com.google.zxing.qrcode.encoder.MaskUtil 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;
/**
* @author Satoru Takabayashi
* @author Daniel Switkin
* @author Sean Owen
*/
final class MaskUtil {
// Penalty weights from section 6.8.2.1
private static final int N1 = 3;
private static final int N2 = 3;
private static final int N3 = 40;
private static final int N4 = 10;
private MaskUtil() {
// do nothing
}
/**
* Apply mask penalty rule 1 and return the penalty. Find repetitive cells with the same color and
* give penalty to them. Example: 00000 or 11111.
*/
static int applyMaskPenaltyRule1(ByteMatrix matrix) {
return applyMaskPenaltyRule1Internal(matrix, true) + applyMaskPenaltyRule1Internal(matrix, false);
}
/**
* Apply mask penalty rule 2 and return the penalty. Find 2x2 blocks with the same color and give
* penalty to them. This is actually equivalent to the spec's rule, which is to find MxN blocks and give a
* penalty proportional to (M-1)x(N-1), because this is the number of 2x2 blocks inside such a block.
*/
static int applyMaskPenaltyRule2(ByteMatrix matrix) {
int penalty = 0;
byte[][] array = matrix.getArray();
int width = matrix.getWidth();
int height = matrix.getHeight();
for (int y = 0; y < height - 1; y++) {
for (int x = 0; x < width - 1; x++) {
int value = array[y][x];
if (value == array[y][x + 1] && value == array[y + 1][x] && value == array[y + 1][x + 1]) {
penalty++;
}
}
}
return N2 * penalty;
}
/**
* Apply mask penalty rule 3 and return the penalty. Find consecutive cells of 00001011101 or
* 10111010000, and give penalty to them. If we find patterns like 000010111010000, we give
* penalties twice (i.e. 40 * 2).
*/
static int applyMaskPenaltyRule3(ByteMatrix matrix) {
int penalty = 0;
byte[][] array = matrix.getArray();
int width = matrix.getWidth();
int height = matrix.getHeight();
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
// Tried to simplify following conditions but failed.
if (x + 6 < width &&
array[y][x] == 1 &&
array[y][x + 1] == 0 &&
array[y][x + 2] == 1 &&
array[y][x + 3] == 1 &&
array[y][x + 4] == 1 &&
array[y][x + 5] == 0 &&
array[y][x + 6] == 1 &&
((x + 10 < width &&
array[y][x + 7] == 0 &&
array[y][x + 8] == 0 &&
array[y][x + 9] == 0 &&
array[y][x + 10] == 0) ||
(x - 4 >= 0 &&
array[y][x - 1] == 0 &&
array[y][x - 2] == 0 &&
array[y][x - 3] == 0 &&
array[y][x - 4] == 0))) {
penalty += N3;
}
if (y + 6 < height &&
array[y][x] == 1 &&
array[y + 1][x] == 0 &&
array[y + 2][x] == 1 &&
array[y + 3][x] == 1 &&
array[y + 4][x] == 1 &&
array[y + 5][x] == 0 &&
array[y + 6][x] == 1 &&
((y + 10 < height &&
array[y + 7][x] == 0 &&
array[y + 8][x] == 0 &&
array[y + 9][x] == 0 &&
array[y + 10][x] == 0) ||
(y - 4 >= 0 &&
array[y - 1][x] == 0 &&
array[y - 2][x] == 0 &&
array[y - 3][x] == 0 &&
array[y - 4][x] == 0))) {
penalty += N3;
}
}
}
return penalty;
}
/**
* Apply mask penalty rule 4 and return the penalty. Calculate the ratio of dark cells and give
* penalty if the ratio is far from 50%. It gives 10 penalty for 5% distance.
*/
static int applyMaskPenaltyRule4(ByteMatrix matrix) {
int numDarkCells = 0;
byte[][] array = matrix.getArray();
int width = matrix.getWidth();
int height = matrix.getHeight();
for (int y = 0; y < height; y++) {
byte[] arrayY = array[y];
for (int x = 0; x < width; x++) {
if (arrayY[x] == 1) {
numDarkCells++;
}
}
}
int numTotalCells = matrix.getHeight() * matrix.getWidth();
double darkRatio = (double) numDarkCells / numTotalCells;
int fivePercentVariances = (int) (Math.abs(darkRatio - 0.5) * 20.0); // * 100.0 / 5.0
return fivePercentVariances * N4;
}
/**
* Return the mask bit for "getMaskPattern" at "x" and "y". See 8.8 of JISX0510:2004 for mask
* pattern conditions.
*/
static boolean getDataMaskBit(int maskPattern, int x, int y) {
int intermediate;
int temp;
switch (maskPattern) {
case 0:
intermediate = (y + x) & 0x1;
break;
case 1:
intermediate = y & 0x1;
break;
case 2:
intermediate = x % 3;
break;
case 3:
intermediate = (y + x) % 3;
break;
case 4:
intermediate = ((y >>> 1) + (x / 3)) & 0x1;
break;
case 5:
temp = y * x;
intermediate = (temp & 0x1) + (temp % 3);
break;
case 6:
temp = y * x;
intermediate = ((temp & 0x1) + (temp % 3)) & 0x1;
break;
case 7:
temp = y * x;
intermediate = ((temp % 3) + ((y + x) & 0x1)) & 0x1;
break;
default:
throw new IllegalArgumentException("Invalid mask pattern: " + maskPattern);
}
return intermediate == 0;
}
/**
* Helper function for applyMaskPenaltyRule1. We need this for doing this calculation in both
* vertical and horizontal orders respectively.
*/
private static int applyMaskPenaltyRule1Internal(ByteMatrix matrix, boolean isHorizontal) {
int penalty = 0;
int iLimit = isHorizontal ? matrix.getHeight() : matrix.getWidth();
int jLimit = isHorizontal ? matrix.getWidth() : matrix.getHeight();
byte[][] array = matrix.getArray();
for (int i = 0; i < iLimit; i++) {
int numSameBitCells = 0;
int prevBit = -1;
for (int j = 0; j < jLimit; j++) {
int bit = isHorizontal ? array[i][j] : array[j][i];
if (bit == prevBit) {
numSameBitCells++;
} else {
if (numSameBitCells >= 5) {
penalty += N1 + (numSameBitCells - 5);
}
numSameBitCells = 1; // Include the cell itself.
prevBit = bit;
}
}
if (numSameBitCells >= 5) {
penalty += N1 + (numSameBitCells - 5);
}
}
return penalty;
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy