/** @brief Returns a structuring element of the specified size and shape for morphological operations.The function constructs and returns the structuring element that can be further passed to cv::erode,
cv::dilate or cv::morphologyEx. But you can also construct an arbitrary binary mask yourself and use it as
the structuring element.@param shape Element shape that could be one of cv::MorphShapes
@param ksize Size of the structuring element.
@param anchor Anchor position within the element. The default value \f$(-1, -1)\f$ means that the
anchor is at the center. Note that only the shape of a cross-shaped element depends on the anchor
position. In other cases the anchor just regulates how much the result of the morphological
operation is shifted.*/
CV_EXPORTS_W Mat getStructuringElement(int shape, Size ksize, Point anchor = Point(-1,-1));

cv::Mat cv::getStructuringElement(int shape, Size ksize, Point anchor)
{int i, j;int r = 0, c = 0;double inv_r2 = 0;CV_Assert( shape == MORPH_RECT || shape == MORPH_CROSS || shape == MORPH_ELLIPSE );　　　　　　　　//目前支持三种形状的单元创建： 矩形， 十字形， 椭圆形；anchor = normalizeAnchor(anchor, ksize);　　　　　　　　　　　　　　　　　　　　//当默认为-1，-1时， 计算anchor;if( ksize == Size(1,1) )　　　　　　　　　　　　　　　　　　//当给定大小为1，1时，表明是一个点， 可以用矩形来表示；shape = MORPH_RECT;if( shape == MORPH_ELLIPSE )　　　　　　　　　　　　　　　//椭圆；{r = ksize.height/2;c = ksize.width/2;inv_r2 = r ? 1./((double)r*r) : 0;}Mat elem(ksize, CV_8U);for( i = 0; i < ksize.height; i++ )　　　　　　　　　　　　　　　　　　　　//对每一行，计算0，1的范围；{uchar* ptr = elem.ptr(i);int j1 = 0, j2 = 0;if( shape == MORPH_RECT || (shape == MORPH_CROSS && i == anchor.y) )　　　　　　　　//矩形，或十字y锚点时  j2为ksize.width;j2 = ksize.width;else if( shape == MORPH_CROSS )j1 = anchor.x, j2 = j1 + 1;else　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　//椭圆；{int dy = i - r;if( std::abs(dy) <= r ){int dx = saturate_cast<int>(c*std::sqrt((r*r - dy*dy)*inv_r2));　　　　　　　　//计算得到x的偏移；j1 = std::max( c - dx, 0 );j2 = std::min( c + dx + 1, ksize.width );}}for( j = 0; j < j1; j++ )　　　　　　　　　　　　　　　　//从这三个for可以看出, (0,j1)之间为 0,  (j1, j2)之间为1,  (j2, ksize.width)之间为0;ptr[j] = 0;for( ; j < j2; j++ )ptr[j] = 1;for( ; j < ksize.width; j++ )ptr[j] = 0;}return elem;
}