opencv CalcHist2D_8uInvoker

opencv  CalcHist2D_8uInvoker

class CalcHist2D_8uInvoker
{
public:
    CalcHist2D_8uInvoker( const std::vector<uchar*>& _ptrs, const std::vector<int>& _deltas,
                          Size imsize, Mat& hist, int dims, const std::vector<size_t>& _tab,
                          tbb::mutex* lock )
        : mask_(_ptrs[dims]),
          mstep_(_deltas[dims*2 + 1]),
          imageWidth_(imsize.width),
          histSize_(hist.size()), histType_(hist.type()),
          tab_((size_t*)&_tab[0]),
          histogramWriteLock_(lock),
          globalHistogram_(hist.data)
    {
        p_[0] = (uchar*)(&_ptrs[0])[0]; p_[1] = (uchar*)(&_ptrs[0])[1];
        step_[0] = (&_deltas[0])[1];    step_[1] = (&_deltas[0])[3];
        d_[0] = (&_deltas[0])[0];       d_[1] = (&_deltas[0])[2];
    }

    void operator()( const BlockedRange& range ) const
    {
        uchar* p0 = p_[0] + range.begin()*(step_[0] + imageWidth_*d_[0]);
        uchar* p1 = p_[1] + range.begin()*(step_[1] + imageWidth_*d_[1]);
        uchar* mask = mask_ + range.begin()*mstep_;

        Mat localHist = Mat::zeros(histSize_, histType_);
        uchar* localHistData = localHist.data;
        tbb::mutex::scoped_lock lock;

        for(int i = range.begin(); i < range.end(); i++, p0 += step_[0], p1 += step_[1])
        {
            if( !mask_ )
            {
                for( int x = 0; x < imageWidth_; x++, p0 += d_[0], p1 += d_[1] )
                {
                    size_t idx = tab_[*p0] + tab_[*p1 + 256];
                    if( idx < OUT_OF_RANGE )
                    {
                        ++*(int*)(localHistData + idx);
                    }
                }
            }
            else
            {
                for( int x = 0; x < imageWidth_; x++, p0 += d_[0], p1 += d_[1] )
                {
                    size_t idx;
                    if( mask[x] && (idx = tab_[*p0] + tab_[*p1 + 256]) < OUT_OF_RANGE )
                    {
                        ++*(int*)(localHistData + idx);
                    }
                }
                mask += mstep_;
            }
        }

        lock.acquire(*histogramWriteLock_);
        for(int i = 0; i < histSize_.width*histSize_.height; i++)
        {
            ((int*)globalHistogram_)[i] += ((int*)localHistData)[i];
        }
        lock.release();
    }

    static bool isFit( const Mat& histogram, const Size imageSize )
    {
        return ( (histogram.total() > 4*4 &&  histogram.total() <= 116*116
                  && imageSize.width * imageSize.height >= 320*240)
                 || (histogram.total() > 116*116 && imageSize.width * imageSize.height >= 1280*720) );
    }

private:
    uchar* p_[two];
    uchar* mask_;
    int step_[two];
    int d_[two];
    int mstep_;
    int imageWidth_;
    Size histSize_;
    int histType_;
    size_t* tab_;
    tbb::mutex* histogramWriteLock_;
    uchar* globalHistogram_;
};

代码参考：opencv-3.4.1modulesimgprocsrchistogram.cpp

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