text: // -*- mode:c++; tab-width:2; indent-tabs-mode:nil; c-basic-offset:2 -*-
  /*
   *  Detector.cpp
   *  zxing
   *
   *  Created by Christian Brunschen on 14/05/2008.
   *  Copyright 2008 ZXing authors All rights reserved.
   *
   * 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.
   */
  
  #include <zxing/qrcode/detector/Detector.h>
  #include <zxing/qrcode/detector/FinderPatternFinder.h>
  #include <zxing/qrcode/detector/FinderPattern.h>
  #include <zxing/qrcode/detector/AlignmentPattern.h>
  #include <zxing/qrcode/detector/AlignmentPatternFinder.h>
  #include <zxing/qrcode/Version.h>
  #include <zxing/common/GridSampler.h>
  #include <zxing/DecodeHints.h>
  #include <zxing/common/detector/MathUtils.h>
  #include <sstream>
  #include <cstdlib>
  #include <algorithm>  // vs12, std::min und std:max
  
  using std::ostringstream;
  using std::abs;
  using std::min;
  using std::max;
  using zxing::qrcode::Detector;
  using zxing::Ref;
  using zxing::BitMatrix;
  using zxing::ResultPointCallback;
  using zxing::DetectorResult;
  using zxing::PerspectiveTransform;
  using zxing::qrcode::AlignmentPattern;
  using zxing::common::detector::MathUtils;
  
  // VC++
  using zxing::DecodeHints;
  using zxing::qrcode::FinderPatternFinder;
  using zxing::qrcode::FinderPatternInfo;
  using zxing::ResultPoint;
  
  Detector::Detector(Ref<BitMatrix> image) :
    image_(image) {
  }
  
  Ref<BitMatrix> Detector::getImage() const {
    return image_;
  }
  
  Ref<ResultPointCallback> Detector::getResultPointCallback() const {
    return callback_;
  }
  
  Ref<DetectorResult> Detector::detect(DecodeHints const& hints) {
    callback_ = hints.getResultPointCallback();
    FinderPatternFinder finder(image_, hints.getResultPointCallback());
    Ref<FinderPatternInfo> info(finder.find(hints));
    return processFinderPatternInfo(info);
  }
  
  Ref<DetectorResult> Detector::processFinderPatternInfo(Ref<FinderPatternInfo> info){
    Ref<FinderPattern> topLeft(info->getTopLeft());
    Ref<FinderPattern> topRight(info->getTopRight());
    Ref<FinderPattern> bottomLeft(info->getBottomLeft());
  
    float moduleSize = calculateModuleSize(topLeft, topRight, bottomLeft);
    if (moduleSize < 1.0f) {
      throw zxing::ReaderException("bad module size");
    }
    int dimension = computeDimension(topLeft, topRight, bottomLeft, moduleSize);
    Version *provisionalVersion = Version::getProvisionalVersionForDimension(dimension);
    int modulesBetweenFPCenters = provisionalVersion->getDimensionForVersion() - 7;
  
    Ref<AlignmentPattern> alignmentPattern;
    // Anything above version 1 has an alignment pattern
    if (provisionalVersion->getAlignmentPatternCenters().size() > 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 / (float)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, (float)i);
          break;
        } catch (zxing::ReaderException const& re) {
          (void)re;
          // try next round
        }
      }
      if (alignmentPattern == 0) {
        // Try anyway
      }
  
    }
  
    Ref<PerspectiveTransform> transform = createTransform(topLeft, topRight, bottomLeft, alignmentPattern, dimension);
    Ref<BitMatrix> bits(sampleGrid(image_, dimension, transform));
    ArrayRef< Ref<ResultPoint> > points(new Array< Ref<ResultPoint> >(alignmentPattern == 0 ? 3 : 4));
    points[0].reset(bottomLeft);
    points[1].reset(topLeft);
    points[2].reset(topRight);
    if (alignmentPattern != 0) {
      points[3].reset(alignmentPattern);
    }
  
    Ref<DetectorResult> result(new DetectorResult(bits, points));
    return result;
  }
  
  Ref<PerspectiveTransform> Detector::createTransform(Ref<ResultPoint> topLeft, Ref<ResultPoint> topRight, Ref <
                                                      ResultPoint > bottomLeft, Ref<ResultPoint> alignmentPattern, int dimension) {
  
    float dimMinusThree = (float)dimension - 3.5f;
    float bottomRightX;
    float bottomRightY;
    float sourceBottomRightX;
    float sourceBottomRightY;
    if (alignmentPattern != 0) {
      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;
    }
  
    Ref<PerspectiveTransform> transform(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()));
  
    return transform;
  }
  
  Ref<BitMatrix> Detector::sampleGrid(Ref<BitMatrix> image, int dimension, Ref<PerspectiveTransform> transform) {
    GridSampler &sampler = GridSampler::getInstance();
    return sampler.sampleGrid(image, dimension, transform);
  }
  
  int Detector::computeDimension(Ref<ResultPoint> topLeft, Ref<ResultPoint> topRight, Ref<ResultPoint> bottomLeft,
                                 float moduleSize) {
    int tltrCentersDimension =
      MathUtils::round(ResultPoint::distance(topLeft, topRight) / moduleSize);
    int tlblCentersDimension =
      MathUtils::round(ResultPoint::distance(topLeft, bottomLeft) / moduleSize);
    int dimension = ((tltrCentersDimension + tlblCentersDimension) >> 1) + 7;
    switch (dimension & 0x03) { // mod 4
    case 0:
      dimension++;
      break;
      // 1? do nothing
    case 2:
      dimension--;
      break;
    case 3:
      ostringstream s;
      s << "Bad dimension: " << dimension;
      throw zxing::ReaderException(s.str().c_str());
    }
    return dimension;
  }
  
  float Detector::calculateModuleSize(Ref<ResultPoint> topLeft, Ref<ResultPoint> topRight, Ref<ResultPoint> bottomLeft) {
    // Take the average
    return (calculateModuleSizeOneWay(topLeft, topRight) + calculateModuleSizeOneWay(topLeft, bottomLeft)) / 2.0f;
  }
  
  float Detector::calculateModuleSizeOneWay(Ref<ResultPoint> pattern, Ref<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 (zxing::isnan(moduleSizeEst1)) {
      return moduleSizeEst2;
    }
    if (zxing::isnan(moduleSizeEst2)) {
      return moduleSizeEst1;
    }
    // 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;
  }
  
  float Detector::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 = (float) fromX / (float) (fromX - otherToX);
      otherToX = 0;
    } else if (otherToX >= (int)image_->getWidth()) {
      scale = (float) (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 = (float) fromY / (float) (fromY - otherToY);
      otherToY = 0;
    } else if (otherToY >= (int)image_->getHeight()) {
      scale = (float) (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;
  }
  
  float Detector::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
    bool steep = abs(toY - fromY) > abs(toX - fromX);
    if (steep) {
      int temp = fromX;
      fromX = fromY;
      fromY = temp;
      temp = toX;
      toX = toY;
      toY = temp;
    }
  
    int dx = abs(toX - fromX);
    int dy = abs(toY - fromY);
    int error = -dx >> 1;
    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?
      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 nan();
  }
  
  Ref<AlignmentPattern> Detector::findAlignmentInRegion(float overallEstModuleSize, int estAlignmentX, int estAlignmentY,
                                                        float allowanceFactor) {
    // Look for an alignment pattern (3 modules in size) around where it
    // should be
    int allowance = (int)(allowanceFactor * overallEstModuleSize);
    int alignmentAreaLeftX = max(0, estAlignmentX - allowance);
    int alignmentAreaRightX = min((int)(image_->getWidth() - 1), estAlignmentX + allowance);
    if (alignmentAreaRightX - alignmentAreaLeftX < overallEstModuleSize * 3) {
      throw zxing::ReaderException("region too small to hold alignment pattern");
    }
    int alignmentAreaTopY = max(0, estAlignmentY - allowance);
    int alignmentAreaBottomY = min((int)(image_->getHeight() - 1), estAlignmentY + allowance);
    if (alignmentAreaBottomY - alignmentAreaTopY < overallEstModuleSize * 3) {
      throw zxing::ReaderException("region too small to hold alignment pattern");
    }
  
    AlignmentPatternFinder alignmentFinder(image_, alignmentAreaLeftX, alignmentAreaTopY, alignmentAreaRightX
                                           - alignmentAreaLeftX, alignmentAreaBottomY - alignmentAreaTopY, overallEstModuleSize, callback_);
    return alignmentFinder.find();
  }
  