/// <returns> the 3 best {@link FinderPattern}s from our list of candidates. The "best" are
/// those that have been detected at least {@link #CENTER_QUORUM} times, and whose module
/// size differs from the average among those patterns the least
/// </returns>
/// <throws> ReaderException if 3 such finder patterns do not exist </throws>
private FinderPattern[][] selectBestPatterns()
{
var possibleCenters = PossibleCenters;
int size = possibleCenters.Count;
if (size < 3)
{
// Couldn't find enough finder patterns
throw ReaderException.Instance;
}
/*
* Begin HE modifications to safely detect multiple codes of equal size
*/
if (size == 3)
{
return new FinderPattern[][]{new FinderPattern[]{(FinderPattern) possibleCenters[0], (FinderPattern) possibleCenters[1], (FinderPattern) possibleCenters[2]}};
}
// Sort by estimated module size to speed up the upcoming checks
Collections.insertionSort(possibleCenters, new ModuleSizeComparator());
/*
* Now lets start: build a list of tuples of three finder locations that
* - feature similar module sizes
* - are placed in a distance so the estimated module count is within the QR specification
* - have similar distance between upper left/right and left top/bottom finder patterns
* - form a triangle with 90° angle (checked by comparing top right/bottom left distance
* with pythagoras)
*
* Note: we allow each point to be used for more than one code region: this might seem
* counterintuitive at first, but the performance penalty is not that big. At this point,
* we cannot make a good quality decision whether the three finders actually represent
* a QR code, or are just by chance layouted so it looks like there might be a QR code there.
* So, if the layout seems right, lets have the decoder try to decode.
*/
List<FinderPattern[]> results = new List<FinderPattern[]>(10); // holder for the results
for (int i1 = 0; i1 < (size - 2); i1++)
{
FinderPattern p1 = (FinderPattern) possibleCenters[i1];
if (p1 == null)
{
continue;
}
for (int i2 = i1 + 1; i2 < (size - 1); i2++)
{
FinderPattern p2 = (FinderPattern) possibleCenters[i2];
if (p2 == null)
{
continue;
}
// Compare the expected module sizes; if they are really off, skip
float vModSize12 = (p1.EstimatedModuleSize - p2.EstimatedModuleSize) / (System.Math.Min(p1.EstimatedModuleSize, p2.EstimatedModuleSize));
float vModSize12A = System.Math.Abs(p1.EstimatedModuleSize - p2.EstimatedModuleSize);
if (vModSize12A > DIFF_MODSIZE_CUTOFF && vModSize12 >= DIFF_MODSIZE_CUTOFF_PERCENT)
{
// break, since elements are ordered by the module size deviation there cannot be
// any more interesting elements for the given p1.
break;
}
for (int i3 = i2 + 1; i3 < size; i3++)
{
FinderPattern p3 = (FinderPattern) possibleCenters[i3];
if (p3 == null)
{
continue;
}
// Compare the expected module sizes; if they are really off, skip
float vModSize23 = (p2.EstimatedModuleSize - p3.EstimatedModuleSize) / (System.Math.Min(p2.EstimatedModuleSize, p3.EstimatedModuleSize));
float vModSize23A = System.Math.Abs(p2.EstimatedModuleSize - p3.EstimatedModuleSize);
if (vModSize23A > DIFF_MODSIZE_CUTOFF && vModSize23 >= DIFF_MODSIZE_CUTOFF_PERCENT)
{
// break, since elements are ordered by the module size deviation there cannot be
// any more interesting elements for the given p1.
break;
}
FinderPattern[] test = new FinderPattern[]{p1, p2, p3};
ResultPoint.orderBestPatterns(test);
// Calculate the distances: a = topleft-bottomleft, b=topleft-topright, c = diagonal
FinderPatternInfo info = new FinderPatternInfo(test);
float dA = ResultPoint.distance(info.TopLeft, info.BottomLeft);
float dC = ResultPoint.distance(info.TopRight, info.BottomLeft);
float dB = ResultPoint.distance(info.TopLeft, info.TopRight);
// Check the sizes
float estimatedModuleCount = ((dA + dB) / p1.EstimatedModuleSize) / 2;
if (estimatedModuleCount > MAX_MODULE_COUNT_PER_EDGE || estimatedModuleCount < MIN_MODULE_COUNT_PER_EDGE)
{
continue;
}
// Calculate the difference of the edge lengths in percent
float vABBC = System.Math.Abs(((dA - dB) / System.Math.Min(dA, dB)));
if (vABBC >= 0.1f)
{
continue;
}
// Calculate the diagonal length by assuming a 90° angle at topleft
//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
float dCpy = (float) System.Math.Sqrt(dA * dA + dB * dB);
// Compare to the real distance in %
float vPyC = System.Math.Abs(((dC - dCpy) / System.Math.Min(dC, dCpy)));
if (vPyC >= 0.1f)
{
continue;
}
// All tests passed!
results.Add(test);
} // end iterate p3
} // end iterate p2
} // end iterate p1
if (!(results.Count == 0))
{
FinderPattern[][] resultArray = new FinderPattern[results.Count][];
for (int i = 0; i < results.Count; i++)
{
resultArray[i] = (FinderPattern[]) results[i];
}
return resultArray;
}
// Nothing found!
throw ReaderException.Instance;
}
public FinderPatternInfo[] findMulti(System.Collections.Generic.Dictionary<Object, Object> hints)
{
bool tryHarder = hints != null && hints.ContainsKey(DecodeHintType.TRY_HARDER);
BitMatrix image = Image;
int maxI = image.Height;
int maxJ = image.Width;
// We are looking for black/white/black/white/black modules in
// 1:1:3:1:1 ratio; this tracks the number of such modules seen so far
// Let's assume that the maximum version QR Code we support takes up 1/4 the height of the
// image, and then account for the center being 3 modules in size. This gives the smallest
// number of pixels the center could be, so skip this often. When trying harder, look for all
// QR versions regardless of how dense they are.
//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
int iSkip = (int) (maxI / (MAX_MODULES * 4.0f) * 3);
if (iSkip < MIN_SKIP || tryHarder)
{
iSkip = MIN_SKIP;
}
int[] stateCount = new int[5];
for (int i = iSkip - 1; i < maxI; i += iSkip)
{
// Get a row of black/white values
stateCount[0] = 0;
stateCount[1] = 0;
stateCount[2] = 0;
stateCount[3] = 0;
stateCount[4] = 0;
int currentState = 0;
for (int j = 0; j < maxJ; j++)
{
if (image.get_Renamed(j, i))
{
// Black pixel
if ((currentState & 1) == 1)
{
// Counting white pixels
currentState++;
}
stateCount[currentState]++;
}
else
{
// White pixel
if ((currentState & 1) == 0)
{
// Counting black pixels
if (currentState == 4)
{
// A winner?
if (foundPatternCross(stateCount))
{
// Yes
bool confirmed = handlePossibleCenter(stateCount, i, j);
if (!confirmed)
{
do
{
// Advance to next black pixel
j++;
}
while (j < maxJ && !image.get_Renamed(j, i));
j--; // back up to that last white pixel
}
// Clear state to start looking again
currentState = 0;
stateCount[0] = 0;
stateCount[1] = 0;
stateCount[2] = 0;
stateCount[3] = 0;
stateCount[4] = 0;
}
else
{
// No, shift counts back by two
stateCount[0] = stateCount[2];
stateCount[1] = stateCount[3];
stateCount[2] = stateCount[4];
stateCount[3] = 1;
stateCount[4] = 0;
currentState = 3;
}
}
else
{
stateCount[++currentState]++;
}
}
else
{
// Counting white pixels
stateCount[currentState]++;
}
}
} // for j=...
if (foundPatternCross(stateCount))
{
handlePossibleCenter(stateCount, i, maxJ);
} // end if foundPatternCross
} // for i=iSkip-1 ...
FinderPattern[][] patternInfo = selectBestPatterns();
List<FinderPatternInfo> result = new List<FinderPatternInfo>(10);
for (int i = 0; i < patternInfo.Length; i++)
{
FinderPattern[] pattern = patternInfo[i];
ResultPoint.orderBestPatterns(pattern);
result.Add(new FinderPatternInfo(pattern));
}
if ((result.Count == 0))
{
return EMPTY_RESULT_ARRAY;
}
else
{
FinderPatternInfo[] resultArray = new FinderPatternInfo[result.Count];
for (int i = 0; i < result.Count; i++)
{
resultArray[i] = (FinderPatternInfo) result[i];
}
return resultArray;
}
}
protected internal virtual DetectorResult processFinderPatternInfo(FinderPatternInfo info)
{
FinderPattern topLeft = info.TopLeft;
FinderPattern topRight = info.TopRight;
FinderPattern bottomLeft = info.BottomLeft;
float moduleSize = calculateModuleSize(topLeft, topRight, bottomLeft);
if (moduleSize < 1.0f)
{
throw ReaderException.Instance;
}
int dimension = computeDimension(topLeft, topRight, bottomLeft, moduleSize);
Version provisionalVersion = Version.getProvisionalVersionForDimension(dimension);
int modulesBetweenFPCenters = provisionalVersion.DimensionForVersion - 7;
AlignmentPattern alignmentPattern = null;
// Anything above version 1 has an alignment pattern
if (provisionalVersion.AlignmentPatternCenters.Length > 0)
{
// Guess where a "bottom right" finder pattern would have been
float bottomRightX = topRight.X - topLeft.X + bottomLeft.X;
float bottomRightY = topRight.Y - topLeft.Y + bottomLeft.Y;
// Estimate that alignment pattern is closer by 3 modules
// from "bottom right" to known top left location
//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
float correctionToTopLeft = 1.0f - 3.0f / (float) modulesBetweenFPCenters;
//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
int estAlignmentX = (int) (topLeft.X + correctionToTopLeft * (bottomRightX - topLeft.X));
//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
int estAlignmentY = (int) (topLeft.Y + correctionToTopLeft * (bottomRightY - topLeft.Y));
// Kind of arbitrary -- expand search radius before giving up
for (int i = 4; i <= 16; i <<= 1)
{
try
{
//UPGRADE_WARNING: Data types in Visual C# might be different. Verify the accuracy of narrowing conversions. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1042'"
alignmentPattern = findAlignmentInRegion(moduleSize, estAlignmentX, estAlignmentY, (float) i);
break;
}
catch (ReaderException re)
{
// try next round
}
}
// If we didn't find alignment pattern... well try anyway without it
}
PerspectiveTransform transform = createTransform(topLeft, topRight, bottomLeft, alignmentPattern, dimension);
BitMatrix bits = sampleGrid(image, transform, dimension);
ResultPoint[] points;
if (alignmentPattern == null)
{
points = new ResultPoint[]{bottomLeft, topLeft, topRight};
}
else
{
points = new ResultPoint[]{bottomLeft, topLeft, topRight, alignmentPattern};
}
return new DetectorResult(bits, points);
}