Rect函数

最新推荐文章于 2025-03-31 14:04:39 发布

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最新推荐文章于 2025-03-31 14:04:39 发布

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分类专栏： Opencv2.4.9_API

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本文详细介绍了OpenCV中Rect类的使用方法，包括构造函数、成员函数及操作符重载等，并提供了典型应用场景示例。

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了解opencv里面的函数，第一步必须是看官网上给出的文档。下面给出Rect类的c++使用。

class Rect_

 
  template<typename _Tp> class CV_EXPORTS Rect_
{
public:
    typedef _Tp value_type;

    //! various constructors
    Rect_();
    Rect_(_Tp _x, _Tp _y, _Tp _width, _Tp _height);
    Rect_(const Rect_& r);
    Rect_(const CvRect& r);
    Rect_(const Point_<_Tp>& org, const Size_<_Tp>& sz);
    Rect_(const Point_<_Tp>& pt1, const Point_<_Tp>& pt2);

    Rect_& operator = ( const Rect_& r );
    //! the top-left corner
    Point_<_Tp> tl() const;
    //! the bottom-right corner
    Point_<_Tp> br() const;

    //! size (width, height) of the rectangle
    Size_<_Tp> size() const;
    //! area (width*height) of the rectangle
    _Tp area() const;

    //! conversion to another data type
    template<typename _Tp2> operator Rect_<_Tp2>() const;
    //! conversion to the old-style CvRect
    operator CvRect() const;

    //! checks whether the rectangle contains the point
    bool contains(const Point_<_Tp>& pt) const;

    _Tp x, y, width, height; //< the top-left corner, as well as width and height of the rectangle
};
 
 

Template class for 2D rectangles, described by the following parameters:

Coordinates of the top-left corner. This is a default interpretation of Rect_::x and Rect_::y in OpenCV. Though, in your algorithms you may count x and y from the bottom-left corner.
Rectangle width and height.

OpenCV typically assumes that the top and left boundary of the rectangle are inclusive, while the right and bottom boundaries are not. For example, the method Rect_::contains returns true if

$x \leq pt.x < x+width, y \leq pt.y < y+height$

Virtually every loop over an image ROI in OpenCV (where ROI is specified by Rect_<int> ) is implemented as:

 
  for(int y = roi.y; y < roi.y + rect.height; y++)
    for(int x = roi.x; x < roi.x + rect.width; x++)
    {
        // ...
    }
 
 

In addition to the class members, the following operations on rectangles are implemented:

$\texttt{rect} = \texttt{rect} \pm \texttt{point}$ (shifting a rectangle by a certain offset)
$\texttt{rect} = \texttt{rect} \pm \texttt{size}$ (expanding or shrinking a rectangle by a certain amount)
rect += point, rect -= point, rect += size, rect -= size (augmenting operations)
rect = rect1 & rect2 (rectangle intersection)
rect = rect1 | rect2 (minimum area rectangle containing rect2 and rect3 )
rect &= rect1, rect |= rect1 (and the corresponding augmenting operations)
rect == rect1, rect != rect1 (rectangle comparison)

This is an example how the partial ordering on rectangles can be established (rect1 $\subseteq$ rect2):

 
  template<typename _Tp> inline bool
operator <= (const Rect_<_Tp>& r1, const Rect_<_Tp>& r2)
{
    return (r1 & r2) == r1;
}
 
 

For your convenience, the Rect_<> alias is available:

typedef Rect_<int> Rect;

在模板类中公有中，给出了许多的构造函数，可以任选一种作为你使用的函数。我常用的就是Rect(a,b,c,d)。(a,b)表示矩形区域的左上角坐标，（c,d）则表示矩形区域的右下角坐标。