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 com.ailiwean.core.zxing.core.DecodeHintType;
  import com.ailiwean.core.zxing.core.FormatException;
  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 com.ailiwean.core.zxing.core.common.DetectorResult;
  import com.ailiwean.core.zxing.core.common.GridSampler;
  import com.ailiwean.core.zxing.core.common.PerspectiveTransform;
  import com.ailiwean.core.zxing.core.common.detector.MathUtils;
  import com.ailiwean.core.zxing.core.qrcode.decoder.Version;
  
  import java.util.Map;
  
  /**
   * <p>Encapsulates logic that can detect a QR Code in an image, even if the QR Code
   * is rotated or skewed, or partially obscured.</p>
   *
   * @author Sean Owen
   */
  public class Detector {
  
      private final BitMatrix image;
      private ResultPointCallback resultPointCallback;
  
      public Detector(BitMatrix image) {
          this.image = image;
      }
  
      protected final BitMatrix getImage() {
          return image;
      }
  
      protected final ResultPointCallback getResultPointCallback() {
          return resultPointCallback;
      }
  
      /**
       * <p>Detects a QR Code in an image.</p>
       *
       * @return {@link DetectorResult} encapsulating results of detecting a QR Code
       * @throws NotFoundException if QR Code cannot be found
       * @throws FormatException   if a QR Code cannot be decoded
       */
      public DetectorResult detect() throws NotFoundException, FormatException {
          return detect(null);
      }
  
      /**
       * <p>Detects a QR Code in an image.</p>
       *
       * @param hints optional hints to detector
       * @return {@link DetectorResult} encapsulating results of detecting a QR Code
       * @throws NotFoundException if QR Code cannot be found
       * @throws FormatException   if a QR Code cannot be decoded
       */
      public final DetectorResult detect(Map<DecodeHintType, ?> hints) throws NotFoundException, FormatException {
  
          resultPointCallback = hints == null ? null :
                  (ResultPointCallback) hints.get(DecodeHintType.NEED_RESULT_POINT_CALLBACK);
  
          FinderPatternFinder finder = new FinderPatternFinder(image, resultPointCallback);
          FinderPatternInfo info = finder.find(hints);
  
          return processFinderPatternInfo(info);
      }
  
      protected final DetectorResult processFinderPatternInfo(FinderPatternInfo info)
              throws NotFoundException, FormatException {
  
          FinderPattern topLeft = info.getTopLeft();
          FinderPattern topRight = info.getTopRight();
          FinderPattern bottomLeft = info.getBottomLeft();
  
          float moduleSize = calculateModuleSize(topLeft, topRight, bottomLeft);
          if (moduleSize < 1.0f) {
              throw NotFoundException.getNotFoundInstance();
          }
          int dimension = computeDimension(topLeft, topRight, bottomLeft, moduleSize);
          Version provisionalVersion = Version.getProvisionalVersionForDimension(dimension);
          int modulesBetweenFPCenters = provisionalVersion.getDimensionForVersion() - 7;
  
          AlignmentPattern alignmentPattern = null;
          // Anything above version 1 has an alignment pattern
          if (provisionalVersion.getAlignmentPatternCenters().length > 0) {
  
              // Guess where a "bottom right" finder pattern would have been
              float bottomRightX = topRight.getX() - topLeft.getX() + bottomLeft.getX();
              float bottomRightY = topRight.getY() - topLeft.getY() + bottomLeft.getY();
  
              // Estimate that alignment pattern is closer by 3 modules
              // from "bottom right" to known top left location
              float correctionToTopLeft = 1.0f - 3.0f / modulesBetweenFPCenters;
              int estAlignmentX = (int) (topLeft.getX() + correctionToTopLeft * (bottomRightX - topLeft.getX()));
              int estAlignmentY = (int) (topLeft.getY() + correctionToTopLeft * (bottomRightY - topLeft.getY()));
              // Kind of arbitrary -- expand search radius before giving up
              for (int i = 4; i <= 16; i <<= 1) {
                  try {
                      alignmentPattern = findAlignmentInRegion(moduleSize,
                              estAlignmentX,
                              estAlignmentY,
                              i);
                      break;
                  } catch (NotFoundException 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);
      }
  
      private static PerspectiveTransform createTransform(ResultPoint topLeft,
                                                          ResultPoint topRight,
                                                          ResultPoint bottomLeft,
                                                          ResultPoint alignmentPattern,
                                                          int dimension) {
          float dimMinusThree = dimension - 3.5f;
          float bottomRightX;
          float bottomRightY;
          float sourceBottomRightX;
          float sourceBottomRightY;
          if (alignmentPattern != null) {
              bottomRightX = alignmentPattern.getX();
              bottomRightY = alignmentPattern.getY();
              sourceBottomRightX = dimMinusThree - 3.0f;
              sourceBottomRightY = sourceBottomRightX;
          } else {
              // Don't have an alignment pattern, just make up the bottom-right point
              bottomRightX = (topRight.getX() - topLeft.getX()) + bottomLeft.getX();
              bottomRightY = (topRight.getY() - topLeft.getY()) + bottomLeft.getY();
              sourceBottomRightX = dimMinusThree;
              sourceBottomRightY = dimMinusThree;
          }
  
          return PerspectiveTransform.quadrilateralToQuadrilateral(
                  3.5f,
                  3.5f,
                  dimMinusThree,
                  3.5f,
                  sourceBottomRightX,
                  sourceBottomRightY,
                  3.5f,
                  dimMinusThree,
                  topLeft.getX(),
                  topLeft.getY(),
                  topRight.getX(),
                  topRight.getY(),
                  bottomRightX,
                  bottomRightY,
                  bottomLeft.getX(),
                  bottomLeft.getY());
      }
  
      private static BitMatrix sampleGrid(BitMatrix image,
                                          PerspectiveTransform transform,
                                          int dimension) throws NotFoundException {
  
          GridSampler sampler = GridSampler.getInstance();
          return sampler.sampleGrid(image, dimension, dimension, transform);
      }
  
      /**
       * <p>Computes the dimension (number of modules on a size) of the QR Code based on the position
       * of the finder patterns and estimated module size.</p>
       */
      private static int computeDimension(ResultPoint topLeft,
                                          ResultPoint topRight,
                                          ResultPoint bottomLeft,
                                          float moduleSize) throws NotFoundException {
          int tltrCentersDimension = MathUtils.round(ResultPoint.distance(topLeft, topRight) / moduleSize);
          int tlblCentersDimension = MathUtils.round(ResultPoint.distance(topLeft, bottomLeft) / moduleSize);
          int dimension = ((tltrCentersDimension + tlblCentersDimension) / 2) + 7;
          switch (dimension & 0x03) { // mod 4
              case 0:
                  dimension++;
                  break;
              // 1? do nothing
              case 2:
                  dimension--;
                  break;
              case 3:
                  throw NotFoundException.getNotFoundInstance();
          }
          return dimension;
      }
  
      /**
       * <p>Computes an average estimated module size based on estimated derived from the positions
       * of the three finder patterns.</p>
       *
       * @param topLeft    detected top-left finder pattern center
       * @param topRight   detected top-right finder pattern center
       * @param bottomLeft detected bottom-left finder pattern center
       * @return estimated module size
       */
      protected final float calculateModuleSize(ResultPoint topLeft,
                                                ResultPoint topRight,
                                                ResultPoint bottomLeft) {
          // Take the average
          return (calculateModuleSizeOneWay(topLeft, topRight) +
                  calculateModuleSizeOneWay(topLeft, bottomLeft)) / 2.0f;
      }
  
      /**
       * <p>Estimates module size based on two finder patterns -- it uses
       * {@link #sizeOfBlackWhiteBlackRunBothWays(int, int, int, int)} to figure the
       * width of each, measuring along the axis between their centers.</p>
       */
      private float calculateModuleSizeOneWay(ResultPoint pattern, ResultPoint otherPattern) {
          float moduleSizeEst1 = sizeOfBlackWhiteBlackRunBothWays((int) pattern.getX(),
                  (int) pattern.getY(),
                  (int) otherPattern.getX(),
                  (int) otherPattern.getY());
          float moduleSizeEst2 = sizeOfBlackWhiteBlackRunBothWays((int) otherPattern.getX(),
                  (int) otherPattern.getY(),
                  (int) pattern.getX(),
                  (int) pattern.getY());
          if (Float.isNaN(moduleSizeEst1)) {
              return moduleSizeEst2 / 7.0f;
          }
          if (Float.isNaN(moduleSizeEst2)) {
              return moduleSizeEst1 / 7.0f;
          }
          // Average them, and divide by 7 since we've counted the width of 3 black modules,
          // and 1 white and 1 black module on either side. Ergo, divide sum by 14.
          return (moduleSizeEst1 + moduleSizeEst2) / 14.0f;
      }
  
      /**
       * See {@link #sizeOfBlackWhiteBlackRun(int, int, int, int)}; computes the total width of
       * a finder pattern by looking for a black-white-black run from the center in the direction
       * of another point (another finder pattern center), and in the opposite direction too.
       */
      private float sizeOfBlackWhiteBlackRunBothWays(int fromX, int fromY, int toX, int toY) {
  
          float result = sizeOfBlackWhiteBlackRun(fromX, fromY, toX, toY);
  
          // Now count other way -- don't run off image though of course
          float scale = 1.0f;
          int otherToX = fromX - (toX - fromX);
          if (otherToX < 0) {
              scale = fromX / (float) (fromX - otherToX);
              otherToX = 0;
          } else if (otherToX >= image.getWidth()) {
              scale = (image.getWidth() - 1 - fromX) / (float) (otherToX - fromX);
              otherToX = image.getWidth() - 1;
          }
          int otherToY = (int) (fromY - (toY - fromY) * scale);
  
          scale = 1.0f;
          if (otherToY < 0) {
              scale = fromY / (float) (fromY - otherToY);
              otherToY = 0;
          } else if (otherToY >= image.getHeight()) {
              scale = (image.getHeight() - 1 - fromY) / (float) (otherToY - fromY);
              otherToY = image.getHeight() - 1;
          }
          otherToX = (int) (fromX + (otherToX - fromX) * scale);
  
          result += sizeOfBlackWhiteBlackRun(fromX, fromY, otherToX, otherToY);
  
          // Middle pixel is double-counted this way; subtract 1
          return result - 1.0f;
      }
  
      /**
       * <p>This method traces a line from a point in the image, in the direction towards another point.
       * It begins in a black region, and keeps going until it finds white, then black, then white again.
       * It reports the distance from the start to this point.</p>
       *
       * <p>This is used when figuring out how wide a finder pattern is, when the finder pattern
       * may be skewed or rotated.</p>
       */
      private float sizeOfBlackWhiteBlackRun(int fromX, int fromY, int toX, int toY) {
          // Mild variant of Bresenham's algorithm;
          // see http://en.wikipedia.org/wiki/Bresenham's_line_algorithm
          boolean steep = Math.abs(toY - fromY) > Math.abs(toX - fromX);
          if (steep) {
              int temp = fromX;
              fromX = fromY;
              fromY = temp;
              temp = toX;
              toX = toY;
              toY = temp;
          }
  
          int dx = Math.abs(toX - fromX);
          int dy = Math.abs(toY - fromY);
          int error = -dx / 2;
          int xstep = fromX < toX ? 1 : -1;
          int ystep = fromY < toY ? 1 : -1;
  
          // In black pixels, looking for white, first or second time.
          int state = 0;
          // Loop up until x == toX, but not beyond
          int xLimit = toX + xstep;
          for (int x = fromX, y = fromY; x != xLimit; x += xstep) {
              int realX = steep ? y : x;
              int realY = steep ? x : y;
  
              // Does current pixel mean we have moved white to black or vice versa?
              // Scanning black in state 0,2 and white in state 1, so if we find the wrong
              // color, advance to next state or end if we are in state 2 already
              if ((state == 1) == image.get(realX, realY)) {
                  if (state == 2) {
                      return MathUtils.distance(x, y, fromX, fromY);
                  }
                  state++;
              }
  
              error += dy;
              if (error > 0) {
                  if (y == toY) {
                      break;
                  }
                  y += ystep;
                  error -= dx;
              }
          }
          // Found black-white-black; give the benefit of the doubt that the next pixel outside the image
          // is "white" so this last point at (toX+xStep,toY) is the right ending. This is really a
          // small approximation; (toX+xStep,toY+yStep) might be really correct. Ignore this.
          if (state == 2) {
              return MathUtils.distance(toX + xstep, toY, fromX, fromY);
          }
          // else we didn't find even black-white-black; no estimate is really possible
          return Float.NaN;
      }
  
      /**
       * <p>Attempts to locate an alignment pattern in a limited region of the image, which is
       * guessed to contain it. This method uses {@link AlignmentPattern}.</p>
       *
       * @param overallEstModuleSize estimated module size so far
       * @param estAlignmentX        x coordinate of center of area probably containing alignment pattern
       * @param estAlignmentY        y coordinate of above
       * @param allowanceFactor      number of pixels in all directions to search from the center
       * @return {@link AlignmentPattern} if found, or null otherwise
       * @throws NotFoundException if an unexpected error occurs during detection
       */
      protected final AlignmentPattern findAlignmentInRegion(float overallEstModuleSize,
                                                             int estAlignmentX,
                                                             int estAlignmentY,
                                                             float allowanceFactor)
              throws NotFoundException {
          // Look for an alignment pattern (3 modules in size) around where it
          // should be
          int allowance = (int) (allowanceFactor * overallEstModuleSize);
          int alignmentAreaLeftX = Math.max(0, estAlignmentX - allowance);
          int alignmentAreaRightX = Math.min(image.getWidth() - 1, estAlignmentX + allowance);
          if (alignmentAreaRightX - alignmentAreaLeftX < overallEstModuleSize * 3) {
              throw NotFoundException.getNotFoundInstance();
          }
  
          int alignmentAreaTopY = Math.max(0, estAlignmentY - allowance);
          int alignmentAreaBottomY = Math.min(image.getHeight() - 1, estAlignmentY + allowance);
          if (alignmentAreaBottomY - alignmentAreaTopY < overallEstModuleSize * 3) {
              throw NotFoundException.getNotFoundInstance();
          }
  
          AlignmentPatternFinder alignmentFinder =
                  new AlignmentPatternFinder(
                          image,
                          alignmentAreaLeftX,
                          alignmentAreaTopY,
                          alignmentAreaRightX - alignmentAreaLeftX,
                          alignmentAreaBottomY - alignmentAreaTopY,
                          overallEstModuleSize,
                          resultPointCallback);
          return alignmentFinder.find();
      }
  
  }
  