMask(i); // Undoes the mask due to XOR
}
}
if (mask < 0 || mask > 7)
throw "Assertion error";
this.mask = mask;
this.applyMask(mask); // Apply the final choice of mask
this.drawFormatBits(mask); // Overwrite old format bits
this.isFunction = [];
}
/*-- Accessor methods --*/
// Returns the color of the module (pixel) at the given coordinates, which is false
// for white or true for black. The top left corner has the coordinates (x=0, y=0).
// If the given coordinates are out of bounds, then false (white) is returned.
public getModule(x: int, y: int): boolean {
return 0 <= x && x < this.size && 0 <= y && y < this.size && this.modules[y][x];
}
/*-- Public instance methods --*/
// Draws this QR Code, with the given module scale and border modules, onto the given HTML
// canvas element. The canvas's width and height is resized to (this.size + border * 2) * scale.
// The drawn image is be purely black and white, and fully opaque.
// The scale must be a positive integer and the border must be a non-negative integer.
public drawCanvas(scale: int, border: int, canvas: HTMLCanvasElement): void {
if (scale <= 0 || border < 0)
throw "Value out of range";
const width: int = (this.size + border * 2) * scale;
canvas.width = width;
canvas.height = width;
let ctx = canvas.getContext("2d") as CanvasRenderingContext2D;
for (let y = -border; y < this.size + border; y++) {
for (let x = -border; x < this.size + border; x++) {
ctx.fillStyle = this.getModule(x, y) ? "#000000" : "#FFFFFF";
ctx.fillRect((x + border) * scale, (y + border) * scale, scale, scale);
}
}
}
// Returns a string of SVG code for an image depicting this QR Code, with the given number
// of border modules. The string always uses Unix newlines (\n), regardless of the platform.
public toSvgString(border: int): string {
if (border < 0)
throw "Border must be non-negative";
let parts: Array<string> = [];
for (let y = 0; y < this.size; y++) {
for (let x = 0; x < this.size; x++) {
if (this.getModule(x, y))
parts.push(`M${x + border},${y + border}h1v1h-1z`);
}
}
return `<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg xmlns="http://www.w3.org/2000/svg" version="1.1" viewBox="0 0 ${this.size + border * 2} ${this.size + border * 2}" stroke="none">
<rect width="100%" height="100%" fill="#FFFFFF"/>
<path d="${parts.join(" ")}" fill="#000000"/>
</svg>
`
}
/*-- Private helper methods for constructor: Drawing function modules --*/
// Reads this object's version field, and draws and marks all function modules.
private drawFunctionPatterns(): void {
// Draw horizontal and vertical timing patterns
for (let i = 0; i < this.size; i++) {
this.setFunctionModule(6, i, i % 2 == 0);
this.setFunctionModule(i, 6, i % 2 == 0);
}
// Draw 3 finder patterns (all corners except bottom right; overwrites some timing modules)
this.drawFinderPattern(3, 3);
this.drawFinderPattern(this.size - 4, 3);
this.drawFinderPattern(3, this.size - 4);
// Draw numerous alignment patterns
const alignPatPos: Array<int> = this.getAlignmentPatternPositions();
const numAlign: int = alignPatPos.length;
for (let i = 0; i < numAlign; i++) {
for (let j = 0; j < numAlign; j++) {
// Don't draw on the three finder corners
if (!(i == 0 && j == 0 || i == 0 && j == numAlign - 1 || i == numAlign - 1 && j == 0))
this.drawAlignmentPattern(alignPatPos[i], alignPatPos[j]);
}
}
// Draw configuration data
this.drawFormatBits(0); // Dummy mask value; overwritten later in the constructor
this.drawVersion();
}
// Draws two copies of the format bits (with its own error correction code)
// based on the given mask and this object's error correction level field.
private drawFormatBits(mask: int): void {
// Calculate error correction code and pack bits
const data: int = this.errorCorrectionLevel.formatBits << 3 | mask; // errCorrLvl is uint2, mask is uint3
let rem: int = data;
for (let i = 0; i < 10; i++)
rem = (rem << 1) ^ ((rem >>> 9) * 0x537);
const bits = (data << 10 | rem) ^ 0x5412; // uint15
if (bits >>> 15 != 0)
throw "Assertion error";
// Draw first copy
for (let i = 0; i <= 5; i++)
this.setFunctionModule(8, i, getBit(bits, i));
this.setFunctionModule(8, 7, getBit(bits, 6));
this.setFunctionModule(8, 8, getBit(bits, 7));
this.setFunctionModule(7, 8, getBit(bits, 8));
for (let i = 9; i < 15; i++)
this.setFunctionModule(14 - i, 8, getBit(bits, i));
// Draw second copy
for (let i = 0; i < 8; i++)
this.setFunctionModule(this.size - 1 - i, 8, getBit(bits, i));
for (let i = 8; i < 15; i++)
this.setFunctionModule(8, this.size - 15 + i, getBit(bits, i));
this.setFunctionModule(8, this.size - 8, true); // Always black
}
// Draws two copies of the version bits (with its own error correction code),
// based on this object's version field, iff 7 <= version <= 40.
private drawVersion(): void {
if (this.version < 7)
return;
// Calculate error correction code and pack bits
let rem: int = this.version; // version is uint6, in the range [7, 40]
for (let i = 0; i < 12; i++)
rem = (rem << 1) ^ ((rem >>> 11) * 0x1F25);
const bits: int = this.version << 12 | rem; // uint18
if (bits >>> 18 != 0)
throw "Assertion error";
// Draw two copies
for (let i = 0; i < 18; i++) {
const color: boolean = getBit(bits, i);
const a: int = this.size - 11 + i % 3;
const b: int = Math.floor(i / 3);
this.setFunctionModule(a, b, color);
this.setFunctionModule(b, a, color);
}
}
// Draws a 9*9 finder pattern including the border separator,
// with the center module at (x, y). Modules can be out of bounds.
private drawFinderPattern(x: int, y: int): void {
for (let dy = -4; dy <= 4; dy++) {
for (let dx = -4; dx <= 4; dx++) {
const dist: int = Math.max(Math.abs(dx), Math.abs(dy)); // Chebyshev/infinity norm
const xx: int = x + dx;
const yy: int = y + dy;
if (0 <= xx && xx < this.size && 0 <= yy && yy < this.size)
this.setFunctionModule(xx, yy, dist != 2 && dist != 4);
}
}
}
// Draws a 5*5 alignment pattern, with the center module
// at (x, y). All modules must be in bounds.
private drawAlignmentPattern(x: int, y: int): void {
for (let dy = -2; dy <= 2; dy++) {
for (let dx = -2; dx <= 2; dx++)
this.setFunctionModule(x + dx, y + dy, Math.max(Math.abs(dx), Math.abs(dy)) != 1);
}
}
// Sets the color of a module and marks it as a function module.
// Only used by the constructor. Coordinates must be in bounds.
private setFunctionModule(x: int, y: int, isBlack: boolean): void {
this.modules[y][x] = isBlack;
this.isFunction[y][x] = true;
}
/*-- Private helper methods for constructor: Codewords and masking --*/
// Returns a new byte string representing the given data with the appropriate error correction
// codewords appended to it, based on this object's version and error correction level.
private addEccAndInterleave(data: Array<byte>): Array<byte> {
const ver: int = this.version;
const ecl: QrCode.Ecc = this.errorCorrectionLevel;
if (data.length != QrCode.getNumDataCodewords(ver, ecl))
throw "Invalid argument";
// Calculate parameter numbers
const numBlocks: int = QrCode.NUM_ERROR_CORRECTION_BLOCKS[ecl.ordinal][ver];
const blockEccLen: int = QrCode.ECC_CODEWORDS_PER_BLOCK [ecl.ordinal][ver];
const rawCodewords: int = Math.floor(QrCode.getNumRawDataModules(ver) / 8);
const numShortBlocks: int = numBlocks - rawCodewords % numBlocks;
const shortBlockLen: int = Math.floor(rawCodewords / numBlocks);
// Split data into blocks and append ECC to each block
let blocks: Array<Array<byte>> = [];
const rs = new ReedSolomonGenerator(blockEccLen);
for (let i = 0, k = 0; i < numBlocks; i++) {
let dat: Array<byte> = data.slice(k, k + shortBlockLen - blockEccLen + (i < numShortBlocks ? 0 : 1));
k += dat.length;
const ecc: Array<byte> = rs.getRemainder(dat);
if (i < numShortBlocks)
dat.push(0);
blocks.push(dat.concat(ecc));
}
// Interleave (not concatenate) the bytes from every block into a single sequence
let result: Array<byte> = [];
for (let i = 0; i < blocks[0].length; i++) {
for (let j = 0; j < blocks.length; j++) {
// Skip the padding byte in short blocks
if (i != shortBlockLen - blockEccLen || j >= numShortBlocks)
result.push(blocks[j][i]);
}
}
if (result.length != rawCodewords)
throw "Assertion error";
return result;
}
// Draws the given sequence of 8-bit codewords (data and error correction) onto the entire
// data area of this QR Code. Function modules need to be marked off before this is called.
private drawCodewords(data: Array<byte>): void {
if (data.length != Math.floor(QrCode.getNumRawDataModules(this.version) / 8))
throw "Invalid argument";
let i: int = 0; // Bit index into the data
// Do the funny zigzag scan
for (let right = this.size - 1; right >= 1; right -= 2) { // Index of right column in each column pair
if (right == 6)
right = 5;
for (let vert = 0; vert < this.size; vert++) { // Vertical counter
for (let j = 0; j < 2; j++) {
const x: int = right - j; // Actual x coordinate
const upward: boolean = ((right + 1) & 2) == 0;
const y: int = upward ? this.size - 1 - vert : vert; // Actual y coordinate
if (!this.isFunction[y][x] && i < data.length * 8) {
this.modules[y][x] = getBit(data[i >>> 3], 7 - (i & 7));
i++;
}
// If this QR Code has any remainder bits (0 to 7), they were assigned as
// 0/false/white by the constructor and are left unchanged by this method
}
}
}
if (i != data.length * 8)
throw "Assertion error";
}
// XORs the codeword modules in this QR Code with the given mask pattern.
// The function modules must be marked and the codeword bits must be drawn
// before masking. Due to the arithmetic of XOR, calling applyMask() with
// the same mask value a second time will undo the mask. A final well-formed
// QR Code needs exactly one (not zero, two, etc.) mask applied.
private applyMask(mask: int): void {
if (mask < 0 || mask > 7)
throw "Mask value out of range";
for (let y = 0; y < this.size; y++) {
for (let x = 0; x < this.size; x++) {
let invert: boolean;
switch (mask) {
case 0: invert = (x + y) % 2 == 0; break;
case 1: invert = y % 2 == 0; break;
case 2: invert = x % 3 == 0; break;
case 3: invert = (x + y) % 3 == 0; break;
case 4: invert = (Math.floor(x / 3) + Math.floor(y / 2)) % 2 == 0; break;
case 5: invert = x * y % 2 + x * y % 3 == 0; break;
case 6: invert = (x * y % 2 + x * y % 3) % 2 == 0; break;
case 7: invert = ((x + y) % 2 + x * y % 3) % 2 == 0; break;
default: throw "Assertion error";
}
if (!this.isFunction[y][x] && invert)
this.modules[y][x] = !this.modules[y][x];
}
}
}
// Calculates and returns the penalty score based on state of this QR Code's current modules.
// This is used by the automatic mask choice algorithm to find the mask pattern that yields the lowest score.
private getPenaltyScore(): int {
let result: int = 0;
// Adjacent modules in row having same color, and finder-like patterns
for (let y = 0; y < this.size; y++) {
let runHistory = [0,0,0,0,0,0,0];
let color = false;
let runX = 0;
for (let x = 0; x < this.size; x++) {
if (this.modules[y][x] == color) {
runX++;
if (runX == 5)
result += QrCode.PENALTY_N1;
else if (runX > 5)
result++;
} else {
QrCode.addRunToHistory(runX, runHistory);
if (!color && QrCode.hasFinderLikePattern(runHistory))
result += QrCode.PENALTY_N3;
color = this.modules[y][x];
runX = 1;
}
}
QrCode.addRunToHistory(runX, runHistory);
if (color)
QrCode.addRunToHistory(0, runHistory); // Dummy run of white
if (QrCode.hasFinderLikePattern(runHistory))
result += QrCode.PENALTY_N3;
}
// Adjacent modules in column having same color, and finder-like patterns
for (let x = 0; x < this.size; x++) {
let runHistory = [0,0,0,0,0,0,0];
let color = false;
let runY = 0;
for (let y = 0; y < this.size; y++) {
if (this.modules[y][x] == color) {
runY++;
if (runY == 5)
result += QrCode.PENALTY_N1;
else if (runY > 5)
result++;
} else {
QrCode.addRunToHistory(runY, runHistory);
if (!color && QrCode.hasFinderLikePattern(runHistory))
result += QrCode.PENALTY_N3;
color = this.modules[y][x];
runY = 1;
}
}
QrCode.addRunToHistory(runY, runHistory);
if (color)
QrCode.addRunToHistory(0, runHistory); // Dummy run of white
if (QrCode.hasFinderLikePattern(runHistory))
result += QrCode.PENALTY_N3;
}
// 2*2 blocks of modules having same color
for (let y = 0; y < this.size - 1; y++) {
for (let x = 0; x < this.size - 1; x++) {
const color: boolean = this.modules[y][x];
if ( color == this.modules[y][x + 1] &&
color == this.modules[y + 1][x] &&
color == this.modules[y + 1][x + 1])
result += QrCode.PENALTY_N2;
}
}
// Balance of black and white modules
let black: int = 0;
for (const row of this.modules) {
for (const color of row) {
if (color)
black++;
}
}
const total: int = this.size * this.size; // Note that size is odd, so black/total != 1/2
// Compute the smallest integer k >= 0 such that (45-5k)% <= black/total <= (55+5k)%
const k: int = Math.ceil(Math.abs(black * 20 - total * 10) / total) - 1;
result += k * QrCode.PENALTY_N4;
return result;
}
/*-- Private helper functions --*/
// Returns an ascending list of positions of alignment patterns for this version number.
// Each position is in the range [0,177), and are used on both the x and y axes.
// This could be implemented as lookup table of 40 variable-length lists of integers.
private getAlignmentPatternPositions(): Array<int> {
if (this.version == 1)
return [];
else {
const numAlign: int = Math.floor(this.version / 7) + 2;
const step: int = (this.version == 32) ? 26 :
Math.ceil((this.size - 13) / (numAlign*2 - 2)) * 2;
let result: Array<int> = [6];
for (let pos = this.size - 7; result.length < numAlign; pos -= step)
result.splice(1, 0, pos);
return result;
}
}
// Returns the number of data bits that can be stored in a QR Code of the given version number, after
// all function modules are excluded. This includes remainder bits, so it might not be a multiple of 8.
// The result is in the range [208, 29648]. This could be implemented as a 40-entry lookup table.
private static getNumRawDataModules(ver: int): int {
if (ver < QrCode.MIN_VERSION || ver > QrCode.MAX_VERSION)
throw "Version number out of range";
let result: int = (16 * ver + 128) * ver + 64;
if (ver >= 2) {
const numAlign: int = Math.floor(ver / 7) + 2;
result -= (25 * numAlign - 10) * numAlign - 55;
if (ver >= 7)
result -= 36;
}
return result;
}
// Returns the number of 8-bit data (i.e. not error correction) codewords contained in any
// QR Code of the given version number and error correction level, with remainder bits discarded.
// This stateless pure function could be implemented as a (40*4)-cell lookup table.
private static getNumDataCodewords(ver: int, ecl: QrCode.Ecc): int {
return Math.floor(QrCode.getNumRawDataModules(ver) / 8) -
QrCode.ECC_CODEWORDS_PER_BLOCK [ecl.ordinal][ver] *
QrCode.NUM_ERROR_CORRECTION_BLOCKS[ecl.ordinal][ver];
}
// Inserts the given value to the front of the given array, which shifts over the
// existing values and deletes the last value. A helper function for getPenaltyScore().
private static addRunToHistory(run: int, history: Array<int>): void {
history.pop();
history.unshift(run);
}
// Tests whether the given run history has the pattern of ratio 1:1:3:1:1 in the middle, and
// surrounded by at least 4 on either or both ends. A helper function for getPenaltyScore().
// Must only be called immediately after a run of white modules has ended.
private static hasFinderLikePattern(runHistory: Array<int>): boolean {
const n: int = runHistory[1];
return n > 0 && runHistory[2] == n && runHistory[4] == n && runHistory[5] == n
&& runHistory[3] == n * 3 && Math.max(runHistory[0], runHistory[6]) >= n * 4;
}
/*-- Constants and tables --*/
// The minimum version number supported in the QR Code Model 2 standard.
public static readonly MIN_VERSION: int = 1;
// The maximum version number supported in the QR Code Model 2 standard.
public static readonly MAX_VERSION: int = 40;
// For use in getPenaltyScore(), when evaluating which mask is best.
private static readonly PENALTY_N1: int = 3;
private static readonly PENALTY_N2: int = 3;
private static readonly PENALTY_N3: int = 40;
private static readonly PENALTY_N4: int = 10;
private static readonly ECC_CODEWORDS_PER_BLOCK: Array<Array<int>> = [
// Version: (note that index 0 is for padding, and is set to an illegal value)
//0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 Error correction level
[-1, 7, 10, 15, 20, 26, 18, 20, 24, 30, 18, 20, 24, 26, 30, 22, 24, 28, 30, 28, 28, 28, 28, 30, 30, 26, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30], // Low
[-1, 10, 16, 26, 18, 24, 16, 18, 22, 22, 26, 30, 22, 22, 24, 24, 28, 28, 26, 26, 26, 26, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28], // Medium
[-1, 13, 22, 18, 26, 18, 24, 18, 22, 20, 24, 28, 26, 24, 20, 30, 24, 28, 28, 26, 30, 28, 30, 30, 30, 30, 28, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30], // Quartile
[-1, 17, 28, 22, 16, 22, 28, 26, 26, 24, 28, 24, 28, 22, 24, 24, 30, 28, 28, 26, 28, 30, 24, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30, 30], // High
];
private static readonly NUM_ERROR_CORRECTION_BLOCKS: Array<Array<int>> = [
// Version: (note that index 0 is for padding, and is set to an illegal value)
//0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 Error correction level
[-1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 4, 4, 4, 4, 4, 6, 6, 6, 6, 7, 8, 8, 9, 9, 10, 12, 12, 12, 13, 14, 15, 16, 17, 18, 19, 19, 20, 21, 22, 24, 25], // Low
[-1, 1, 1, 1, 2, 2, 4, 4, 4, 5, 5, 5, 8, 9, 9, 10, 10, 11, 13, 14, 16, 17, 17, 18, 20, 21, 23, 25, 26, 28, 29, 31, 33, 35, 37, 38, 40, 43, 45, 47, 49], // Medium
[-1, 1, 1, 2, 2, 4, 4, 6, 6, 8, 8, 8, 10, 12, 16, 12, 17, 16, 18, 21, 20, 23, 23, 25, 27, 29, 34, 34, 35, 38, 40, 43, 45, 48, 51, 53, 56, 59, 62, 65, 68], // Quartile
[-1, 1, 1, 2, 4, 4, 4, 5, 6, 8, 8, 11, 11, 16, 16, 18, 16, 19, 21, 25, 25, 25, 34, 30, 32, 35, 37, 40, 42, 45, 48, 51, 54, 57, 60, 63, 66, 70, 74, 77, 81], // High
];
}
// Returns true iff the i'th bit of x is set to 1.
function getBit(x: int, i: int): boolean {
return ((x >>> i) & 1) != 0;
}
/*---- Data segment class ----*/
/*
* A segment of character/binary/control data in a QR Code symbol.
* Instances of this class are immutable.
* The mid-level way to create a segment is to take the payload data
* and call a static factory function such as QrSegment.makeNumeric().
* The low-level way to create a segment is to custom-make the bit buffer
* and call the QrSegment() constructor with appropriate values.
* This segment class imposes no length restrictions, but QR Codes have restrictions.
* Even in the most favorable conditions, a QR Code can only hold 7089 characters of data.
* Any segment longer than this is meaningless for the purpose of generating QR Codes.
*/
export class QrSegment {
/*-- Static factory functions (mid level) --*/
// Returns a segment representing the given binary data encoded in
// byte mode. All input byte arrays are acceptable. Any text string
// can be converted to UTF-8 bytes and encoded as a byte mode segment.
public static makeBytes(data: Array<byte>): QrSegment {
let bb = new BitBuffer();
for (const b of data)
bb.appendBits(b, 8);
return new QrSegment(QrSegment.Mode.BYTE, data.length, bb);
}
// Returns a segment representing the given string of decimal digits encoded in numeric mode.
public static makeNumeric(digits: string): QrSegment {
if (!this.NUMERIC_REGEX.test(digits))
throw "String contains non-numeric characters";
let bb = new BitBuffer();
for (let i = 0; i < digits.length; ) { // Consume up to 3 digits per iteration
const n: int = Math.min(digits.length - i, 3);
bb.appendBits(parseInt(digits.substr(i, n), 10), n * 3 + 1);
i += n;
}
return new QrSegment(QrSegment.Mode.NUMERIC, digits.length, bb);
}
// Returns a segment representing the given text string encoded in alphanumeric mode.
// The characters allowed are: 0 to 9, A to Z (uppercase only), space,
// dollar, percent, asterisk, plus, hyphen, period, slash, colon.
public static makeAlphanumeric(text: string): QrSegment {
if (!this.ALPHANUMERIC_REGEX.test(text))
throw "String contains unencodable characters in alphanumeric mode";
let bb = new BitBuffer();
let i: int;
for (i = 0; i + 2 <= text.length; i += 2) { // Process groups of 2
let temp: int = QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i)) * 45;
temp += QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i + 1));
bb.appendBits(temp, 11);
}
if (i < text.length) // 1 character remaining
bb.appendBits(QrSegment.ALPHANUMERIC_CHARSET.indexOf(text.charAt(i)), 6);
return new QrSegment(QrSegment.Mode.ALPHANUMERIC, text.length, bb);
}
// Returns a new mutable list of zero or more segments to represent the given Unicode text string.
// The result may use various segment modes and switch modes to optimize the length of the bit stream.
public static makeSegments(text: string): Array<QrSegment> {
// Select the most efficient segment encoding automatically
if (text == "")
return [];
else if (this.NUMERIC_REGEX.test(text))
return [QrSegment.makeNumeric(text)];
else if (this.ALPHANUMERIC_REGEX.test(text))
return [QrSegment.makeAlphanumeric(text)];
else
return [QrSegment.makeBytes(QrSegment.toUtf8ByteArray(text))];
}
// Returns a segment representing an Extended Channel Interpretation
// (ECI) designator with the given assignment value.
public static makeEci(assignVal: int): QrSegment {
let bb = new BitBuffer();
if (assignVal < 0)
throw "ECI assignment value out of range";
else if (assignVal < (1 << 7))
bb.appendBits(assignVal, 8);
else if (assignVal < (1 << 14)) {
bb.appendBits(2, 2);
bb.appendBits(assignVal, 14);
} else if (assignVal < 1000000) {
bb.appendBits(6, 3);
bb.appendBits(assignVal, 21);
} else
throw "ECI assignment value out of range";
return new QrSegment(QrSegment.Mode.ECI, 0, bb);
}
/*-- Constructor (low level) and fields --*/
// Creates a new QR Code segment with the given attributes and data.
// The character count (numChars) must agree with the mode and the bit buffer length,
// but the constraint isn't checked. The given bit buffer is cloned and stored.
public constructor(
// The mode indicator of this segment.
public readonly mode: QrSegment.Mode,
// The length of this segment's unencoded data. Measured in characters for
// numeric/alphanumeric/kanji mode, bytes for byte mode, and 0 for ECI mode.
// Always zero or positive. Not the same as the data's bit length.
public readonly numChars: int,
// The data bits of this segment. Accessed through getData().
private readonly bitData: Array<bit>) {
if (numChars < 0)
throw "Invalid argument";
this.bitData = bitData.slice(); // Make defensive copy
}
/*-- Methods --*/
// Returns a new copy of the data bits of this segment.
public getData(): Array<bit> {
return this.bitData.slice(); // Make defensive copy
}
// (Package-private) Calculates and returns the number of bits needed to encode the given segments at
// the given version. The result is infinity if a segment has too many characters to fit its length field.
public static getTotalBits(segs: Array<QrSegment>, version: int): number {
let result: number = 0;
for (const seg of segs) {
const ccbits: int = seg.mode.numCharCountBits(version);
if (seg.numChars >= (1 << ccbits))
return Infinity; // The segment's length doesn't fit the field's bit width
result += 4 + ccbits + seg.bitData.length;
}
return result;
}
// Returns a new array of bytes representing the given string encoded in UTF-8.
private static toUtf8ByteArray(str: string): Array<byte> {
str = encodeURI(str);
let result: Array<byte> = [];
for (let i = 0; i < str.length; i++) {
if (str.charAt(i) != "%")
result.push(str.charCodeAt(i));
else {
result.push(parseInt(str.substr(i + 1, 2), 16));
i += 2;
}
}
return result;
}
/*-- Constants --*/
// Describes precisely all strings that are encodable in numeric mode. To test
// whether a string s is encodable: let ok: boolean = NUMERIC_REGEX.test(s);
// A string is encodable iff each character is in the range 0 to 9.
public static readonly NUMERIC_REGEX: RegExp = /^[0-9]*$/;
// Describes precisely all strings that are encodable in alphanumeric mode. To test
// whether a string s is encodable: let ok: boolean = ALPHANUMERIC_REGEX.test(s);
// A string is encodable iff each character is in the following set: 0 to 9, A to Z
// (uppercase only), space, dollar, percent, asterisk, plus, hyphen, period, slash, colon.
public static readonly ALPHANUMERIC_REGEX: RegExp = /^[A-Z0-9 $%*+.\/:-]*$/;
// The set of all legal characters in alphanumeric mode,
// where each character value maps to the index in the string.
private static readonly ALPHANUMERIC_CHARSET: string = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";
}
/*---- Private helper classes ----*/
/*
* Computes the Reed-Solomon error correction codewords for a sequence of data codewords
* at a given degree. Objects are immutable, and the state only depends on the degree.
* This class exists because each data block in a QR Code shares the same the divisor polynomial.
*/
class ReedSolomonGenerator {
// Coefficients of the divisor polynomial, stored from highest to lowest power, excluding the leading term which
// is always 1. For example the polynomial x^3 + 255x^2 + 8x + 93 is stored as the uint8 array {255, 8, 93}.
private readonly coefficients: Array<byte> = [];
// Creates a Reed-Solomon ECC generator for the given degree. This could be implemented
// as a lookup table over all possible parameter values, instead of as an algorithm.
public constructor(degree: int) {
if (degree < 1 || degree > 255)
throw "Degree out of range";
let coefs = this.coefficients;
// Start with the monomial x^0
for (let i = 0; i < degree - 1; i++)
coefs.push(0);
coefs.push(1);
// Compute the product polynomial (x - r^0) * (x - r^1) * (x - r^2) * ... * (x - r^{degree-1}),
// drop the highest term, and store the rest of the coefficients in order of descending powers.
// Note that r = 0x02, which is a generator element of this field GF(2^8/0x11D).
let root = 1;
for (let i = 0; i < degree; i++) {
// Multiply the current product by (x - r^i)
for (let j = 0; j < coefs.length; j++) {
coefs[j] = ReedSolomonGenerator.multiply(coefs[j], root);
if (j + 1 < coefs.length)
coefs[j] ^= coefs[j + 1];
}
root = ReedSolomonGenerator.multiply(root, 0x02);
}
}
// Computes and returns the Reed-Solomon error correction codewords for the given
// sequence of data codewords. The returned object is always a new byte array.
// This method does not alter this object's state (because it is immutable).
public getRemainder(data: Array<byte>): Array<byte> {
// Compute the remainder by performing polynomial division
let result: Array<byte> = this.coefficients.map(_ => 0);
for (const b of data) {
const factor: byte = b ^ (result.shift() as byte);
result.push(0);
this.coefficients.forEach((coef, i) =>
result[i] ^= ReedSolomonGenerator.multiply(coef, factor));
}
return result;
}
// Returns the product of the two given field elements modulo GF(2^8/0x11D). The arguments and result
// are unsigned 8-bit integers. This could be implemented as a lookup table of 256*256 entries of uint8.
private static multiply(x: byte, y: byte): byte {
if (x >>> 8 != 0 || y >>> 8 != 0)
throw "Byte out of range";
// Russian peasant multiplication
let z: int = 0;
for (let i = 7; i >= 0; i--) {
z = (z << 1) ^ ((z >>> 7) * 0x11D);
z ^= ((y >>> i) & 1) * x;
}
if (z >>> 8 != 0)
throw "Assertion error";
return z as byte;
}
}
/*
* An appendable sequence of bits (0s and 1s). Mainly used by QrSegment.
* The implicit constructor creates an empty bit buffer (length 0).
*/
class BitBuffer extends Array<bit> {
// Appends the given number of low-order bits of the given value
// to this buffer. Requires 0 <= len <= 31 and 0 <= val < 2^len.
public appendBits(val: int, len: int): void {
if (len < 0 || len > 31 || val >>> len != 0)
throw "Value out of range";
for (let i = len - 1; i >= 0; i--) // Append bit by bit
this.push((val >>> i) & 1);
}
}
}
/*---- Public helper enumeration ----*/
namespace qrcodegen.QrCode {
type int = number;
/*
* The error correction level in a QR Code symbol. Immutable.
*/
export class Ecc {
/*-- Constants --*/
public static readonly LOW = new Ecc(0, 1); // The QR Code can tolerate about 7% erroneous codewords
public static readonly MEDIUM = new Ecc(1, 0); // The QR Code can tolerate about 15% erroneous codewords
public static readonly QUARTILE = new Ecc(2, 3); // The QR Code can tolerate about 25% erroneous codewords
public static readonly HIGH = new Ecc(3, 2); // The QR Code can tolerate about 30% erroneous codewords
/*-- Constructor and fields --*/
private constructor(
// In the range 0 to 3 (unsigned 2-bit integer).
public readonly ordinal: int,
// (Package-private) In the range 0 to 3 (unsigned 2-bit integer).
public readonly formatBits: int) {}
}
}
/*---- Public helper enumeration ----*/
namespace qrcodegen.QrSegment {
type int = number;
/*
* Describes how a segment's data bits are interpreted. Immutable.
*/
export class Mode {
/*-- Constants --*/
public static readonly NUMERIC = new Mode(0x1, [10, 12, 14]);
public static readonly ALPHANUMERIC = new Mode(0x2, [ 9, 11, 13]);
public static readonly BYTE = new Mode(0x4, [ 8, 16, 16]);
public static readonly KANJI = new Mode(0x8, [ 8, 10, 12]);
public static readonly ECI = new Mode(0x7, [ 0, 0, 0]);
/*-- Constructor and fields --*/
private constructor(
// The mode indicator bits, which is a uint4 value (range 0 to 15).
public readonly modeBits: int,
// Number of character count bits for three different version ranges.
private readonly numBitsCharCount: [int,int,int]) {}
/*-- Method --*/
// (Package-private) Returns the bit width of the character count field for a segment in
// this mode in a QR Code at the given version number. The result is in the range [0, 16].
public numCharCountBits(ver: int): int {
return this.numBitsCharCount[Math.floor((ver + 7) / 17)];
}
}
}
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