Examples with FinderPatternInfo com.google.zxing.qrcode.detector.FinderPatternInfo used on opensource projects

Example 6 with FinderPatternInfo

use of com.google.zxing.qrcode.detector.FinderPatternInfo in project weex-example by KalicyZhou.

the class MultiFinderPatternFinder method selectMutipleBestPatterns.

/**
   * @return the 3 best {@link FinderPattern}s from our list of candidates. The "best" are
   *         those that have been detected at least {@link #CENTER_QUORUM} times, and whose module
   *         size differs from the average among those patterns the least
   * @throws NotFoundException if 3 such finder patterns do not exist
   */
private FinderPattern[][] selectMutipleBestPatterns() throws NotFoundException {
    List<FinderPattern> possibleCenters = getPossibleCenters();
    int size = possibleCenters.size();
    if (size < 3) {
        // Couldn't find enough finder patterns
        throw NotFoundException.getNotFoundInstance();
    }
    /*
     * Begin HE modifications to safely detect multiple codes of equal size
     */
    if (size == 3) {
        return new FinderPattern[][] { new FinderPattern[] { possibleCenters.get(0), possibleCenters.get(1), possibleCenters.get(2) } };
    }
    // Sort by estimated module size to speed up the upcoming checks
    Collections.sort(possibleCenters, new ModuleSizeComparator());
    /*
     * Now lets start: build a list of tuples of three finder locations that
     *  - feature similar module sizes
     *  - are placed in a distance so the estimated module count is within the QR specification
     *  - have similar distance between upper left/right and left top/bottom finder patterns
     *  - form a triangle with 90° angle (checked by comparing top right/bottom left distance
     *    with pythagoras)
     *
     * Note: we allow each point to be used for more than one code region: this might seem
     * counterintuitive at first, but the performance penalty is not that big. At this point,
     * we cannot make a good quality decision whether the three finders actually represent
     * a QR code, or are just by chance layouted so it looks like there might be a QR code there.
     * So, if the layout seems right, lets have the decoder try to decode.     
     */
    // holder for the results
    List<FinderPattern[]> results = new ArrayList<>();
    for (int i1 = 0; i1 < (size - 2); i1++) {
        FinderPattern p1 = possibleCenters.get(i1);
        if (p1 == null) {
            continue;
        }
        for (int i2 = i1 + 1; i2 < (size - 1); i2++) {
            FinderPattern p2 = possibleCenters.get(i2);
            if (p2 == null) {
                continue;
            }
            // Compare the expected module sizes; if they are really off, skip
            float vModSize12 = (p1.getEstimatedModuleSize() - p2.getEstimatedModuleSize()) / Math.min(p1.getEstimatedModuleSize(), p2.getEstimatedModuleSize());
            float vModSize12A = Math.abs(p1.getEstimatedModuleSize() - p2.getEstimatedModuleSize());
            if (vModSize12A > DIFF_MODSIZE_CUTOFF && vModSize12 >= DIFF_MODSIZE_CUTOFF_PERCENT) {
                // any more interesting elements for the given p1.
                break;
            }
            for (int i3 = i2 + 1; i3 < size; i3++) {
                FinderPattern p3 = possibleCenters.get(i3);
                if (p3 == null) {
                    continue;
                }
                // Compare the expected module sizes; if they are really off, skip
                float vModSize23 = (p2.getEstimatedModuleSize() - p3.getEstimatedModuleSize()) / Math.min(p2.getEstimatedModuleSize(), p3.getEstimatedModuleSize());
                float vModSize23A = Math.abs(p2.getEstimatedModuleSize() - p3.getEstimatedModuleSize());
                if (vModSize23A > DIFF_MODSIZE_CUTOFF && vModSize23 >= DIFF_MODSIZE_CUTOFF_PERCENT) {
                    // any more interesting elements for the given p1.
                    break;
                }
                FinderPattern[] test = { p1, p2, p3 };
                ResultPoint.orderBestPatterns(test);
                // Calculate the distances: a = topleft-bottomleft, b=topleft-topright, c = diagonal
                FinderPatternInfo info = new FinderPatternInfo(test);
                float dA = ResultPoint.distance(info.getTopLeft(), info.getBottomLeft());
                float dC = ResultPoint.distance(info.getTopRight(), info.getBottomLeft());
                float dB = ResultPoint.distance(info.getTopLeft(), info.getTopRight());
                // Check the sizes
                float estimatedModuleCount = (dA + dB) / (p1.getEstimatedModuleSize() * 2.0f);
                if (estimatedModuleCount > MAX_MODULE_COUNT_PER_EDGE || estimatedModuleCount < MIN_MODULE_COUNT_PER_EDGE) {
                    continue;
                }
                // Calculate the difference of the edge lengths in percent
                float vABBC = Math.abs((dA - dB) / Math.min(dA, dB));
                if (vABBC >= 0.1f) {
                    continue;
                }
                // Calculate the diagonal length by assuming a 90° angle at topleft
                float dCpy = (float) Math.sqrt(dA * dA + dB * dB);
                // Compare to the real distance in %
                float vPyC = Math.abs((dC - dCpy) / Math.min(dC, dCpy));
                if (vPyC >= 0.1f) {
                    continue;
                }
                // All tests passed!
                results.add(test);
            }
        // end iterate p3
        }
    // end iterate p2
    }
    if (!results.isEmpty()) {
        return results.toArray(new FinderPattern[results.size()][]);
    }
    // Nothing found!
    throw NotFoundException.getNotFoundInstance();
}