using System;
/*
* 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.
*/
namespace com.google.zxing.qrcode.encoder
{
/// <summary>
/// @author Satoru Takabayashi
/// @author Daniel Switkin
/// @author Sean Owen
/// </summary>
internal sealed class MaskUtil
{
// Penalty weights from section 6.8.2.1
private const int N1 = 3;
private const int N2 = 3;
private const int N3 = 40;
private const int N4 = 10;
private MaskUtil()
{
// do nothing
}
/// <summary>
/// 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.
/// </summary>
internal static int applyMaskPenaltyRule1(ByteMatrix matrix)
{
return applyMaskPenaltyRule1Internal(matrix, true) + applyMaskPenaltyRule1Internal(matrix, false);
}
/// <summary>
/// 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.
/// </summary>
internal static int applyMaskPenaltyRule2(ByteMatrix matrix)
{
int penalty = 0;
sbyte[][] array = matrix.Array;
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++;
}
}
}
return N2 * penalty;
}
/// <summary>
/// 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).
/// </summary>
internal static int applyMaskPenaltyRule3(ByteMatrix matrix)
{
int penalty = 0;
sbyte[][] array = matrix.Array;
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 += 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;
}
/// <summary>
/// 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.
/// </summary>
internal static int applyMaskPenaltyRule4(ByteMatrix matrix)
{
int numDarkCells = 0;
sbyte[][] array = matrix.Array;
int width = matrix.Width;
int height = matrix.Height;
for (int y = 0; y < height; y++)
{
sbyte[] arrayY = array[y];
for (int x = 0; x < width; x++)
{
if (arrayY[x] == 1)
{
numDarkCells++;
}
}
}
int numTotalCells = matrix.Height * matrix.Width;
double darkRatio = (double) numDarkCells / numTotalCells;
int fivePercentVariances = (int)(Math.Abs(darkRatio - 0.5) * 20.0); // * 100.0 / 5.0
return fivePercentVariances * N4;
}
/// <summary>
/// Return the mask bit for "getMaskPattern" at "x" and "y". See 8.8 of JISX0510:2004 for mask
/// pattern conditions.
/// </summary>
internal static bool 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 = (((int)((uint)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 System.ArgumentException("Invalid mask pattern: " + maskPattern);
}
return intermediate == 0;
}
/// <summary>
/// Helper function for applyMaskPenaltyRule1. We need this for doing this calculation in both
/// vertical and horizontal orders respectively.
/// </summary>
private static int applyMaskPenaltyRule1Internal(ByteMatrix matrix, bool isHorizontal)
{
int penalty = 0;
int iLimit = isHorizontal ? matrix.Height : matrix.Width;
int jLimit = isHorizontal ? matrix.Width : matrix.Height;
sbyte[][] array = matrix.Array;
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;
}
}
}