/*
* Fast QR Code generator library
*
* Copyright (c) Project Nayuki. (MIT License)
* https://www.nayuki.io/page/fast-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.
*/
package io.nayuki.fastqrcodegen;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
/**
* A QR Code symbol, which is a type of two-dimension barcode.
* Invented by Denso Wave and described in the ISO/IEC 18004 standard.
* <p>Instances of this class represent an immutable square grid of dark and light 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.</p>
* <p>Ways to create a QR Code object:</p>
* <ul>
* <li><p>High level: Take the payload data and call {@link QrCode#encodeText(String,Ecc)}
* or {@link QrCode#encodeBinary(byte[],Ecc)}.</p></li>
* <li><p>Mid level: Custom-make the list of {@link QrSegment segments}
* and call {@link QrCode#encodeSegments(List,Ecc)} or
* {@link QrCode#encodeSegments(List,Ecc,int,int,int,boolean)}</p></li>
* <li><p>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 {@link QrCode#QrCode(int,Ecc,byte[],int) constructor}.</p></li>
* </ul>
* <p>(Note that all ways require supplying the desired error correction level.)</p>
* @see QrSegment
*/
public final class QrCode {
/*---- Static factory functions (high level) ----*/
/**
* Returns a QR Code representing the specified Unicode text string at the specified 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.
* @param text the text to be encoded (not {@code null}), which can be any Unicode string
* @param ecl the error correction level to use (not {@code null}) (boostable)
* @return a QR Code (not {@code null}) representing the text
* @throws NullPointerException if the text or error correction level is {@code null}
* @throws DataTooLongException if the text fails to fit in the
* largest version QR Code at the ECL, which means it is too long
*/
public static QrCode encodeText(String text, Ecc ecl) {
Objects.requireNonNull(text);
Objects.requireNonNull(ecl);
List<QrSegment> segs = QrSegment.makeSegments(text);
return encodeSegments(segs, ecl);
}
/**
* Returns a QR Code representing the specified binary data at the specified 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.
* @param data the binary data to encode (not {@code null})
* @param ecl the error correction level to use (not {@code null}) (boostable)
* @return a QR Code (not {@code null}) representing the data
* @throws NullPointerException if the data or error correction level is {@code null}
* @throws DataTooLongException if the data fails to fit in the
* largest version QR Code at the ECL, which means it is too long
*/
public static QrCode encodeBinary(byte[] data, Ecc ecl) {
Objects.requireNonNull(data);
Objects.requireNonNull(ecl);
QrSegment seg = QrSegment.makeBytes(data);
return encodeSegments(Arrays.asList(seg), ecl);
}
/*---- Static factory functions (mid level) ----*/
/**
* Returns a QR Code representing the specified segments at the specified error correction
* level. 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.
* <p>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 {@link #encodeText(String,Ecc)}
* and {@link #encodeBinary(byte[],Ecc)}.</p>
* @param segs the segments to encode
* @param ecl the error correction level to use (not {@code null}) (boostable)
* @return a QR Code (not {@code null}) representing the segments
* @throws NullPointerException if the list of segments, any segment, or the error correction level is {@code null}
* @throws DataTooLongException if the segments fail to fit in the
* largest version QR Code at the ECL, which means they are too long
*/
public static QrCode encodeSegments(List<QrSegment> segs, Ecc ecl) {
return encodeSegments(segs, ecl, MIN_VERSION, MAX_VERSION, -1, true);
}
/**
* Returns a QR Code representing the specified segments with the specified encoding parameters.
* The smallest possible QR Code version within the specified range is automatically
* chosen for the output. Iff boostEcl is {@code 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).
* <p>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 {@link #encodeText(String,Ecc)}
* and {@link #encodeBinary(byte[],Ecc)}.</p>
* @param segs the segments to encode
* @param ecl the error correction level to use (not {@code null}) (boostable)
* @param minVersion the minimum allowed version of the QR Code (at least 1)
* @param maxVersion the maximum allowed version of the QR Code (at most 40)
* @param mask the mask number to use (between 0 and 7 (inclusive)), or −1 for automatic mask
* @param boostEcl increases the ECC level as long as it doesn't increase the version number
* @return a QR Code (not {@code null}) representing the segments
* @throws NullPointerException if the list of segments, any segment, or the error correction level is {@code null}
* @throws IllegalArgumentException if 1 ≤ minVersion ≤ maxVersion ≤ 40
* or −1 ≤ mask ≤ 7 is violated
* @throws DataTooLongException if the segments fail to fit in
* the maxVersion QR Code at the ECL, which means they are too long
*/
public static QrCode encodeSegments(List<QrSegment> segs, Ecc ecl, int minVersion, int maxVersion, int mask, boolean boostEcl) {
Objects.requireNonNull(segs);
Objects.requireNonNull(ecl);
if (!(MIN_VERSION <= minVersion && minVersion <= maxVersion && maxVersion <= MAX_VERSION) || mask < -1 || mask > 7)
throw new IllegalArgumentException("Invalid value");
// Find the minimal version number to use
int version, dataUsedBits;
for (version = minVersion; ; version++) {
int dataCapacityBits = getNumDataCodewords(version, ecl) * 8; // Number of data bits available
dataUsedBits = QrSegment.getTotalBits(segs, version);
if (dataUsedBits != -1 && dataUsedBits <= dataCapacityBits)
break; // This version number is found to be suitable
if (version >= maxVersion) { // All versions in the range could not fit the given data
String msg = "Segment too long";
if (dataUsedBits != -1)
msg = String.format("Data length = %d bits, Max capacity = %d bits", dataUsedBits, dataCapacityBits);
throw new DataTooLongException(msg);
}
}
assert dataUsedBits != -1;
// Increase the error correction level while the data still fits in the current version number
for (Ecc newEcl : Ecc.values()) { // From low to high
if (boostEcl && dataUsedBits <= getNumDataCodewords(version, newEcl) * 8)
ecl = newEcl;
}
// Concatenate all segments to create the data bit string
BitBuffer bb = new BitBuffer();
for (QrSegment seg : segs) {
bb.appendBits(seg.mode.modeBits, 4);
bb.appendBits(seg.numChars, seg.mode.numCharCountBits(version));
bb.appendBits(seg.data, seg.bitLength);
}
assert bb.bitLength == dataUsedBits;
// Add terminator and pad up to a byte if applicable
int dataCapacityBits = getNumDataCodewords(version, ecl) * 8;
assert bb.bitLength <= dataCapacityBits;
bb.appendBits(0, Math.min(4, dataCapacityBits - bb.bitLength));
bb.appendBits(0, (8 - bb.bitLength % 8) % 8);
assert bb.bitLength % 8 == 0;
// Pad with alternating bytes until data capacity is reached
for (int padByte = 0xEC; bb.bitLength < dataCapacityBits; padByte ^= 0xEC ^ 0x11)
bb.appendBits(padByte, 8);
// Create the QR Code object
return new QrCode(version, ecl, bb.getBytes(), mask);
}
/*---- Instance fields ----*/
// Public immutable scalar parameters:
/** The version number of this QR Code, which is between 1 and 40 (inclusive).
* This determines the size of this barcode. */
public final int version;
/** The width and height of this QR Code, measured in modules, between
* 21 and 177 (inclusive). This is equal to version × 4 + 17. */
public final int size;
/** The error correction level used in this QR Code, which is not {@code null}. */
public final Ecc errorCorrectionLevel;
/** The index of the mask pattern used in this QR Code, which is between 0 and 7 (inclusive).
* <p>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 final int mask;
// Private grid of modules of this QR Code, packed tightly into bits.
// Immutable after constructor finishes. Accessed through getModule().
private final int[] modules;
/*---- Constructor (low level) ----*/
/**
* Constructs a QR Code with the specified version number,
* error correction level, data codeword bytes, and mask number.
* <p>This is a low-level API that most users should not use directly. A mid-level
* API is the {@link #encodeSegments(List,Ecc,int,int,int,boolean)} function.</p>
* @param ver the version number to use, which must be in the range 1 to 40 (inclusive)
* @param ecl the error correction level to use
* @param dataCodewords the bytes representing segments to encode (without ECC)
* @param msk the mask pattern to use, which is either −1 for automatic choice or from 0 to 7 for fixed choice
* @throws NullPointerException if the byte array or error correction level is {@code null}
* @throws IllegalArgumentException if the version or mask value is out of range,
* or if the data is the wrong length for the specified version and error correction level
*/
public QrCode(int ver, Ecc ecl, byte[] dataCodewords, int msk) {
// Check arguments and initialize fields
if (ver < MIN_VERSION || ver > MAX_VERSION)
throw new IllegalArgumentException("Version value out of range");
if (msk < -1 || msk > 7)
throw new IllegalArgumentException("Mask value out of range");
version = ver;
size = ver * 4 + 17;
errorCorrectionLevel = Objects.requireNonNull(ecl);
Objects.requireNonNull(dataCodewords);
QrTemplate tpl = QrTemplate.MEMOIZER.get(ver);
modules = tpl.template.clone();
// Compute ECC, draw modules, do masking
byte[] allCodewords = addEccAndInterleave(dataCodewords);
drawCodewords(tpl.dataOutputBitIndexes, allCodewords);
mask = handleConstructorMasking(tpl.masks, msk);
}
/*---- Public instance methods ----*/
/**
* Returns the color of the module (pixel) at the specified coordinates, which is {@code false}
* for light or {@code true} for dark. The top left corner has the coordinates (x=0, y=0).
* If the specified coordinates are out of bounds, then {@code false} (light) is returned.
* @param x the x coordinate, where 0 is the left edge and size−1 is the right edge
* @param y the y coordinate, where 0 is the top edge and size−1 is the bottom edge
* @return {@code true} if the coordinates are in bounds and the module
* at that location is dark, or {@code false} (light) otherwise
*/
public boolean getModule(int x, int y) {
if (0 <= x && x < size && 0 <= y && y < size) {
int i = y * size + x;
return getBit(modules[i >>> 5], i) != 0;
} else
return false;
}
/*---- Private helper methods for constructor: Drawing function modules ----*/
// 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 void drawFormatBits(int msk) {
// Calculate error correction code and pack bits
int data = errorCorrectionLevel.formatBits << 3 | msk; // errCorrLvl is uint2, mask is uint3
int rem = data;
for (int i = 0; i < 10; i++)
rem = (rem << 1) ^ ((rem >>> 9) * 0x537);
int bits = (data << 10 | rem) ^ 0x5412; // uint15
assert bits >>> 15 == 0;
// Draw first copy
for (int i = 0; i <= 5; i++)
setModule(8, i, getBit(bits, i));
setModule(8, 7, getBit(bits, 6));
setModule(8, 8, getBit(bits, 7));
setModule(7, 8, getBit(bits, 8));
for (int i = 9; i < 15; i++)
setModule(14 - i, 8, getBit(bits, i));
// Draw second copy
for (int i = 0; i < 8; i++)
setModule(size - 1 - i, 8, getBit(bits, i));
for (int i = 8; i < 15; i++)
setModule(8, size - 15 + i, getBit(bits, i));
setModule(8, size - 8, 1); // Always dark
}
// Sets the module at the given coordinates to the given color.
// Only used by the constructor. Coordinates must be in bounds.
private void setModule(int x, int y, int dark) {
assert 0 <= x && x < size;
assert 0 <= y && y < size;
assert dark == 0 || dark == 1;
int i = y * size + x;
modules[i >>> 5] &= ~(1 << i);
modules[i >>> 5] |= dark << i;
}
/*---- 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 byte[] addEccAndInterleave(byte[] data) {
Objects.requireNonNull(data);
if (data.length != getNumDataCodewords(version, errorCorrectionLevel))
throw new IllegalArgumentException();
// Calculate parameter numbers
int numBlocks = NUM_ERROR_CORRECTION_BLOCKS[errorCorrectionLevel.ordinal()][version];
int blockEccLen = ECC_CODEWORDS_PER_BLOCK [errorCorrectionLevel.ordinal()][version];
int rawCodewords = QrTemplate.getNumRawDataModules(version) / 8;
int numShortBlocks = numBlocks - rawCodewords % numBlocks;
int shortBlockDataLen = rawCodewords / numBlocks - blockEccLen;
// Split data into blocks, calculate ECC, and interleave
// (not concatenate) the bytes into a single sequence
byte[] result = new byte[rawCodewords];
ReedSolomonGenerator rs = ReedSolomonGenerator.MEMOIZER.get(blockEccLen);
byte[] ecc = new byte[blockEccLen]; // Temporary storage per iteration
for (int i = 0, k = 0; i < numBlocks; i++) {
int datLen = shortBlockDataLen + (i < numShortBlocks ? 0 : 1);
rs.getRemainder(data, k, datLen, ecc);
for (int j = 0, l = i; j < datLen; j++, k++, l += numBlocks) { // Copy data
if (j == shortBlockDataLen)
l -= numShortBlocks;
result[l] = data[k];
}
for (int j = 0, l = data.length + i; j < blockEccLen; j++, l += numBlocks) // Copy ECC
result[l] = ecc[j];
}
return result;
}
// Draws the given sequence of 8-bit codewords (data and error correction)
// onto the entire data area of this QR Code, based on the given bit indexes.
private void drawCodewords(int[] dataOutputBitIndexes, byte[] allCodewords) {
Objects.requireNonNull(dataOutputBitIndexes);
Objects.requireNonNull(allCodewords);
if (allCodewords.length * 8 != dataOutputBitIndexes.length)
throw new IllegalArgumentException();
for (int i = 0; i < dataOutputBitIndexes.length; i++) {
int j = dataOutputBitIndexes[i];
int bit = getBit(allCodewords[i >>> 3], ~i & 7);
modules[j >>> 5] |= bit << j;
}
}
// 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 void applyMask(int[] msk) {
if (msk.length != modules.length)
throw new IllegalArgumentException();
for (int i = 0; i < msk.length; i++)
modules[i] ^= msk[i];
}
// A messy helper function for the constructor. This QR Code must be in an unmasked state when this
// method is called. The 'mask' argument is the requested mask, which is -1 for auto or 0 to 7 for fixed.
// This method applies and returns the actual mask chosen, from 0 to 7.
private int handleConstructorMasking(int[][] masks, int msk) {
if (msk == -1) { // Automatically choose best mask
int minPenalty = Integer.MAX_VALUE;
for (int i = 0; i < 8; i++) {
applyMask(masks[i]);
drawFormatBits(i);
int penalty = getPenaltyScore();
if (penalty < minPenalty) {
msk = i;
minPenalty = penalty;
}
applyMask(masks[i]); // Undoes the mask due to XOR
}
}
assert 0 <= msk && msk <= 7;
applyMask(masks[msk]); // Apply the final choice of mask
drawFormatBits(msk); // Overwrite old format bits
return msk; // The caller shall assign this value to the final-declared field
}
// 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 int getPenaltyScore() {
int result = 0;
int dark = 0;
int[] runHistory = new int[7];
// Iterate over adjacent pairs of rows
for (int index = 0, downIndex = size, end = size * size; index < end; ) {
int runColor = 0;
int runX = 0;
Arrays.fill(runHistory, 0);
int curRow = 0;
int nextRow = 0;
for (int x = 0; x < size; x++, index++, downIndex++) {
int c = getBit(modules[index >>> 5], index);
if (c == runColor) {
runX++;
if (runX == 5)
result += PENALTY_N1;
else if (runX > 5)
result++;
} else {
finderPenaltyAddHistory(runX, runHistory);
if (runColor == 0)
result += finderPenaltyCountPatterns(runHistory) * PENALTY_N3;
runColor = c;
runX = 1;
}
dark += c;
if (downIndex < end) {
curRow = ((curRow << 1) | c) & 3;
nextRow = ((nextRow << 1) | getBit(modules[downIndex >>> 5], downIndex)) & 3;
// 2*2 blocks of modules having same color
if (x >= 1 && (curRow == 0 || curRow == 3) && curRow == nextRow)
result += PENALTY_N2;
}
}
result += finderPenaltyTerminateAndCount(runColor, runX, runHistory) * PENALTY_N3;
}
// Iterate over single columns
for (int x = 0; x < size; x++) {
int runColor = 0;
int runY = 0;
Arrays.fill(runHistory, 0);
for (int y = 0, index = x; y < size; y++, index += size) {
int c = getBit(modules[index >>> 5], index);
if (c == runColor) {
runY++;
if (runY == 5)
result += PENALTY_N1;
else if (runY > 5)
result++;
} else {
finderPenaltyAddHistory(runY, runHistory);
if (runColor == 0)
result += finderPenaltyCountPatterns(runHistory) * PENALTY_N3;
runColor = c;
runY = 1;
}
}
result += finderPenaltyTerminateAndCount(runColor, runY, runHistory) * PENALTY_N3;
}
// Balance of dark and light modules
int total = size * size; // Note that size is odd, so dark/total != 1/2
// Compute the smallest integer k >= 0 such that (45-5k)% <= dark/total <= (55+5k)%
int k = (Math.abs(dark * 20 - total * 10) + total - 1) / total - 1;
result += k * PENALTY_N4;
return result;
}
/*---- Private helper functions ----*/
// 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.
static int getNumDataCodewords(int ver, Ecc ecl) {
return QrTemplate.getNumRawDataModules(ver) / 8
- ECC_CODEWORDS_PER_BLOCK [ecl.ordinal()][ver]
* NUM_ERROR_CORRECTION_BLOCKS[ecl.ordinal()][ver];
}
// Can only be called immediately after a light run is added, and
// returns either 0, 1, or 2. A helper function for getPenaltyScore().
private int finderPenaltyCountPatterns(int[] runHistory) {
int n = runHistory[1];
assert n <= size * 3;
boolean core = n > 0 && runHistory[2] == n && runHistory[3] == n * 3 && runHistory[4] == n && runHistory[5] == n;
return (core && runHistory[0] >= n * 4 && runHistory[6] >= n ? 1 : 0)
+ (core && runHistory[6] >= n * 4 && runHistory[0] >= n ? 1 : 0);
}
// Must be called at the end of a line (row or column) of modules. A helper function for getPenaltyScore().
private int finderPenaltyTerminateAndCount(int currentRunColor, int currentRunLength, int[] runHistory) {
if (currentRunColor == 1) { // Terminate dark run
finderPenaltyAddHistory(currentRunLength, runHistory);
currentRunLength = 0;
}
currentRunLength += size; // Add light border to final run
finderPenaltyAddHistory(currentRunLength, runHistory);
return finderPenaltyCountPatterns(runHistory);
}
// Pushes the given value to the front and drops the last value. A helper function for getPenaltyScore().
private void finderPenaltyAddHistory(int currentRunLength, int[] runHistory) {
if (runHistory[0] == 0)
currentRunLength += size; // Add light border to initial run
System.arraycopy(runHistory, 0, runHistory, 1, runHistory.length - 1);
runHistory[0] = currentRunLength;
}
// Returns 0 or 1 based on the (i mod 32)'th bit of x.
static int getBit(int x, int i) {
return (x >>> i) & 1;
}
/*---- Constants and tables ----*/
/** The minimum version number (1) supported in the QR Code Model 2 standard. */
public static final int MIN_VERSION = 1;
/** The maximum version number (40) supported in the QR Code Model 2 standard. */
public static final int MAX_VERSION = 40;
// For use in getPenaltyScore(), when evaluating which mask is best.
private static final int PENALTY_N1 = 3;
private static final int PENALTY_N2 = 3;
private static final int PENALTY_N3 = 40;
private static final int PENALTY_N4 = 10;
private static final byte[][] ECC_CODEWORDS_PER_BLOCK = {
// 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 final byte[][] NUM_ERROR_CORRECTION_BLOCKS = {
// 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
};
/*---- Public helper enumeration ----*/
/**
* The error correction level in a QR Code symbol.
*/
public enum Ecc {
// Must be declared in ascending order of error protection
// so that the implicit ordinal() and values() work properly
/** The QR Code can tolerate about 7% erroneous codewords. */ LOW(1),
/** The QR Code can tolerate about 15% erroneous codewords. */ MEDIUM(0),
/** The QR Code can tolerate about 25% erroneous codewords. */ QUARTILE(3),
/** The QR Code can tolerate about 30% erroneous codewords. */ HIGH(2);
// In the range 0 to 3 (unsigned 2-bit integer).
final int formatBits;
// Constructor.
private Ecc(int fb) {
formatBits = fb;
}
}
}