X-Git-Url: http://git.rot13.org/?a=blobdiff_plain;f=cpp%2Fcore%2Fsrc%2Fzxing%2Fqrcode%2Fdetector%2FFinderPatternFinder.cpp;fp=cpp%2Fcore%2Fsrc%2Fzxing%2Fqrcode%2Fdetector%2FFinderPatternFinder.cpp;h=af6609d9c32ee2e1344bf47433e66cd004226e86;hb=1bd3f8056f89c3e7c5163326ce2145de97acb829;hp=0000000000000000000000000000000000000000;hpb=b04d9b9e532b4c593f5b2a702d7904575f539468;p=zxing.git

diff --git a/cpp/core/src/zxing/qrcode/detector/FinderPatternFinder.cpp b/cpp/core/src/zxing/qrcode/detector/FinderPatternFinder.cpp
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+/*
+ *  FinderPatternFinder.cpp
+ *  zxing
+ *
+ *  Created by Christian Brunschen on 13/05/2008.
+ *  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/FinderPatternFinder.h>
+#include <zxing/ReaderException.h>
+#include <vector>
+#include <cmath>
+
+namespace zxing {
+namespace qrcode {
+
+using namespace std;
+
+class ClosestToAverageComparator {
+private:
+  float averageModuleSize_;
+public:
+  ClosestToAverageComparator(float averageModuleSize) :
+      averageModuleSize_(averageModuleSize) {
+  }
+  int operator()(Ref<FinderPattern> a, Ref<FinderPattern> b) {
+    float dA = abs(a->getEstimatedModuleSize() - averageModuleSize_);
+    float dB = abs(b->getEstimatedModuleSize() - averageModuleSize_);
+    return dA < dB ? -1 : dA > dB ? 1 : 0;
+  }
+};
+
+class CenterComparator {
+public:
+  int operator()(Ref<FinderPattern> a, Ref<FinderPattern> b) {
+    return b->getCount() - a->getCount();
+  }
+};
+
+int FinderPatternFinder::CENTER_QUORUM = 2;
+int FinderPatternFinder::MIN_SKIP = 3;
+int FinderPatternFinder::MAX_MODULES = 57;
+
+float FinderPatternFinder::centerFromEnd(int* stateCount, int end) {
+  return (float)(end - stateCount[4] - stateCount[3]) - stateCount[2] / 2.0f;
+}
+
+bool FinderPatternFinder::foundPatternCross(int* stateCount) {
+  int totalModuleSize = 0;
+  for (int i = 0; i < 5; i++) {
+    if (stateCount[i] == 0) {
+      return false;
+    }
+    totalModuleSize += stateCount[i];
+  }
+  if (totalModuleSize < 7) {
+    return false;
+  }
+  float moduleSize = (float)totalModuleSize / 7.0f;
+  float maxVariance = moduleSize / 2.0f;
+  // Allow less than 50% variance from 1-1-3-1-1 proportions
+  return abs(moduleSize - stateCount[0]) < maxVariance && abs(moduleSize - stateCount[1]) < maxVariance && abs(3.0f
+         * moduleSize - stateCount[2]) < 3.0f * maxVariance && abs(moduleSize - stateCount[3]) < maxVariance && abs(
+           moduleSize - stateCount[4]) < maxVariance;
+}
+
+float FinderPatternFinder::crossCheckVertical(size_t startI, size_t centerJ, int maxCount, int originalStateCountTotal) {
+
+  int maxI = image_->getHeight();
+  int stateCount[5];
+  for (int i = 0; i < 5; i++)
+    stateCount[i] = 0;
+
+
+  // Start counting up from center
+  int i = startI;
+  while (i >= 0 && image_->get(centerJ, i)) {
+    stateCount[2]++;
+    i--;
+  }
+  if (i < 0) {
+    return 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 NAN;
+  }
+  while (i >= 0 && image_->get(centerJ, i) && stateCount[0] <= maxCount) {
+    stateCount[0]++;
+    i--;
+  }
+  if (stateCount[0] > maxCount) {
+    return NAN;
+  }
+
+  // Now also count down from center
+  i = startI + 1;
+  while (i < maxI && image_->get(centerJ, i)) {
+    stateCount[2]++;
+    i++;
+  }
+  if (i == maxI) {
+    return NAN;
+  }
+  while (i < maxI && !image_->get(centerJ, i) && stateCount[3] < maxCount) {
+    stateCount[3]++;
+    i++;
+  }
+  if (i == maxI || stateCount[3] >= maxCount) {
+    return NAN;
+  }
+  while (i < maxI && image_->get(centerJ, i) && stateCount[4] < maxCount) {
+    stateCount[4]++;
+    i++;
+  }
+  if (stateCount[4] >= maxCount) {
+    return NAN;
+  }
+
+  // If we found a finder-pattern-like section, but its size is more than 20% different than
+  // the original, assume it's a false positive
+  int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];
+  if (5 * abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {
+    return NAN;
+  }
+
+  return foundPatternCross(stateCount) ? centerFromEnd(stateCount, i) : NAN;
+}
+
+float FinderPatternFinder::crossCheckHorizontal(size_t startJ, size_t centerI, int maxCount,
+    int originalStateCountTotal) {
+
+  int maxJ = image_->getWidth();
+  int stateCount[5];
+  for (int i = 0; i < 5; i++)
+    stateCount[i] = 0;
+
+  int j = startJ;
+  while (j >= 0 && image_->get(j, centerI)) {
+    stateCount[2]++;
+    j--;
+  }
+  if (j < 0) {
+    return NAN;
+  }
+  while (j >= 0 && !image_->get(j, centerI) && stateCount[1] <= maxCount) {
+    stateCount[1]++;
+    j--;
+  }
+  if (j < 0 || stateCount[1] > maxCount) {
+    return NAN;
+  }
+  while (j >= 0 && image_->get(j, centerI) && stateCount[0] <= maxCount) {
+    stateCount[0]++;
+    j--;
+  }
+  if (stateCount[0] > maxCount) {
+    return NAN;
+  }
+
+  j = startJ + 1;
+  while (j < maxJ && image_->get(j, centerI)) {
+    stateCount[2]++;
+    j++;
+  }
+  if (j == maxJ) {
+    return NAN;
+  }
+  while (j < maxJ && !image_->get(j, centerI) && stateCount[3] < maxCount) {
+    stateCount[3]++;
+    j++;
+  }
+  if (j == maxJ || stateCount[3] >= maxCount) {
+    return NAN;
+  }
+  while (j < maxJ && image_->get(j, centerI) && stateCount[4] < maxCount) {
+    stateCount[4]++;
+    j++;
+  }
+  if (stateCount[4] >= maxCount) {
+    return 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 * abs(stateCountTotal - originalStateCountTotal) >= originalStateCountTotal) {
+    return NAN;
+  }
+
+  return foundPatternCross(stateCount) ? centerFromEnd(stateCount, j) : NAN;
+}
+
+bool FinderPatternFinder::handlePossibleCenter(int* stateCount, size_t i, size_t j) {
+  int stateCountTotal = stateCount[0] + stateCount[1] + stateCount[2] + stateCount[3] + stateCount[4];
+  float centerJ = centerFromEnd(stateCount, j);
+  float centerI = crossCheckVertical(i, (size_t)centerJ, stateCount[2], stateCountTotal);
+  if (!isnan(centerI)) {
+    // Re-cross check
+    centerJ = crossCheckHorizontal((size_t)centerJ, (size_t)centerI, stateCount[2], stateCountTotal);
+    if (!isnan(centerJ)) {
+      float estimatedModuleSize = (float)stateCountTotal / 7.0f;
+      bool found = false;
+      size_t max = possibleCenters_.size();
+      for (size_t index = 0; index < max; index++) {
+        Ref<FinderPattern> center = possibleCenters_[index];
+        // Look for about the same center and module size:
+        if (center->aboutEquals(estimatedModuleSize, centerI, centerJ)) {
+          center->incrementCount();
+          found = true;
+          break;
+        }
+      }
+      if (!found) {
+        Ref<FinderPattern> newPattern(new FinderPattern(centerJ, centerI, estimatedModuleSize));
+        possibleCenters_.push_back(newPattern);
+      }
+      return true;
+    }
+  }
+  return false;
+}
+
+int FinderPatternFinder::findRowSkip() {
+  size_t max = possibleCenters_.size();
+  if (max <= 1) {
+    return 0;
+  }
+  Ref<FinderPattern> firstConfirmedCenter;
+  for (size_t i = 0; i < max; i++) {
+    Ref<FinderPattern> center = possibleCenters_[i];
+    if (center->getCount() >= CENTER_QUORUM) {
+      if (firstConfirmedCenter == 0) {
+        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 first. Draw it out.
+        hasSkipped_ = true;
+        return (int)(abs(firstConfirmedCenter->getX() - center->getX()) - abs(firstConfirmedCenter->getY()
+                     - center->getY()));
+      }
+    }
+  }
+  return 0;
+}
+
+bool FinderPatternFinder::haveMultiplyConfirmedCenters() {
+  int confirmedCount = 0;
+  float totalModuleSize = 0.0f;
+  size_t max = possibleCenters_.size();
+  for (size_t i = 0; i < max; i++) {
+    Ref<FinderPattern> pattern = possibleCenters_[i];
+    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
+  // 15% of the total module size estimates, it's too much.
+  float average = totalModuleSize / max;
+  float totalDeviation = 0.0f;
+  for (size_t i = 0; i < max; i++) {
+    Ref<FinderPattern> pattern = possibleCenters_[i];
+    totalDeviation += abs(pattern->getEstimatedModuleSize() - average);
+  }
+  return totalDeviation <= 0.15f * totalModuleSize;
+}
+
+vector<Ref<FinderPattern> > FinderPatternFinder::selectBestPatterns() {
+  sort(possibleCenters_.begin(), possibleCenters_.end(), CenterComparator());
+  size_t size = 0;
+  size_t max = possibleCenters_.size();
+  while (size < max) {
+    if (possibleCenters_[size]->getCount() < CENTER_QUORUM) {
+      break;
+    }
+    size++;
+  }
+
+  if (size < 3) {
+    // Couldn't find enough finder patterns
+    throw zxing::ReaderException("Could not find three finder patterns");
+  }
+
+  if (size == 3) {
+    // Found just enough -- hope these are good!
+    vector<Ref<FinderPattern> > result(3);
+    result[0] = possibleCenters_[0];
+    result[1] = possibleCenters_[1];
+    result[2] = possibleCenters_[2];
+    return result;
+  }
+
+  // Hmm, multiple found. We need to pick the best three. Find the most
+  // popular ones whose module size is nearest the average
+  // This does not work for multiple qr codes in the same image
+  float averageModuleSize = 0.0f;
+  for (size_t i = 0; i < size; i++) {
+    averageModuleSize += possibleCenters_[i]->getEstimatedModuleSize();
+  }
+  averageModuleSize /= (float)size;
+
+  sort(possibleCenters_.begin(), possibleCenters_.end(), ClosestToAverageComparator(averageModuleSize));
+
+  vector<Ref<FinderPattern> > result(3);
+  result[0] = possibleCenters_[0];
+  result[1] = possibleCenters_[1];
+  result[2] = possibleCenters_[2];
+  return result;
+}
+
+vector<Ref<FinderPattern> > FinderPatternFinder::orderBestPatterns(vector<Ref<FinderPattern> > patterns) {
+  // Find distances between pattern centers
+  float abDistance = distance(patterns[0], patterns[1]);
+  float bcDistance = distance(patterns[1], patterns[2]);
+  float acDistance = distance(patterns[0], patterns[2]);
+
+  Ref<FinderPattern> topLeft;
+  Ref<FinderPattern> topRight;
+  Ref<FinderPattern> bottomLeft;
+  // Assume one closest to other two is top left;
+  // topRight and bottomLeft will just be guesses below at first
+  if (bcDistance >= abDistance && bcDistance >= acDistance) {
+    topLeft = patterns[0];
+    topRight = patterns[1];
+    bottomLeft = patterns[2];
+  } else if (acDistance >= bcDistance && acDistance >= abDistance) {
+    topLeft = patterns[1];
+    topRight = patterns[0];
+    bottomLeft = patterns[2];
+  } else {
+    topLeft = patterns[2];
+    topRight = patterns[0];
+    bottomLeft = patterns[1];
+  }
+
+  // Use cross product to figure out which of other1/2 is the bottom left
+  // pattern. The vector "top-left -> bottom-left" x "top-left -> top-right"
+  // should yield a vector with positive z component
+  if ((bottomLeft->getY() - topLeft->getY()) * (topRight->getX() - topLeft->getX()) < (bottomLeft->getX()
+      - topLeft->getX()) * (topRight->getY() - topLeft->getY())) {
+    Ref<FinderPattern> temp = topRight;
+    topRight = bottomLeft;
+    bottomLeft = temp;
+  }
+
+  vector<Ref<FinderPattern> > results(3);
+  results[0] = bottomLeft;
+  results[1] = topLeft;
+  results[2] = topRight;
+  return results;
+}
+
+float FinderPatternFinder::distance(Ref<ResultPoint> p1, Ref<ResultPoint> p2) {
+  float dx = p1->getX() - p2->getX();
+  float dy = p1->getY() - p2->getY();
+  return (float)sqrt(dx * dx + dy * dy);
+}
+
+FinderPatternFinder::FinderPatternFinder(Ref<BitMatrix> image) :
+    image_(image), possibleCenters_(), hasSkipped_(false) {
+}
+
+Ref<FinderPatternInfo> FinderPatternFinder::find() {
+  size_t maxI = image_->getHeight();
+  size_t 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
+
+  // As this is used often, we use an integer array instead of valarray
+  int stateCount[5];
+  bool done = false;
+
+
+  // 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.
+  size_t iSkip = MIN_SKIP;
+
+  // This is slightly faster than using the Ref. Efficiency is important here
+  BitMatrix& matrix = *image_;
+
+  for (size_t i = iSkip - 1; i < maxI && !done; i += iSkip) {
+    // Get a row of black/white values
+
+    stateCount[0] = 0;
+    stateCount[1] = 0;
+    stateCount[2] = 0;
+    stateCount[3] = 0;
+    stateCount[4] = 0;
+    int currentState = 0;
+    for (size_t j = 0; j < maxJ; j++) {
+      if (matrix.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
+              bool confirmed = handlePossibleCenter(stateCount, i, j);
+              if (confirmed) {
+                iSkip = 1; // Go back to examining each line
+                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 {
+                // Advance to next black pixel
+                do {
+                  j++;
+                } while (j < maxJ && !image_->get(j, i));
+                j--; // back up to that last white pixel
+              }
+              // Clear state to start looking again
+              currentState = 0;
+              stateCount[0] = 0;
+              stateCount[1] = 0;
+              stateCount[2] = 0;
+              stateCount[3] = 0;
+              stateCount[4] = 0;
+            } else { // No, shift counts back by two
+              stateCount[0] = stateCount[2];
+              stateCount[1] = stateCount[3];
+              stateCount[2] = stateCount[4];
+              stateCount[3] = 1;
+              stateCount[4] = 0;
+              currentState = 3;
+            }
+          } else {
+            stateCount[++currentState]++;
+          }
+        } else { // Counting white pixels
+          stateCount[currentState]++;
+        }
+      }
+    }
+    if (foundPatternCross(stateCount)) {
+      bool confirmed = handlePossibleCenter(stateCount, i, maxJ);
+      if (confirmed) {
+        iSkip = stateCount[0];
+        if (hasSkipped_) {
+          // Found a third one
+          done = haveMultiplyConfirmedCenters();
+        }
+      }
+    }
+  }
+
+  vector<Ref<FinderPattern> > patternInfo = selectBestPatterns();
+  patternInfo = orderBestPatterns(patternInfo);
+
+  Ref<FinderPatternInfo> result(new FinderPatternInfo(patternInfo));
+  return result;
+}
+}
+}