content: /*
   * Copyright 2007 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.
   */
  
  package com.ailiwean.core.zxing.core.qrcode.detector;
  
  
  import android.os.Build;
  
  import com.ailiwean.core.zxing.core.DecodeHintType;
  import com.ailiwean.core.zxing.core.NotFoundException;
  import com.ailiwean.core.zxing.core.ResultPoint;
  import com.ailiwean.core.zxing.core.ResultPointCallback;
  import com.ailiwean.core.zxing.core.common.BitMatrix;
  
  import java.io.Serializable;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Comparator;
  import java.util.List;
  import java.util.Map;
  
  /**
   * <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.
   *
   * @author Sean Owen
   */
  public class FinderPatternFinder {
  
      private static final int CENTER_QUORUM = 2;
      private static final EstimatedModuleComparator moduleComparator = new EstimatedModuleComparator();
      protected static final int MIN_SKIP = 3; // 1 pixel/module times 3 modules/center
      protected static final int MAX_MODULES = 97; // support up to version 20 for mobile clients
  
      private final BitMatrix image;
      private final List<FinderPattern> possibleCenters;
      private boolean hasSkipped;
      private final int[] crossCheckStateCount;
      private final ResultPointCallback resultPointCallback;
  
      /**
       * <p>Creates a finder that will search the image for three finder patterns.</p>
       *
       * @param image image to search
       */
      public FinderPatternFinder(BitMatrix image) {
          this(image, null);
      }
  
      public FinderPatternFinder(BitMatrix image, ResultPointCallback resultPointCallback) {
          this.image = image;
          this.possibleCenters = new ArrayList<>();
          this.crossCheckStateCount = new int[5];
          this.resultPointCallback = resultPointCallback;
      }
  
      protected final BitMatrix getImage() {
          return image;
      }
  
      protected final List<FinderPattern> getPossibleCenters() {
          return possibleCenters;
      }
  
      final FinderPatternInfo find(Map<DecodeHintType, ?> hints) throws NotFoundException {
          boolean tryHarder = hints != null && hints.containsKey(DecodeHintType.TRY_HARDER);
          int maxI = image.getHeight();
          int maxJ = image.getWidth();
          // 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.
          int iSkip = (3 * maxI) / (4 * MAX_MODULES);
          if (iSkip < MIN_SKIP || tryHarder) {
              iSkip = MIN_SKIP;
          }
  
          boolean done = false;
          int[] stateCount = new int[5];
          for (int i = iSkip - 1; i < maxI && !done; i += iSkip) {
              // Get a row of black/white values
              doClearCounts(stateCount);
              int currentState = 0;
              for (int j = 0; j < maxJ; j++) {
                  if (image.get(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
                                  boolean confirmed = handlePossibleCenter(stateCount, i, j);
                                  if (confirmed) {
                                      // Start examining every other line. Checking each line turned out to be too
                                      // expensive and didn't improve performance.
                                      iSkip = 2;
                                      if (hasSkipped) {
                                          done = haveMultiplyConfirmedCenters();
                                      } else {
                                          int rowSkip = findRowSkip();
                                          if (rowSkip > stateCount[2]) {
                                              // Skip rows between row of lower confirmed center
                                              // and top of presumed third confirmed center
                                              // but back up a bit to get a full chance of detecting
                                              // it, entire width of center of finder pattern
  
                                              // Skip by rowSkip, but back off by stateCount[2] (size of last center
                                              // of pattern we saw) to be conservative, and also back off by iSkip which
                                              // is about to be re-added
                                              i += rowSkip - stateCount[2] - iSkip;
                                              j = maxJ - 1;
                                          }
                                      }
                                  } else {
                                      doShiftCounts2(stateCount);
                                      currentState = 3;
                                      continue;
                                  }
                                  // Clear state to start looking again
                                  currentState = 0;
                                  doClearCounts(stateCount);
                              } else { // No, shift counts back by two
                                  doShiftCounts2(stateCount);
                                  currentState = 3;
                              }
                          } else {
                              stateCount[++currentState]++;
                          }
                      } else { // Counting white pixels
                          stateCount[currentState]++;
                      }
                  }
              }
              if (foundPatternCross(stateCount)) {
                  boolean confirmed = handlePossibleCenter(stateCount, i, maxJ);
                  if (confirmed) {
                      iSkip = stateCount[0];
                      if (hasSkipped) {
                          // Found a third one
                          done = haveMultiplyConfirmedCenters();
                      }
                  }
              }
          }
  
          FinderPattern[] patternInfo = selectBestPatterns();
          ResultPoint.orderBestPatterns(patternInfo);
  
          return new FinderPatternInfo(patternInfo);
      }
  
      /**
       * Given a count of black/white/black/white/black pixels just seen and an end position,
       * figures the location of the center of this run.
       */
      private static float centerFromEnd(int[] stateCount, int end) {
          return (end - stateCount[4] - stateCount[3]) - stateCount[2] / 2.0f;
      }
  
      /**
       * @param stateCount count of black/white/black/white/black pixels just read
       * @return true iff the proportions of the counts is close enough to the 1/1/3/1/1 ratios
       * used by finder patterns to be considered a match
       */
      protected static boolean foundPatternCross(int[] stateCount) {
          int totalModuleSize = 0;
          for (int i = 0; i < 5; i++) {
              int count = stateCount[i];
              if (count == 0) {
                  return false;
              }
              totalModuleSize += count;
          }
          if (totalModuleSize < 7) {
              return false;
          }
          float moduleSize = totalModuleSize / 7.0f;
          float maxVariance = moduleSize / 2.0f;
          // Allow less than 50% variance from 1-1-3-1-1 proportions
          return
                  Math.abs(moduleSize - stateCount[0]) < maxVariance &&
                          Math.abs(moduleSize - stateCount[1]) < maxVariance &&
                          Math.abs(3.0f * moduleSize - stateCount[2]) < 3 * maxVariance &&
                          Math.abs(moduleSize - stateCount[3]) < maxVariance &&
                          Math.abs(moduleSize - stateCount[4]) < maxVariance;
      }
  
      /**
       * @param stateCount count of black/white/black/white/black pixels just read
       * @return true iff the proportions of the counts is close enough to the 1/1/3/1/1 ratios
       * used by finder patterns to be considered a match
       */
      protected static boolean foundPatternDiagonal(int[] stateCount) {
          int totalModuleSize = 0;
          for (int i = 0; i < 5; i++) {
              int count = stateCount[i];
              if (count == 0) {
                  return false;
              }
              totalModuleSize += count;
          }
          if (totalModuleSize < 7) {
              return false;
          }
          float moduleSize = totalModuleSize / 7.0f;
          float maxVariance = moduleSize / 1.333f;
          // Allow less than 75% variance from 1-1-3-1-1 proportions
          return
                  Math.abs(moduleSize - stateCount[0]) < maxVariance &&
                          Math.abs(moduleSize - stateCount[1]) < maxVariance &&
                          Math.abs(3.0f * moduleSize - stateCount[2]) < 3 * maxVariance &&
                          Math.abs(moduleSize - stateCount[3]) < maxVariance &&
                          Math.abs(moduleSize - stateCount[4]) < maxVariance;
      }
  
      private int[] getCrossCheckStateCount() {
          doClearCounts(crossCheckStateCount);
          return crossCheckStateCount;
      }
  
      @Deprecated
      protected final void clearCounts(int[] counts) {
          doClearCounts(counts);
      }
  
      @Deprecated
      protected final void shiftCounts2(int[] stateCount) {
          doShiftCounts2(stateCount);
      }
  
      protected static void doClearCounts(int[] counts) {
          Arrays.fill(counts, 0);
      }
  
      protected static void doShiftCounts2(int[] stateCount) {
          stateCount[0] = stateCount[2];
          stateCount[1] = stateCount[3];
          stateCount[2] = stateCount[4];
          stateCount[3] = 1;
          stateCount[4] = 0;
      }
  
      /**
       * After a vertical and horizontal scan finds a potential finder pattern, this method
       * "cross-cross-cross-checks" by scanning down diagonally through the center of the possible
       * finder pattern to see if the same proportion is detected.
       *
       * @param centerI row where a finder pattern was detected
       * @param centerJ center of the section that appears to cross a finder pattern
       * @return true if proportions are withing expected limits
       */
      private boolean crossCheckDiagonal(int centerI, int centerJ) {
          int[] stateCount = getCrossCheckStateCount();
  
          // Start counting up, left from center finding black center mass
          int i = 0;
          while (centerI >= i && centerJ >= i && image.get(centerJ - i, centerI - i)) {
              stateCount[2]++;
              i++;
          }
          if (stateCount[2] == 0) {
              return false;
          }
  
          // Continue up, left finding white space
          while (centerI >= i && centerJ >= i && !image.get(centerJ - i, centerI - i)) {
              stateCount[1]++;
              i++;
          }
          if (stateCount[1] == 0) {
              return false;
          }
  
          // Continue up, left finding black border
          while (centerI >= i && centerJ >= i && image.get(centerJ - i, centerI - i)) {
              stateCount[0]++;
              i++;
          }
          if (stateCount[0] == 0) {
              return false;
          }
  
          int maxI = image.getHeight();
          int maxJ = image.getWidth();
  
          // Now also count down, right from center
          i = 1;
          while (centerI + i < maxI && centerJ + i < maxJ && image.get(centerJ + i, centerI + i)) {
              stateCount[2]++;
              i++;
          }
  
          while (centerI + i < maxI && centerJ + i < maxJ && !image.get(centerJ + i, centerI + i)) {
              stateCount[3]++;
              i++;
          }
          if (stateCount[3] == 0) {
              return false;
          }
  
          while (centerI + i < maxI && centerJ + i < maxJ && image.get(centerJ + i, centerI + i)) {
              stateCount[4]++;
              i++;
          }
          if (stateCount[4] == 0) {
              return false;
          }
  
          return foundPatternDiagonal(stateCount);
      }
  
      /**
       * <p>After a horizontal scan finds a potential finder pattern, this method
       * "cross-checks" by scanning down vertically through the center of the possible
       * finder pattern to see if the same proportion is detected.</p>
       *
       * @param startI   row where a finder pattern was detected
       * @param centerJ  center of the section that appears to cross a finder pattern
       * @param maxCount maximum reasonable number of modules that should be
       *                 observed in any reading state, based on the results of the horizontal scan
       * @return vertical center of finder pattern, or {@link Float#NaN} if not found
       */
      private float crossCheckVertical(int startI, int centerJ, int maxCount,
                                       int originalStateCountTotal) {
          BitMatrix image = this.image;
  
          int maxI = image.getHeight();
          int[] stateCount = getCrossCheckStateCount();
  
          // Start counting up from center
          int i = startI;
          while (i >= 0 && image.get(centerJ, i)) {
              stateCount[2]++;
              i--;
          }
          if (i < 0) {
              return Float.NaN;
          }
          while (i >= 0 && !image.get(centerJ, i) && stateCount[1] <= maxCount) {
              stateCount[1]++;
              i--;
          }
          // If already too many modules in this state or ran off the edge:
          if (i < 0 || stateCount[1] > maxCount) {
              return Float.NaN;
          }
          while (i >= 0 && image.get(centerJ, i) && stateCount[0] <= maxCount) {
              stateCount[0]++;
              i--;
          }
          if (stateCount[0] > maxCount) {
              return Float.NaN;
          }
  
          // Now also count down from center
          i = startI + 1;
          while (i < maxI && image.get(centerJ, i)) {
              stateCount[2]++;
              i++;
          }
          if (i == maxI) {
              return Float.NaN;
          }
          while (i < maxI && !image.get(centerJ, i) && stateCount[3] < maxCount) {
              stateCount[3]++;
              i++;
          }
          if (i == maxI || stateCount[3] >= maxCount) {
              return Float.NaN;
          }
          while (i < maxI && image.get(centerJ, i) && stateCount[4] < maxCount) {
              stateCount[4]++;
              i++;
          }
          if (stateCount[4] >= maxCount) {
              return Float.NaN;
          }
  
          // 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];
          if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= 2 * originalStateCountTotal) {
              return Float.NaN;
          }
  
          return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : Float.NaN;
      }
  
      /**
       * <p>Like {@link #crossCheckVertical(int, int, int, int)}, and in fact is basically identical,
       * except it reads horizontally instead of vertically. This is used to cross-cross
       * check a vertical cross check and locate the real center of the alignment pattern.</p>
       */
      private float crossCheckHorizontal(int startJ, int centerI, int maxCount,
                                         int originalStateCountTotal) {
          BitMatrix image = this.image;
  
          int maxJ = image.getWidth();
          int[] stateCount = getCrossCheckStateCount();
  
          int j = startJ;
          while (j >= 0 && image.get(j, centerI)) {
              stateCount[2]++;
              j--;
          }
          if (j < 0) {
              return Float.NaN;
          }
          while (j >= 0 && !image.get(j, centerI) && stateCount[1] <= maxCount) {
              stateCount[1]++;
              j--;
          }
          if (j < 0 || stateCount[1] > maxCount) {
              return Float.NaN;
          }
          while (j >= 0 && image.get(j, centerI) && stateCount[0] <= maxCount) {
              stateCount[0]++;
              j--;
          }
          if (stateCount[0] > maxCount) {
              return Float.NaN;
          }
  
          j = startJ + 1;
          while (j < maxJ && image.get(j, centerI)) {
              stateCount[2]++;
              j++;
          }
          if (j == maxJ) {
              return Float.NaN;
          }
          while (j < maxJ && !image.get(j, centerI) && stateCount[3] < maxCount) {
              stateCount[3]++;
              j++;
          }
          if (j == maxJ || stateCount[3] >= maxCount) {
              return Float.NaN;
          }
          while (j < maxJ && image.get(j, centerI) && stateCount[4] < maxCount) {
              stateCount[4]++;
              j++;
          }
          if (stateCount[4] >= maxCount) {
              return Float.NaN;
          }
  
          // 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];
          if (5 * Math.abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {
              return Float.NaN;
          }
  
          return foundPatternCross(stateCount) ? centerFromEnd(stateCount, j) : Float.NaN;
      }
  
      /**
       * @param stateCount  reading state module counts from horizontal scan
       * @param i           row where finder pattern may be found
       * @param j           end of possible finder pattern in row
       * @param pureBarcode ignored
       * @return true if a finder pattern candidate was found this time
       * @see #handlePossibleCenter(int[], int, int)
       * @deprecated only exists for backwards compatibility
       */
      @Deprecated
      protected final boolean handlePossibleCenter(int[] stateCount, int i, int j, boolean pureBarcode) {
          return handlePossibleCenter(stateCount, i, j);
      }
  
      /**
       * <p>This is called when a horizontal scan finds a possible alignment pattern. It will
       * cross check with a vertical scan, and if successful, will, ah, cross-cross-check
       * with another horizontal scan. This is needed primarily to locate the real horizontal
       * center of the pattern in cases of extreme skew.
       * And then we cross-cross-cross check with another diagonal scan.</p>
       *
       * <p>If that succeeds the finder pattern location is added to a list that tracks
       * the number of times each location has been nearly-matched as a finder pattern.
       * Each additional find is more evidence that the location is in fact a finder
       * pattern center
       *
       * @param stateCount reading state module counts from horizontal scan
       * @param i          row where finder pattern may be found
       * @param j          end of possible finder pattern in row
       * @return true if a finder pattern candidate was found this time
       */
      protected final boolean handlePossibleCenter(int[] stateCount, int i, int j) {
          int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] +
                  stateCount[4];
          float centerJ = centerFromEnd(stateCount, j);
          float centerI = crossCheckVertical(i, (int) centerJ, stateCount[2], stateCountTotal);
          if (!Float.isNaN(centerI)) {
              // Re-cross check
              centerJ = crossCheckHorizontal((int) centerJ, (int) centerI, stateCount[2], stateCountTotal);
              if (!Float.isNaN(centerJ) && crossCheckDiagonal((int) centerI, (int) centerJ)) {
                  float estimatedModuleSize = stateCountTotal / 7.0f;
                  boolean found = false;
                  for (int index = 0; index < possibleCenters.size(); index++) {
                      FinderPattern center = possibleCenters.get(index);
                      // Look for about the same center and module size:
                      if (center.aboutEquals(estimatedModuleSize, centerI, centerJ)) {
                          possibleCenters.set(index, center.combineEstimate(centerI, centerJ, estimatedModuleSize));
                          found = true;
                          break;
                      }
                  }
                  if (!found) {
                      FinderPattern point = new FinderPattern(centerJ, centerI, estimatedModuleSize);
                      possibleCenters.add(point);
                      if (resultPointCallback != null) {
                          resultPointCallback.foundPossibleResultPoint(point);
                      }
                  }
                  return true;
              }
          }
          return false;
      }
  
      /**
       * @return number of rows we could safely skip during scanning, based on the first
       * two finder patterns that have been located. In some cases their position will
       * allow us to infer that the third pattern must lie below a certain point farther
       * down in the image.
       */
      private int findRowSkip() {
          int max = possibleCenters.size();
          if (max <= 1) {
              return 0;
          }
          ResultPoint firstConfirmedCenter = null;
          for (FinderPattern center : possibleCenters) {
              if (center.getCount() >= CENTER_QUORUM) {
                  if (firstConfirmedCenter == null) {
                      firstConfirmedCenter = center;
                  } else {
                      // We have two confirmed centers
                      // How far down can we skip before resuming looking for the next
                      // pattern? In the worst case, only the difference between the
                      // difference in the x / y coordinates of the two centers.
                      // This is the case where you find top left last.
                      hasSkipped = true;
                      return (int) (Math.abs(firstConfirmedCenter.getX() - center.getX()) -
                              Math.abs(firstConfirmedCenter.getY() - center.getY())) / 2;
                  }
              }
          }
          return 0;
      }
  
      /**
       * @return true iff we have found at least 3 finder patterns that have been detected
       * at least {@link #CENTER_QUORUM} times each, and, the estimated module size of the
       * candidates is "pretty similar"
       */
      private boolean haveMultiplyConfirmedCenters() {
          int confirmedCount = 0;
          float totalModuleSize = 0.0f;
          int max = possibleCenters.size();
          for (FinderPattern pattern : possibleCenters) {
              if (pattern.getCount() >= CENTER_QUORUM) {
                  confirmedCount++;
                  totalModuleSize += pattern.getEstimatedModuleSize();
              }
          }
          if (confirmedCount < 3) {
              return false;
          }
          // OK, we have at least 3 confirmed centers, but, it's possible that one is a "false positive"
          // and that we need to keep looking. We detect this by asking if the estimated module sizes
          // vary too much. We arbitrarily say that when the total deviation from average exceeds
          // 5% of the total module size estimates, it's too much.
          float average = totalModuleSize / max;
          float totalDeviation = 0.0f;
          for (FinderPattern pattern : possibleCenters) {
              totalDeviation += Math.abs(pattern.getEstimatedModuleSize() - average);
          }
          return totalDeviation <= 0.05f * totalModuleSize;
      }
  
      /**
       * Get square of distance between a and b.
       */
      private static double squaredDistance(FinderPattern a, FinderPattern b) {
          double x = a.getX() - b.getX();
          double y = a.getY() - b.getY();
          return x * x + y * y;
      }
  
      /**
       * @return the 3 best {@link FinderPattern}s from our list of candidates. The "best" are
       * those have similar module size and form a shape closer to a isosceles right triangle.
       * @throws NotFoundException if 3 such finder patterns do not exist
       */
      private FinderPattern[] selectBestPatterns() throws NotFoundException {
  
          int startSize = possibleCenters.size();
          if (startSize < 3) {
              // Couldn't find enough finder patterns
              throw NotFoundException.getNotFoundInstance();
          }
  
          if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
              possibleCenters.sort(moduleComparator);
          }
  
          double distortion = Double.MAX_VALUE;
          FinderPattern[] bestPatterns = new FinderPattern[3];
  
          for (int i = 0; i < possibleCenters.size() - 2; i++) {
              FinderPattern fpi = possibleCenters.get(i);
              float minModuleSize = fpi.getEstimatedModuleSize();
  
              for (int j = i + 1; j < possibleCenters.size() - 1; j++) {
                  FinderPattern fpj = possibleCenters.get(j);
                  double squares0 = squaredDistance(fpi, fpj);
  
                  for (int k = j + 1; k < possibleCenters.size(); k++) {
                      FinderPattern fpk = possibleCenters.get(k);
                      float maxModuleSize = fpk.getEstimatedModuleSize();
                      if (maxModuleSize > minModuleSize * 1.4f) {
                          // module size is not similar
                          continue;
                      }
  
                      double a = squares0;
                      double b = squaredDistance(fpj, fpk);
                      double c = squaredDistance(fpi, fpk);
  
                      // sorts ascending - inlined
                      if (a < b) {
                          if (b > c) {
                              if (a < c) {
                                  double temp = b;
                                  b = c;
                                  c = temp;
                              } else {
                                  double temp = a;
                                  a = c;
                                  c = b;
                                  b = temp;
                              }
                          }
                      } else {
                          if (b < c) {
                              if (a < c) {
                                  double temp = a;
                                  a = b;
                                  b = temp;
                              } else {
                                  double temp = a;
                                  a = b;
                                  b = c;
                                  c = temp;
                              }
                          } else {
                              double temp = a;
                              a = c;
                              c = temp;
                          }
                      }
  
                      // a^2 + b^2 = c^2 (Pythagorean theorem), and a = b (isosceles triangle).
                      // Since any right triangle satisfies the formula c^2 - b^2 - a^2 = 0,
                      // we need to check both two equal sides separately.
                      // The value of |c^2 - 2 * b^2| + |c^2 - 2 * a^2| increases as dissimilarity
                      // from isosceles right triangle.
                      double d = Math.abs(c - 2 * b) + Math.abs(c - 2 * a);
                      if (d < distortion) {
                          distortion = d;
                          bestPatterns[0] = fpi;
                          bestPatterns[1] = fpj;
                          bestPatterns[2] = fpk;
                      }
                  }
              }
          }
  
          if (distortion == Double.MAX_VALUE) {
              throw NotFoundException.getNotFoundInstance();
          }
  
          return bestPatterns;
      }
  
      /**
       * <p>Orders by {@link FinderPattern#getEstimatedModuleSize()}</p>
       */
      private static final class EstimatedModuleComparator implements Comparator<FinderPattern>, Serializable {
          @Override
          public int compare(FinderPattern center1, FinderPattern center2) {
              return Float.compare(center1.getEstimatedModuleSize(), center2.getEstimatedModuleSize());
          }
      }
  
  }
  