text: /*
   *  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 <cmath>
  #include <sstream>
  #include <cstdlib>
  
  namespace zxing {
  namespace qrcode {
  
  using namespace std;
  
  Detector::Detector(Ref<BitMatrix> image) :
      image_(image) {
  }
  
  Ref<BitMatrix> Detector::getImage() {
     return image_;
  }
  
  Ref<DetectorResult> Detector::detect(DecodeHints const& hints) {
    callback_ = hints.getResultPointCallback();
    FinderPatternFinder finder(image_, hints.getResultPointCallback());
    Ref<FinderPatternInfo> info(finder.find(hints));
  
    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& 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));
    std::vector<Ref<ResultPoint> > points(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, transform));
    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 = sourceBottomRightY = dimMinusThree - 3.0f;
    } 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 = 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 = int(FinderPatternFinder::distance(topLeft, topRight) / moduleSize + 0.5f);
    int tlblCentersDimension = int(FinderPatternFinder::distance(topLeft, bottomLeft) / moduleSize + 0.5f);
    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 (isnan(moduleSizeEst1)) {
      return moduleSizeEst2;
    }
    if (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) {
            int diffX = x - fromX;
            int diffY = y - fromY;
            return (float) sqrt((double) (diffX * diffX + diffY * diffY));
          }
          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) {
        int diffX = toX + xstep - fromX;
        int diffY = toY - fromY;
        return (float) sqrt((double) (diffX * diffX + diffY * diffY));
      }
      // 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();
  }
  
  }
  }
  