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reduce new allocations in FinderPatternFinder
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@micjahn
micjahn committed Jan 25, 2025
1 parent 37ecff9 commit 7c2774c
Showing 1 changed file with 57 additions and 80 deletions.
137 changes: 57 additions & 80 deletions Source/lib/qrcode/detector/FinderPatternFinder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,7 @@ public class FinderPatternFinder
private readonly List<FinderPattern> possibleCenters;
private bool hasSkipped;
private readonly int[] crossCheckStateCount;
private readonly int[] stateCount = new int[5];
private readonly ResultPointCallback resultPointCallback;

/// <summary>
Expand Down Expand Up @@ -107,15 +108,16 @@ internal virtual FinderPatternInfo find(IDictionary<DecodeHintType, object> hint
}

bool done = false;
int[] stateCount = new int[5];
BitArray row = null;
for (int i = iSkip - 1; i < maxI && !done; i += iSkip)
{
// Get a row of black/white values
doClearCounts(stateCount);
int currentState = 0;
row = image.getRow(i, row);
for (int j = 0; j < maxJ; j++)
{
if (image[j, i])
if (row[j])
{
// Black pixel
if ((currentState & 1) == 1)
Expand Down Expand Up @@ -292,42 +294,17 @@ protected static bool foundPatternDiagonal(int[] stateCount)
Math.Abs(moduleSize - stateCount[4]) < maxVariance;
}

private int[] CrossCheckStateCount
{
get
{
doClearCounts(crossCheckStateCount);
return crossCheckStateCount;
}
}

/// <summary>
/// sets everything to 0
/// </summary>
/// <param name="counts"></param>
[Obsolete]
protected void clearCounts(int[] counts)
{
doClearCounts(counts);
}

/// <summary>
/// shifts left by 2 index
/// </summary>
/// <param name="stateCount"></param>
[Obsolete]
protected void shiftCounts2(int[] stateCount)
{
doShiftCounts2(stateCount);
}

/// <summary>
/// sets everything to 0
/// </summary>
/// <param name="counts"></param>
protected static void doClearCounts(int[] counts)
protected static void doClearCounts(int[] stateCount)
{
SupportClass.Fill(counts, 0);
stateCount[0] = 0;
stateCount[1] = 0;
stateCount[2] = 0;
stateCount[3] = 0;
stateCount[4] = 0;
}

/// <summary>
Expand All @@ -353,38 +330,38 @@ protected static void doShiftCounts2(int[] stateCount)
/// <returns>true if proportions are withing expected limits</returns>
private bool crossCheckDiagonal(int centerI, int centerJ)
{
int[] stateCount = CrossCheckStateCount;
doClearCounts(crossCheckStateCount);

// Start counting up, left from center finding black center mass
int i = 0;
while (centerI >= i && centerJ >= i && image[centerJ - i, centerI - i])
{
stateCount[2]++;
crossCheckStateCount[2]++;
i++;
}
if (stateCount[2] == 0)
if (crossCheckStateCount[2] == 0)
{
return false;
}

// Continue up, left finding white space
while (centerI >= i && centerJ >= i && !image[centerJ - i, centerI - i])
{
stateCount[1]++;
crossCheckStateCount[1]++;
i++;
}
if (stateCount[1] == 0)
if (crossCheckStateCount[1] == 0)
{
return false;
}

// Continue up, left finding black border
while (centerI >= i && centerJ >= i && image[centerJ - i, centerI - i])
{
stateCount[0]++;
crossCheckStateCount[0]++;
i++;
}
if (stateCount[0] == 0)
if (crossCheckStateCount[0] == 0)
{
return false;
}
Expand All @@ -396,31 +373,31 @@ private bool crossCheckDiagonal(int centerI, int centerJ)
i = 1;
while (centerI + i < maxI && centerJ + i < maxJ && image[centerJ + i, centerI + i])
{
stateCount[2]++;
crossCheckStateCount[2]++;
i++;
}

while (centerI + i < maxI && centerJ + i < maxJ && !image[centerJ + i, centerI + i])
{
stateCount[3]++;
crossCheckStateCount[3]++;
i++;
}
if (stateCount[3] == 0)
if (crossCheckStateCount[3] == 0)
{
return false;
}

while (centerI + i < maxI && centerJ + i < maxJ && image[centerJ + i, centerI + i])
{
stateCount[4]++;
crossCheckStateCount[4]++;
i++;
}
if (stateCount[4] == 0)
if (crossCheckStateCount[4] == 0)
{
return false;
}

return foundPatternDiagonal(stateCount);
return foundPatternDiagonal(crossCheckStateCount);
}

/// <summary>
Expand All @@ -439,35 +416,35 @@ private bool crossCheckDiagonal(int centerI, int centerJ)
private float? crossCheckVertical(int startI, int centerJ, int maxCount, int originalStateCountTotal)
{
int maxI = image.Height;
int[] stateCount = CrossCheckStateCount;
doClearCounts(crossCheckStateCount);

// Start counting up from center
int i = startI;
while (i >= 0 && image[centerJ, i])
{
stateCount[2]++;
crossCheckStateCount[2]++;
i--;
}
if (i < 0)
{
return null;
}
while (i >= 0 && !image[centerJ, i] && stateCount[1] <= maxCount)
while (i >= 0 && !image[centerJ, i] && crossCheckStateCount[1] <= maxCount)
{
stateCount[1]++;
crossCheckStateCount[1]++;
i--;
}
// If already too many modules in this state or ran off the edge:
if (i < 0 || stateCount[1] > maxCount)
if (i < 0 || crossCheckStateCount[1] > maxCount)
{
return null;
}
while (i >= 0 && image[centerJ, i] && stateCount[0] <= maxCount)
while (i >= 0 && image[centerJ, i] && crossCheckStateCount[0] <= maxCount)
{
stateCount[0]++;
crossCheckStateCount[0]++;
i--;
}
if (stateCount[0] > maxCount)
if (crossCheckStateCount[0] > maxCount)
{
return null;
}
Expand All @@ -476,41 +453,41 @@ private bool crossCheckDiagonal(int centerI, int centerJ)
i = startI + 1;
while (i < maxI && image[centerJ, i])
{
stateCount[2]++;
crossCheckStateCount[2]++;
i++;
}
if (i == maxI)
{
return null;
}
while (i < maxI && !image[centerJ, i] && stateCount[3] < maxCount)
while (i < maxI && !image[centerJ, i] && crossCheckStateCount[3] < maxCount)
{
stateCount[3]++;
crossCheckStateCount[3]++;
i++;
}
if (i == maxI || stateCount[3] >= maxCount)
if (i == maxI || crossCheckStateCount[3] >= maxCount)
{
return null;
}
while (i < maxI && image[centerJ, i] && stateCount[4] < maxCount)
while (i < maxI && image[centerJ, i] && crossCheckStateCount[4] < maxCount)
{
stateCount[4]++;
crossCheckStateCount[4]++;
i++;
}
if (stateCount[4] >= maxCount)
if (crossCheckStateCount[4] >= maxCount)
{
return null;
}

// If we found a finder-pattern-like section, but its size is more than 40% different than
// the original, assume it's a false positive
int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];
int stateCountTotal = crossCheckStateCount[0] + crossCheckStateCount[1] + crossCheckStateCount[2] + crossCheckStateCount[3] + crossCheckStateCount[4];
if (5 * Math.Abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal)
{
return null;
}

return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : null;
return foundPatternCross(crossCheckStateCount) ? centerFromEnd(crossCheckStateCount, i) : null;
}

/// <summary> <p>Like {@link #crossCheckVertical(int, int, int, int)}, and in fact is basically identical,
Expand All @@ -520,75 +497,75 @@ private bool crossCheckDiagonal(int centerI, int centerJ)
private float? crossCheckHorizontal(int startJ, int centerI, int maxCount, int originalStateCountTotal)
{
int maxJ = image.Width;
int[] stateCount = CrossCheckStateCount;
doClearCounts(crossCheckStateCount);

int j = startJ;
while (j >= 0 && image[j, centerI])
{
stateCount[2]++;
crossCheckStateCount[2]++;
j--;
}
if (j < 0)
{
return null;
}
while (j >= 0 && !image[j, centerI] && stateCount[1] <= maxCount)
while (j >= 0 && !image[j, centerI] && crossCheckStateCount[1] <= maxCount)
{
stateCount[1]++;
crossCheckStateCount[1]++;
j--;
}
if (j < 0 || stateCount[1] > maxCount)
if (j < 0 || crossCheckStateCount[1] > maxCount)
{
return null;
}
while (j >= 0 && image[j, centerI] && stateCount[0] <= maxCount)
while (j >= 0 && image[j, centerI] && crossCheckStateCount[0] <= maxCount)
{
stateCount[0]++;
crossCheckStateCount[0]++;
j--;
}
if (stateCount[0] > maxCount)
if (crossCheckStateCount[0] > maxCount)
{
return null;
}

j = startJ + 1;
while (j < maxJ && image[j, centerI])
{
stateCount[2]++;
crossCheckStateCount[2]++;
j++;
}
if (j == maxJ)
{
return null;
}
while (j < maxJ && !image[j, centerI] && stateCount[3] < maxCount)
while (j < maxJ && !image[j, centerI] && crossCheckStateCount[3] < maxCount)
{
stateCount[3]++;
crossCheckStateCount[3]++;
j++;
}
if (j == maxJ || stateCount[3] >= maxCount)
if (j == maxJ || crossCheckStateCount[3] >= maxCount)
{
return null;
}
while (j < maxJ && image[j, centerI] && stateCount[4] < maxCount)
while (j < maxJ && image[j, centerI] && crossCheckStateCount[4] < maxCount)
{
stateCount[4]++;
crossCheckStateCount[4]++;
j++;
}
if (stateCount[4] >= maxCount)
if (crossCheckStateCount[4] >= maxCount)
{
return null;
}

// If we found a finder-pattern-like section, but its size is significantly different than
// the original, assume it's a false positive
int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];
int stateCountTotal = crossCheckStateCount[0] + crossCheckStateCount[1] + crossCheckStateCount[2] + crossCheckStateCount[3] + crossCheckStateCount[4];
if (5 * Math.Abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal)
{
return null;
}

return foundPatternCross(stateCount) ? centerFromEnd(stateCount, j) : null;
return foundPatternCross(crossCheckStateCount) ? centerFromEnd(crossCheckStateCount, j) : null;
}

/// <summary>
Expand Down

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