/// <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()
{
int startSize = possibleCenters.Count;
if (startSize < 3)
{
// Couldn't find enough finder patterns
throw ReaderException.Instance;
}
// Filter outlier possibilities whose module size is too different
if (startSize > 3)
{
// But we can only afford to do so if we have at least 4 possibilities to choose from
float totalModuleSize = 0.0f;
for (int i = 0; i < startSize; i++)
{
totalModuleSize += ((FinderPattern)possibleCenters[i]).EstimatedModuleSize;
}
//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 average = totalModuleSize / (float)startSize;
for (int i = 0; i < possibleCenters.Count && possibleCenters.Count > 3; i++)
{
FinderPattern pattern = (FinderPattern)possibleCenters[i];
if (System.Math.Abs(pattern.EstimatedModuleSize - average) > 0.2f * average)
{
possibleCenters.RemoveAt(i);
i--;
}
}
}
if (possibleCenters.Count > 3)
{
// Throw away all but those first size candidate points we found.
Collections.insertionSort(possibleCenters, new CenterComparator());
SupportClass.SetCapacity(possibleCenters, 3);
}
return(new FinderPattern[] { (FinderPattern)possibleCenters[0], (FinderPattern)possibleCenters[1], (FinderPattern)possibleCenters[2] });
}
/// <summary> <p>Detects a Data Matrix Code in an image.</p>
///
/// </summary>
/// <returns> {@link DetectorResult} encapsulating results of detecting a QR Code
/// </returns>
/// <throws> ReaderException if no Data Matrix Code can be found </throws>
public DetectorResult detect()
{
ResultPoint[] cornerPoints = rectangleDetector.detect();
ResultPoint pointA = cornerPoints[0];
ResultPoint pointB = cornerPoints[1];
ResultPoint pointC = cornerPoints[2];
ResultPoint pointD = cornerPoints[3];
// Point A and D are across the diagonal from one another,
// as are B and C. Figure out which are the solid black lines
// by counting transitions
System.Collections.ArrayList transitions = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(4));
transitions.Add(transitionsBetween(pointA, pointB));
transitions.Add(transitionsBetween(pointA, pointC));
transitions.Add(transitionsBetween(pointB, pointD));
transitions.Add(transitionsBetween(pointC, pointD));
Collections.insertionSort(transitions, new ResultPointsAndTransitionsComparator());
// Sort by number of transitions. First two will be the two solid sides; last two
// will be the two alternating black/white sides
ResultPointsAndTransitions lSideOne = (ResultPointsAndTransitions)transitions[0];
ResultPointsAndTransitions lSideTwo = (ResultPointsAndTransitions)transitions[1];
// Figure out which point is their intersection by tallying up the number of times we see the
// endpoints in the four endpoints. One will show up twice.
System.Collections.Hashtable pointCount = System.Collections.Hashtable.Synchronized(new System.Collections.Hashtable());
increment(pointCount, lSideOne.From);
increment(pointCount, lSideOne.To);
increment(pointCount, lSideTwo.From);
increment(pointCount, lSideTwo.To);
ResultPoint maybeTopLeft = null;
ResultPoint bottomLeft = null;
ResultPoint maybeBottomRight = null;
System.Collections.IEnumerator points = pointCount.Keys.GetEnumerator();
//UPGRADE_TODO: Method 'java.util.Enumeration.hasMoreElements' was converted to 'System.Collections.IEnumerator.MoveNext' which has a different behavior. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1073_javautilEnumerationhasMoreElements'"
while (points.MoveNext())
{
//UPGRADE_TODO: Method 'java.util.Enumeration.nextElement' was converted to 'System.Collections.IEnumerator.Current' which has a different behavior. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1073_javautilEnumerationnextElement'"
ResultPoint point = (ResultPoint)points.Current;
System.Int32 value_Renamed = (System.Int32)pointCount[point];
if (value_Renamed == 2)
{
bottomLeft = point; // this is definitely the bottom left, then -- end of two L sides
}
else
{
// Otherwise it's either top left or bottom right -- just assign the two arbitrarily now
if (maybeTopLeft == null)
{
maybeTopLeft = point;
}
else
{
maybeBottomRight = point;
}
}
}
if (maybeTopLeft == null || bottomLeft == null || maybeBottomRight == null)
{
throw ReaderException.Instance;
}
// Bottom left is correct but top left and bottom right might be switched
ResultPoint[] corners = new ResultPoint[] { maybeTopLeft, bottomLeft, maybeBottomRight };
// Use the dot product trick to sort them out
ResultPoint.orderBestPatterns(corners);
// Now we know which is which:
ResultPoint bottomRight = corners[0];
bottomLeft = corners[1];
ResultPoint topLeft = corners[2];
// Which point didn't we find in relation to the "L" sides? that's the top right corner
ResultPoint topRight;
if (!pointCount.ContainsKey(pointA))
{
topRight = pointA;
}
else if (!pointCount.ContainsKey(pointB))
{
topRight = pointB;
}
else if (!pointCount.ContainsKey(pointC))
{
topRight = pointC;
}
else
{
topRight = pointD;
}
// Next determine the dimension by tracing along the top or right side and counting black/white
// transitions. Since we start inside a black module, we should see a number of transitions
// equal to 1 less than the code dimension. Well, actually 2 less, because we are going to
// end on a black module:
// The top right point is actually the corner of a module, which is one of the two black modules
// adjacent to the white module at the top right. Tracing to that corner from either the top left
// or bottom right should work here. The number of transitions could be higher than it should be
// due to noise. So we try both and take the min.
int dimension = System.Math.Min(transitionsBetween(topLeft, topRight).Transitions, transitionsBetween(bottomRight, topRight).Transitions);
if ((dimension & 0x01) == 1)
{
// it can't be odd, so, round... up?
dimension++;
}
dimension += 2;
BitMatrix bits = sampleGrid(image, topLeft, bottomLeft, bottomRight, dimension);
return(new DetectorResult(bits, new ResultPoint[] { pointA, pointB, pointC, pointD }));
}
/// <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()
{
System.Collections.ArrayList 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.
*/
System.Collections.ArrayList results = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(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;
}
