/// <summary> <p>Estimates module size (pixels in a module) based on the Start and End
/// finder patterns.</p>
///
/// </summary>
/// <param name="vertices">an array of vertices:
/// vertices[0] x, y top left barcode
/// vertices[1] x, y bottom left barcode
/// vertices[2] x, y top right barcode
/// vertices[3] x, y bottom right barcode
/// vertices[4] x, y top left codeword area
/// vertices[5] x, y bottom left codeword area
/// vertices[6] x, y top right codeword area
/// vertices[7] x, y bottom right codeword area
/// </param>
/// <returns> the module size.
/// </returns>
private static float computeModuleWidth(ResultPoint[] vertices)
{
float pixels1 = ResultPoint.distance(vertices[0], vertices[4]);
float pixels2 = ResultPoint.distance(vertices[1], vertices[5]);
float moduleWidth1 = (pixels1 + pixels2) / (17 * 2.0f);
float pixels3 = ResultPoint.distance(vertices[6], vertices[2]);
float pixels4 = ResultPoint.distance(vertices[7], vertices[3]);
float moduleWidth2 = (pixels3 + pixels4) / (18 * 2.0f);
return((moduleWidth1 + moduleWidth2) / 2.0f);
}
/// <summary> Computes the dimension (number of modules in a row) of the PDF417 Code
/// based on vertices of the codeword area and estimated module size.
///
/// </summary>
/// <param name="topLeft"> of codeword area
/// </param>
/// <param name="topRight"> of codeword area
/// </param>
/// <param name="bottomLeft"> of codeword area
/// </param>
/// <param name="bottomRight">of codeword are
/// </param>
/// <param name="moduleWidth">estimated module size
/// </param>
/// <returns> the number of modules in a row.
/// </returns>
private static int computeDimension(ResultPoint topLeft, ResultPoint topRight, ResultPoint bottomLeft, ResultPoint bottomRight, float moduleWidth)
{
int topRowDimension = round(ResultPoint.distance(topLeft, topRight) / moduleWidth);
int bottomRowDimension = round(ResultPoint.distance(bottomLeft, bottomRight) / moduleWidth);
return(((((topRowDimension + bottomRowDimension) >> 1) + 8) / 17) * 17);
/*
* int topRowDimension = round(ResultPoint.distance(topLeft,
* topRight)); //moduleWidth); int bottomRowDimension =
* round(ResultPoint.distance(bottomLeft, bottomRight)); //
* moduleWidth); int dimension = ((topRowDimension + bottomRowDimension)
* >> 1); // Round up to nearest 17 modules i.e. there are 17 modules per
* codeword //int dimension = ((((topRowDimension + bottomRowDimension) >>
* 1) + 8) / 17) * 17; return dimension;
*/
}
/// <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;
}
