/*
* Copyright 2007 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.
*/
using System;
using System.Text;
using com.google.zxing;
using com.google.zxing.common;
using com.google.zxing.qrcode.decoder;
using com.google.zxing.qrcode;
namespace com.google.zxing.qrcode.encoder
{
public sealed class MaskUtil
{
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.
public 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.
public static int applyMaskPenaltyRule2(ByteMatrix matrix)
{
int penalty = 0;
sbyte[][] array = matrix.getArray();
int width = matrix.width();
int height = matrix.height();
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 += 3;
}
}
}
return 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).
public static int applyMaskPenaltyRule3(ByteMatrix matrix)
{
int penalty = 0;
sbyte[][] array = matrix.getArray();
int width = matrix.width();
int height = matrix.height();
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 += 40;
}
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 += 40;
}
}
}
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. Examples:
// - 0% => 100
// - 40% => 20
// - 45% => 10
// - 50% => 0
// - 55% => 10
// - 55% => 20
// - 100% => 100
public static int applyMaskPenaltyRule4(ByteMatrix matrix)
{
int numDarkCells = 0;
sbyte[][] array = matrix.getArray();
int width = matrix.width();
int height = matrix.height();
for (int y = 0; y < height; ++y)
{
for (int x = 0; x < width; ++x)
{
if (array[y][x] == 1)
{
numDarkCells += 1;
}
}
}
int numTotalCells = matrix.height() * matrix.width();
double darkRatio = (double)numDarkCells / numTotalCells;
return Math.Abs((int)(darkRatio * 100 - 50)) / 5 * 10;
}
// Return the mask bit for "getMaskPattern" at "x" and "y". See 8.8 of JISX0510:2004 for mask
// pattern conditions.
public static int getDataMaskBit(int maskPattern, int x, int y)
{
if (!QRCode.isValidMaskPattern(maskPattern))
{
throw new ArgumentException("Invalid mask pattern");
}
switch (maskPattern)
{
case 0:
return ((y + x) % 2 == 0) ? 1 : 0;
case 1:
return (y % 2 == 0) ? 1 : 0;
case 2:
return (x % 3 == 0) ? 1 : 0;
case 3:
return ((y + x) % 3 == 0) ? 1 : 0;
case 4:
return (((y / 2) + (x / 3)) % 2 == 0) ? 1 : 0;
case 5:
return (((y * x) % 2) + ((y * x) % 3) == 0) ? 1 : 0;
case 6:
return ((((y * x) % 2) + ((y * x) % 3)) % 2 == 0) ? 1 : 0;
case 7:
return ((((y * x) % 3) + ((y + x) % 2)) % 2 == 0) ? 1 : 0;
}
throw new ArgumentException("invalid mask pattern: " + maskPattern);
}
// Helper function for applyMaskPenaltyRule1. We need this for doing this calculation in both
// vertical and horizontal orders respectively.
private static int applyMaskPenaltyRule1Internal(ByteMatrix matrix, bool isHorizontal)
{
int penalty = 0;
int numSameBitCells = 0;
int prevBit = -1;
// Horizontal mode:
// for (int i = 0; i < matrix.height(); ++i) {
// for (int j = 0; j < matrix.width(); ++j) {
// int bit = matrix.get(i, j);
// Vertical mode:
// for (int i = 0; i < matrix.width(); ++i) {
// for (int j = 0; j < matrix.height(); ++j) {
// int bit = matrix.get(j, i);
int iLimit = isHorizontal ? matrix.height() : matrix.width();
int jLimit = isHorizontal ? matrix.width() : matrix.height();
sbyte[][] array = matrix.getArray();
for (int i = 0; i < iLimit; ++i)
{
for (int j = 0; j < jLimit; ++j)
{
int bit = isHorizontal ? array[i][j] : array[j][i];
if (bit == prevBit)
{
numSameBitCells += 1;
// Found five repetitive cells with the same color (bit).
// We'll give penalty of 3.
if (numSameBitCells == 5)
{
penalty += 3;
}
else if (numSameBitCells > 5)
{
// After five repetitive cells, we'll add the penalty one
// by one.
penalty += 1;
}
}
else
{
numSameBitCells = 1; // Include the cell itself.
prevBit = bit;
}
}
numSameBitCells = 0; // Clear at each row/column.
}
return penalty;
}
}
}