MonochromeRectangleDetector.cpp Example File

 // -*- mode:c++; tab-width:2; indent-tabs-mode:nil; c-basic-offset:2 -*-
 /*
  *  MonochromeRectangleDetector.cpp
  *  y_wmk
  *
  *  Created by Luiz Silva on 09/02/2010.
  *  Copyright 2010 y_wmk 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/NotFoundException.h>
 #include <zxing/common/detector/MonochromeRectangleDetector.h>
 #include <sstream>
 #include <algorithm>

 using std::vector;
 using zxing::Ref;
 using zxing::ResultPoint;
 using zxing::TwoInts;
 using zxing::MonochromeRectangleDetector;

 vector<Ref<ResultPoint> > MonochromeRectangleDetector::detect() {
   int height = image_->getHeight();
   int width = image_->getWidth();
   int halfHeight = height >> 1;
   int halfWidth = width >> 1;
   int deltaY = std::max(1, height / (MAX_MODULES << 3));
   int deltaX = std::max(1, width / (MAX_MODULES << 3));

   int top = 0;
   int bottom = height;
   int left = 0;
   int right = width;
   Ref<ResultPoint> pointA(findCornerFromCenter(halfWidth, 0, left, right,
                                                halfHeight, -deltaY, top, bottom, halfWidth >> 1));
   top = (int) pointA->getY() - 1;;
   Ref<ResultPoint> pointB(findCornerFromCenter(halfWidth, -deltaX, left, right,
                                                halfHeight, 0, top, bottom, halfHeight >> 1));
   left = (int) pointB->getX() - 1;
   Ref<ResultPoint> pointC(findCornerFromCenter(halfWidth, deltaX, left, right,
                                                halfHeight, 0, top, bottom, halfHeight >> 1));
   right = (int) pointC->getX() + 1;
   Ref<ResultPoint> pointD(findCornerFromCenter(halfWidth, 0, left, right,
                                                halfHeight, deltaY, top, bottom, halfWidth >> 1));
   bottom = (int) pointD->getY() + 1;

   // Go try to find point A again with better information -- might have been off at first.
   pointA.reset(findCornerFromCenter(halfWidth, 0, left, right,
                                     halfHeight, -deltaY, top, bottom, halfWidth >> 2));

   vector<Ref<ResultPoint> > corners(4);
   corners[0].reset(pointA);
   corners[1].reset(pointB);
   corners[2].reset(pointC);
   corners[3].reset(pointD);
   return corners;
 }

 Ref<ResultPoint> MonochromeRectangleDetector::findCornerFromCenter(int centerX, int deltaX, int left, int right,
                                                                    int centerY, int deltaY, int top, int bottom, int maxWhiteRun) {
   Ref<TwoInts> lastRange(NULL);
   for (int y = centerY, x = centerX;
        y < bottom && y >= top && x < right && x >= left;
        y += deltaY, x += deltaX) {
     Ref<TwoInts> range(NULL);
     if (deltaX == 0) {
       // horizontal slices, up and down
       range = blackWhiteRange(y, maxWhiteRun, left, right, true);
     } else {
       // vertical slices, left and right
       range = blackWhiteRange(x, maxWhiteRun, top, bottom, false);
     }
     if (range == NULL) {
       if (lastRange == NULL) {
         throw NotFoundException("Couldn't find corners (lastRange = NULL) ");
       } else {
         // lastRange was found
         if (deltaX == 0) {
           int lastY = y - deltaY;
           if (lastRange->start < centerX) {
             if (lastRange->end > centerX) {
               // straddle, choose one or the other based on direction
               Ref<ResultPoint> result(new ResultPoint(deltaY > 0 ? lastRange->start : lastRange->end, lastY));
               return result;
             }
             Ref<ResultPoint> result(new ResultPoint(lastRange->start, lastY));
             return result;
           } else {
             Ref<ResultPoint> result(new ResultPoint(lastRange->end, lastY));
             return result;
           }
         } else {
           int lastX = x - deltaX;
           if (lastRange->start < centerY) {
             if (lastRange->end > centerY) {
               Ref<ResultPoint> result(new ResultPoint(lastX, deltaX < 0 ? lastRange->start : lastRange->end));
               return result;
             }
             Ref<ResultPoint> result(new ResultPoint(lastX, lastRange->start));
             return result;
           } else {
             Ref<ResultPoint> result(new ResultPoint(lastX, lastRange->end));
             return result;
           }
         }
       }
     }
     lastRange = range;
   }
   throw NotFoundException("Couldn't find corners");
 }

 Ref<TwoInts> MonochromeRectangleDetector::blackWhiteRange(int fixedDimension, int maxWhiteRun, int minDim, int maxDim,
                                                           bool horizontal) {

   int center = (minDim + maxDim) >> 1;

   // Scan left/up first
   int start = center;
   while (start >= minDim) {
     if (horizontal ? image_->get(start, fixedDimension) : image_->get(fixedDimension, start)) {
       start--;
     } else {
       int whiteRunStart = start;
       do {
         start--;
       } while (start >= minDim && !(horizontal ? image_->get(start, fixedDimension) :
                                     image_->get(fixedDimension, start)));
       int whiteRunSize = whiteRunStart - start;
       if (start < minDim || whiteRunSize > maxWhiteRun) {
         start = whiteRunStart;
         break;
       }
     }
   }
   start++;

   // Then try right/down
   int end = center;
   while (end < maxDim) {
     if (horizontal ? image_->get(end, fixedDimension) : image_->get(fixedDimension, end)) {
       end++;
     } else {
       int whiteRunStart = end;
       do {
         end++;
       } while (end < maxDim && !(horizontal ? image_->get(end, fixedDimension) :
                                  image_->get(fixedDimension, end)));
       int whiteRunSize = end - whiteRunStart;
       if (end >= maxDim || whiteRunSize > maxWhiteRun) {
         end = whiteRunStart;
         break;
       }
     }
   }
   end--;
   Ref<TwoInts> result(NULL);
   if (end > start) {
     result = new TwoInts;
     result->start = start;
     result->end = end;
   }
   return result;
 }