Opencv笔记（1）数据结构的命名规则（CvMat,...)

最新推荐文章于 2022-06-29 18:37:18 发布

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本文深入解析了OpenCV中CvMat结构体的定义及其相关函数cvMat(), cvmGet(), cvmSet()的工作原理，同时介绍了CvMatND和CvFileNode等核心数据结构。

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网上查了很多，发现查资料不如查源码

以Cv为开头的类，都是不含有具体数据的（仅仅存储指针）

CvMat

typedef struct CvMat
{
    int type;
    int step;

    /* for internal use only */
    int* refcount;
    int hdr_refcount;

    union
    {
        uchar* ptr;
        short* s;
        int* i;
        float* fl;
        double* db;
    } data;
<pre name="code" class="cpp">

#ifdef __cplusplus union { int rows; int height; }; union { int cols; int width; };#else int rows; int cols;#endif}CvMat;

<pre name="code" class="cpp">CV_INLINE CvMat cvMat( int rows, int cols, int type, void* data CV_DEFAULT(NULL))
{
    CvMat m;

    assert( (unsigned)CV_MAT_DEPTH(type) <= CV_64F );
    type = CV_MAT_TYPE(type);
    m.type = CV_MAT_MAGIC_VAL | CV_MAT_CONT_FLAG | type;
    m.cols = cols;
    m.rows = rows;
    m.step = m.cols*CV_ELEM_SIZE(type);
    m.data.ptr = (uchar*)data;
    m.refcount = NULL;
    m.hdr_refcount = 0;

    return m;
}

CV_INLINE  double  cvmGet( const CvMat* mat, int row, int col )
{／／低效率访问！
    int type;


    type = CV_MAT_TYPE(mat->type);
    assert( (unsigned)row < (unsigned)mat->rows &&
            (unsigned)col < (unsigned)mat->cols );


    if( type == CV_32FC1 )
        return ((float*)(void*)(mat->data.ptr + (size_t)mat->step*row))[col];
    else
    {
        assert( type == CV_64FC1 );
        return ((double*)(void*)(mat->data.ptr + (size_t)mat->step*row))[col];
    }
}




CV_INLINE  void  cvmSet( CvMat* mat, int row, int col, double value )
{
    int type;
    type = CV_MAT_TYPE(mat->type);
    assert( (unsigned)row < (unsigned)mat->rows &&
            (unsigned)col < (unsigned)mat->cols );


    if( type == CV_32FC1 )
        ((float*)(void*)(mat->data.ptr + (size_t)mat->step*row))[col] = (float)value;
    else
    {
        assert( type == CV_64FC1 );
        ((double*)(void*)(mat->data.ptr + (size_t)mat->step*row))[col] = (double)value;
    }
}

typedef struct CvMatND
{
    int type;
    int dims;


    int* refcount;
    int hdr_refcount;


    union
    {
        uchar* ptr;
        float* fl;
        double* db;
        int* i;
        short* s;
    } data;


    struct
    {
        int size;
        int step;
    }
    dim[CV_MAX_DIM];
}
CvMatND;

/* Basic element of the file storage - scalar or collection: */
typedef struct CvFileNode
{
    int tag;
    struct CvTypeInfo* info; /* type information
            (only for user-defined object, for others it is 0) */
    union
    {
        double f; /* scalar floating-point number */
        int i;    /* scalar integer number */
        CvString str; /* text string */
        CvSeq* seq; /* sequence (ordered collection of file nodes) */
        CvFileNodeHash* map; /* map (collection of named file nodes) */
    } data;
}
CvFileNode;