com.google.zxing.qrcode.encoder.MatrixUtil Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of core Show documentation
Show all versions of core Show documentation
Core barcode encoding/decoding library
/*
* Copyright 2008 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.zxing.qrcode.encoder;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitArray;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
import com.google.zxing.qrcode.decoder.Version;
/**
* @author [email protected] (Satoru Takabayashi) - creator
* @author [email protected] (Daniel Switkin) - ported from C++
*/
final class MatrixUtil {
private static final int[][] POSITION_DETECTION_PATTERN = {
{1, 1, 1, 1, 1, 1, 1},
{1, 0, 0, 0, 0, 0, 1},
{1, 0, 1, 1, 1, 0, 1},
{1, 0, 1, 1, 1, 0, 1},
{1, 0, 1, 1, 1, 0, 1},
{1, 0, 0, 0, 0, 0, 1},
{1, 1, 1, 1, 1, 1, 1},
};
private static final int[][] POSITION_ADJUSTMENT_PATTERN = {
{1, 1, 1, 1, 1},
{1, 0, 0, 0, 1},
{1, 0, 1, 0, 1},
{1, 0, 0, 0, 1},
{1, 1, 1, 1, 1},
};
// From Appendix E. Table 1, JIS0510X:2004 (p 71). The table was double-checked by komatsu.
private static final int[][] POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE = {
{-1, -1, -1, -1, -1, -1, -1}, // Version 1
{ 6, 18, -1, -1, -1, -1, -1}, // Version 2
{ 6, 22, -1, -1, -1, -1, -1}, // Version 3
{ 6, 26, -1, -1, -1, -1, -1}, // Version 4
{ 6, 30, -1, -1, -1, -1, -1}, // Version 5
{ 6, 34, -1, -1, -1, -1, -1}, // Version 6
{ 6, 22, 38, -1, -1, -1, -1}, // Version 7
{ 6, 24, 42, -1, -1, -1, -1}, // Version 8
{ 6, 26, 46, -1, -1, -1, -1}, // Version 9
{ 6, 28, 50, -1, -1, -1, -1}, // Version 10
{ 6, 30, 54, -1, -1, -1, -1}, // Version 11
{ 6, 32, 58, -1, -1, -1, -1}, // Version 12
{ 6, 34, 62, -1, -1, -1, -1}, // Version 13
{ 6, 26, 46, 66, -1, -1, -1}, // Version 14
{ 6, 26, 48, 70, -1, -1, -1}, // Version 15
{ 6, 26, 50, 74, -1, -1, -1}, // Version 16
{ 6, 30, 54, 78, -1, -1, -1}, // Version 17
{ 6, 30, 56, 82, -1, -1, -1}, // Version 18
{ 6, 30, 58, 86, -1, -1, -1}, // Version 19
{ 6, 34, 62, 90, -1, -1, -1}, // Version 20
{ 6, 28, 50, 72, 94, -1, -1}, // Version 21
{ 6, 26, 50, 74, 98, -1, -1}, // Version 22
{ 6, 30, 54, 78, 102, -1, -1}, // Version 23
{ 6, 28, 54, 80, 106, -1, -1}, // Version 24
{ 6, 32, 58, 84, 110, -1, -1}, // Version 25
{ 6, 30, 58, 86, 114, -1, -1}, // Version 26
{ 6, 34, 62, 90, 118, -1, -1}, // Version 27
{ 6, 26, 50, 74, 98, 122, -1}, // Version 28
{ 6, 30, 54, 78, 102, 126, -1}, // Version 29
{ 6, 26, 52, 78, 104, 130, -1}, // Version 30
{ 6, 30, 56, 82, 108, 134, -1}, // Version 31
{ 6, 34, 60, 86, 112, 138, -1}, // Version 32
{ 6, 30, 58, 86, 114, 142, -1}, // Version 33
{ 6, 34, 62, 90, 118, 146, -1}, // Version 34
{ 6, 30, 54, 78, 102, 126, 150}, // Version 35
{ 6, 24, 50, 76, 102, 128, 154}, // Version 36
{ 6, 28, 54, 80, 106, 132, 158}, // Version 37
{ 6, 32, 58, 84, 110, 136, 162}, // Version 38
{ 6, 26, 54, 82, 110, 138, 166}, // Version 39
{ 6, 30, 58, 86, 114, 142, 170}, // Version 40
};
// Type info cells at the left top corner.
private static final int[][] TYPE_INFO_COORDINATES = {
{8, 0},
{8, 1},
{8, 2},
{8, 3},
{8, 4},
{8, 5},
{8, 7},
{8, 8},
{7, 8},
{5, 8},
{4, 8},
{3, 8},
{2, 8},
{1, 8},
{0, 8},
};
// From Appendix D in JISX0510:2004 (p. 67)
private static final int VERSION_INFO_POLY = 0x1f25; // 1 1111 0010 0101
// From Appendix C in JISX0510:2004 (p.65).
private static final int TYPE_INFO_POLY = 0x537;
private static final int TYPE_INFO_MASK_PATTERN = 0x5412;
private MatrixUtil() {
// do nothing
}
// Set all cells to -1. -1 means that the cell is empty (not set yet).
//
// JAVAPORT: We shouldn't need to do this at all. The code should be rewritten to begin encoding
// with the ByteMatrix initialized all to zero.
static void clearMatrix(ByteMatrix matrix) {
matrix.clear((byte) -1);
}
// Build 2D matrix of QR Code from "dataBits" with "ecLevel", "version" and "getMaskPattern". On
// success, store the result in "matrix" and return true.
static void buildMatrix(BitArray dataBits,
ErrorCorrectionLevel ecLevel,
Version version,
int maskPattern,
ByteMatrix matrix) throws WriterException {
clearMatrix(matrix);
embedBasicPatterns(version, matrix);
// Type information appear with any version.
embedTypeInfo(ecLevel, maskPattern, matrix);
// Version info appear if version >= 7.
maybeEmbedVersionInfo(version, matrix);
// Data should be embedded at end.
embedDataBits(dataBits, maskPattern, matrix);
}
// Embed basic patterns. On success, modify the matrix and return true.
// The basic patterns are:
// - Position detection patterns
// - Timing patterns
// - Dark dot at the left bottom corner
// - Position adjustment patterns, if need be
static void embedBasicPatterns(Version version, ByteMatrix matrix) throws WriterException {
// Let's get started with embedding big squares at corners.
embedPositionDetectionPatternsAndSeparators(matrix);
// Then, embed the dark dot at the left bottom corner.
embedDarkDotAtLeftBottomCorner(matrix);
// Position adjustment patterns appear if version >= 2.
maybeEmbedPositionAdjustmentPatterns(version, matrix);
// Timing patterns should be embedded after position adj. patterns.
embedTimingPatterns(matrix);
}
// Embed type information. On success, modify the matrix.
static void embedTypeInfo(ErrorCorrectionLevel ecLevel, int maskPattern, ByteMatrix matrix)
throws WriterException {
BitArray typeInfoBits = new BitArray();
makeTypeInfoBits(ecLevel, maskPattern, typeInfoBits);
for (int i = 0; i < typeInfoBits.getSize(); ++i) {
// Place bits in LSB to MSB order. LSB (least significant bit) is the last value in
// "typeInfoBits".
boolean bit = typeInfoBits.get(typeInfoBits.getSize() - 1 - i);
// Type info bits at the left top corner. See 8.9 of JISX0510:2004 (p.46).
int[] coordinates = TYPE_INFO_COORDINATES[i];
int x1 = coordinates[0];
int y1 = coordinates[1];
matrix.set(x1, y1, bit);
int x2;
int y2;
if (i < 8) {
// Right top corner.
x2 = matrix.getWidth() - i - 1;
y2 = 8;
} else {
// Left bottom corner.
x2 = 8;
y2 = matrix.getHeight() - 7 + (i - 8);
}
matrix.set(x2, y2, bit);
}
}
// Embed version information if need be. On success, modify the matrix and return true.
// See 8.10 of JISX0510:2004 (p.47) for how to embed version information.
static void maybeEmbedVersionInfo(Version version, ByteMatrix matrix) throws WriterException {
if (version.getVersionNumber() < 7) { // Version info is necessary if version >= 7.
return; // Don't need version info.
}
BitArray versionInfoBits = new BitArray();
makeVersionInfoBits(version, versionInfoBits);
int bitIndex = 6 * 3 - 1; // It will decrease from 17 to 0.
for (int i = 0; i < 6; ++i) {
for (int j = 0; j < 3; ++j) {
// Place bits in LSB (least significant bit) to MSB order.
boolean bit = versionInfoBits.get(bitIndex);
bitIndex--;
// Left bottom corner.
matrix.set(i, matrix.getHeight() - 11 + j, bit);
// Right bottom corner.
matrix.set(matrix.getHeight() - 11 + j, i, bit);
}
}
}
// Embed "dataBits" using "getMaskPattern". On success, modify the matrix and return true.
// For debugging purposes, it skips masking process if "getMaskPattern" is -1.
// See 8.7 of JISX0510:2004 (p.38) for how to embed data bits.
static void embedDataBits(BitArray dataBits, int maskPattern, ByteMatrix matrix)
throws WriterException {
int bitIndex = 0;
int direction = -1;
// Start from the right bottom cell.
int x = matrix.getWidth() - 1;
int y = matrix.getHeight() - 1;
while (x > 0) {
// Skip the vertical timing pattern.
if (x == 6) {
x -= 1;
}
while (y >= 0 && y < matrix.getHeight()) {
for (int i = 0; i < 2; ++i) {
int xx = x - i;
// Skip the cell if it's not empty.
if (!isEmpty(matrix.get(xx, y))) {
continue;
}
boolean bit;
if (bitIndex < dataBits.getSize()) {
bit = dataBits.get(bitIndex);
++bitIndex;
} else {
// Padding bit. If there is no bit left, we'll fill the left cells with 0, as described
// in 8.4.9 of JISX0510:2004 (p. 24).
bit = false;
}
// Skip masking if mask_pattern is -1.
if (maskPattern != -1 && MaskUtil.getDataMaskBit(maskPattern, xx, y)) {
bit = !bit;
}
matrix.set(xx, y, bit);
}
y += direction;
}
direction = -direction; // Reverse the direction.
y += direction;
x -= 2; // Move to the left.
}
// All bits should be consumed.
if (bitIndex != dataBits.getSize()) {
throw new WriterException("Not all bits consumed: " + bitIndex + '/' + dataBits.getSize());
}
}
// Return the position of the most significant bit set (to one) in the "value". The most
// significant bit is position 32. If there is no bit set, return 0. Examples:
// - findMSBSet(0) => 0
// - findMSBSet(1) => 1
// - findMSBSet(255) => 8
static int findMSBSet(int value) {
return 32 - Integer.numberOfLeadingZeros(value);
}
// Calculate BCH (Bose-Chaudhuri-Hocquenghem) code for "value" using polynomial "poly". The BCH
// code is used for encoding type information and version information.
// Example: Calculation of version information of 7.
// f(x) is created from 7.
// - 7 = 000111 in 6 bits
// - f(x) = x^2 + x^1 + x^0
// g(x) is given by the standard (p. 67)
// - g(x) = x^12 + x^11 + x^10 + x^9 + x^8 + x^5 + x^2 + 1
// Multiply f(x) by x^(18 - 6)
// - f'(x) = f(x) * x^(18 - 6)
// - f'(x) = x^14 + x^13 + x^12
// Calculate the remainder of f'(x) / g(x)
// x^2
// __________________________________________________
// g(x) )x^14 + x^13 + x^12
// x^14 + x^13 + x^12 + x^11 + x^10 + x^7 + x^4 + x^2
// --------------------------------------------------
// x^11 + x^10 + x^7 + x^4 + x^2
//
// The remainder is x^11 + x^10 + x^7 + x^4 + x^2
// Encode it in binary: 110010010100
// The return value is 0xc94 (1100 1001 0100)
//
// Since all coefficients in the polynomials are 1 or 0, we can do the calculation by bit
// operations. We don't care if coefficients are positive or negative.
static int calculateBCHCode(int value, int poly) {
if (poly == 0) {
throw new IllegalArgumentException("0 polynomial");
}
// If poly is "1 1111 0010 0101" (version info poly), msbSetInPoly is 13. We'll subtract 1
// from 13 to make it 12.
int msbSetInPoly = findMSBSet(poly);
value <<= msbSetInPoly - 1;
// Do the division business using exclusive-or operations.
while (findMSBSet(value) >= msbSetInPoly) {
value ^= poly << (findMSBSet(value) - msbSetInPoly);
}
// Now the "value" is the remainder (i.e. the BCH code)
return value;
}
// Make bit vector of type information. On success, store the result in "bits" and return true.
// Encode error correction level and mask pattern. See 8.9 of
// JISX0510:2004 (p.45) for details.
static void makeTypeInfoBits(ErrorCorrectionLevel ecLevel, int maskPattern, BitArray bits)
throws WriterException {
if (!QRCode.isValidMaskPattern(maskPattern)) {
throw new WriterException("Invalid mask pattern");
}
int typeInfo = (ecLevel.getBits() << 3) | maskPattern;
bits.appendBits(typeInfo, 5);
int bchCode = calculateBCHCode(typeInfo, TYPE_INFO_POLY);
bits.appendBits(bchCode, 10);
BitArray maskBits = new BitArray();
maskBits.appendBits(TYPE_INFO_MASK_PATTERN, 15);
bits.xor(maskBits);
if (bits.getSize() != 15) { // Just in case.
throw new WriterException("should not happen but we got: " + bits.getSize());
}
}
// Make bit vector of version information. On success, store the result in "bits" and return true.
// See 8.10 of JISX0510:2004 (p.45) for details.
static void makeVersionInfoBits(Version version, BitArray bits) throws WriterException {
bits.appendBits(version.getVersionNumber(), 6);
int bchCode = calculateBCHCode(version.getVersionNumber(), VERSION_INFO_POLY);
bits.appendBits(bchCode, 12);
if (bits.getSize() != 18) { // Just in case.
throw new WriterException("should not happen but we got: " + bits.getSize());
}
}
// Check if "value" is empty.
private static boolean isEmpty(int value) {
return value == -1;
}
private static void embedTimingPatterns(ByteMatrix matrix) {
// -8 is for skipping position detection patterns (size 7), and two horizontal/vertical
// separation patterns (size 1). Thus, 8 = 7 + 1.
for (int i = 8; i < matrix.getWidth() - 8; ++i) {
int bit = (i + 1) % 2;
// Horizontal line.
if (isEmpty(matrix.get(i, 6))) {
matrix.set(i, 6, bit);
}
// Vertical line.
if (isEmpty(matrix.get(6, i))) {
matrix.set(6, i, bit);
}
}
}
// Embed the lonely dark dot at left bottom corner. JISX0510:2004 (p.46)
private static void embedDarkDotAtLeftBottomCorner(ByteMatrix matrix) throws WriterException {
if (matrix.get(8, matrix.getHeight() - 8) == 0) {
throw new WriterException();
}
matrix.set(8, matrix.getHeight() - 8, 1);
}
private static void embedHorizontalSeparationPattern(int xStart,
int yStart,
ByteMatrix matrix) throws WriterException {
for (int x = 0; x < 8; ++x) {
if (!isEmpty(matrix.get(xStart + x, yStart))) {
throw new WriterException();
}
matrix.set(xStart + x, yStart, 0);
}
}
private static void embedVerticalSeparationPattern(int xStart,
int yStart,
ByteMatrix matrix) throws WriterException {
for (int y = 0; y < 7; ++y) {
if (!isEmpty(matrix.get(xStart, yStart + y))) {
throw new WriterException();
}
matrix.set(xStart, yStart + y, 0);
}
}
private static void embedPositionAdjustmentPattern(int xStart, int yStart, ByteMatrix matrix) {
for (int y = 0; y < 5; ++y) {
int[] patternY = POSITION_ADJUSTMENT_PATTERN[y];
for (int x = 0; x < 5; ++x) {
matrix.set(xStart + x, yStart + y, patternY[x]);
}
}
}
private static void embedPositionDetectionPattern(int xStart, int yStart, ByteMatrix matrix) {
for (int y = 0; y < 7; ++y) {
int[] patternY = POSITION_DETECTION_PATTERN[y];
for (int x = 0; x < 7; ++x) {
matrix.set(xStart + x, yStart + y, patternY[x]);
}
}
}
// Embed position detection patterns and surrounding vertical/horizontal separators.
private static void embedPositionDetectionPatternsAndSeparators(ByteMatrix matrix) throws WriterException {
// Embed three big squares at corners.
int pdpWidth = POSITION_DETECTION_PATTERN[0].length;
// Left top corner.
embedPositionDetectionPattern(0, 0, matrix);
// Right top corner.
embedPositionDetectionPattern(matrix.getWidth() - pdpWidth, 0, matrix);
// Left bottom corner.
embedPositionDetectionPattern(0, matrix.getWidth() - pdpWidth, matrix);
// Embed horizontal separation patterns around the squares.
int hspWidth = 8;
// Left top corner.
embedHorizontalSeparationPattern(0, hspWidth - 1, matrix);
// Right top corner.
embedHorizontalSeparationPattern(matrix.getWidth() - hspWidth,
hspWidth - 1, matrix);
// Left bottom corner.
embedHorizontalSeparationPattern(0, matrix.getWidth() - hspWidth, matrix);
// Embed vertical separation patterns around the squares.
int vspSize = 7;
// Left top corner.
embedVerticalSeparationPattern(vspSize, 0, matrix);
// Right top corner.
embedVerticalSeparationPattern(matrix.getHeight() - vspSize - 1, 0, matrix);
// Left bottom corner.
embedVerticalSeparationPattern(vspSize, matrix.getHeight() - vspSize,
matrix);
}
// Embed position adjustment patterns if need be.
private static void maybeEmbedPositionAdjustmentPatterns(Version version, ByteMatrix matrix) {
if (version.getVersionNumber() < 2) { // The patterns appear if version >= 2
return;
}
int index = version.getVersionNumber() - 1;
int[] coordinates = POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE[index];
for (int y : coordinates) {
if (y >= 0) {
for (int x : coordinates) {
if (x >= 0 && isEmpty(matrix.get(x, y))) {
// If the cell is unset, we embed the position adjustment pattern here.
// -2 is necessary since the x/y coordinates point to the center of the pattern, not the
// left top corner.
embedPositionAdjustmentPattern(x - 2, y - 2, matrix);
}
}
}
}
}
}