/silverlight/multi/qrcode/detector/MultiFinderPatternFinder.cs
C# | 367 lines | 223 code | 37 blank | 107 comment | 45 complexity | 76c9c76d9c07c83d67436b9a975ab34c MD5 | raw file
- /*
- * Copyright 2009 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.
- */
- using System;
- using DecodeHintType = com.google.zxing.DecodeHintType;
- using ReaderException = com.google.zxing.ReaderException;
- using ResultPoint = com.google.zxing.ResultPoint;
- using ResultPointCallback = com.google.zxing.ResultPointCallback;
- using Collections = com.google.zxing.common.Collections;
- using Comparator = com.google.zxing.common.Comparator;
- using BitMatrix = com.google.zxing.common.BitMatrix;
- using FinderPattern = com.google.zxing.qrcode.detector.FinderPattern;
- using FinderPatternFinder = com.google.zxing.qrcode.detector.FinderPatternFinder;
- using FinderPatternInfo = com.google.zxing.qrcode.detector.FinderPatternInfo;
- namespace com.google.zxing.multi.qrcode.detector
- {
-
- /// <summary> <p>This class attempts to find finder patterns in a QR Code. Finder patterns are the square
- /// markers at three corners of a QR Code.</p>
- ///
- /// <p>This class is thread-safe but not reentrant. Each thread must allocate its own object.
- ///
- /// <p>In contrast to {@link FinderPatternFinder}, this class will return an array of all possible
- /// QR code locations in the image.</p>
- ///
- /// <p>Use the TRY_HARDER hint to ask for a more thorough detection.</p>
- ///
- /// </summary>
- /// <author> Sean Owen
- /// </author>
- /// <author> Hannes Erven
- /// </author>
- /// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source
- /// </author>
-
-
- sealed class MultiFinderPatternFinder:FinderPatternFinder
- {
-
- //UPGRADE_NOTE: Final was removed from the declaration of 'EMPTY_RESULT_ARRAY '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
- private static readonly FinderPatternInfo[] EMPTY_RESULT_ARRAY = new FinderPatternInfo[0];
-
- // TODO MIN_MODULE_COUNT and MAX_MODULE_COUNT would be great hints to ask the user for
- // since it limits the number of regions to decode
-
- // max. legal count of modules per QR code edge (177)
- private const float MAX_MODULE_COUNT_PER_EDGE = 180;
- // min. legal count per modules per QR code edge (11)
- private const float MIN_MODULE_COUNT_PER_EDGE = 9;
-
- /// <summary> More or less arbitrary cutoff point for determining if two finder patterns might belong
- /// to the same code if they differ less than DIFF_MODSIZE_CUTOFF_PERCENT percent in their
- /// estimated modules sizes.
- /// </summary>
- private const float DIFF_MODSIZE_CUTOFF_PERCENT = 0.05f;
-
- /// <summary> More or less arbitrary cutoff point for determining if two finder patterns might belong
- /// to the same code if they differ less than DIFF_MODSIZE_CUTOFF pixels/module in their
- /// estimated modules sizes.
- /// </summary>
- private const float DIFF_MODSIZE_CUTOFF = 0.5f;
-
-
- /// <summary> A comparator that orders FinderPatterns by their estimated module size.</summary>
- private class ModuleSizeComparator : Comparator
- {
- public int compare(System.Object center1, System.Object center2)
- {
- float value_Renamed = ((FinderPattern) center2).EstimatedModuleSize - ((FinderPattern) center1).EstimatedModuleSize;
- return value_Renamed < 0.0?- 1:(value_Renamed > 0.0?1:0);
- }
- }
-
- /// <summary> <p>Creates a finder that will search the image for three finder patterns.</p>
- ///
- /// </summary>
- /// <param name="image">image to search
- /// </param>
- internal MultiFinderPatternFinder(BitMatrix image):base(image)
- {
- }
-
- internal MultiFinderPatternFinder(BitMatrix image, ResultPointCallback resultPointCallback):base(image, resultPointCallback)
- {
- }
-
- /// <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;
- }
-
- public FinderPatternInfo[] findMulti(System.Collections.Hashtable 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();
- System.Collections.ArrayList result = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(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;
- }
- }
- }
- }