OpenCV矩形rect的操作

OpenCV的Rect矩形类用法

    //如果创建一个Rect对象rect(100, 50, 50, 100)，那么rect会有以下几个功能：      rect.area();     //返回rect的面积 5000      rect.size();     //返回rect的尺寸 [50 × 100]      rect.tl();       //返回rect的左上顶点的坐标 [100, 50]      rect.br();       //返回rect的右下顶点的坐标 [150, 150]      rect.width();    //返回rect的宽度 50      rect.height();   //返回rect的高度 100      rect.contains(Point(x, y));  //返回布尔变量，判断rect是否包含Point(x, y)点      //还可以求两个矩形的交集和并集      rect = rect1 & rect2;      rect = rect1 | rect2;      //还可以对矩形进行平移和缩放        rect = rect + Point(-100, 100); //平移，也就是左上顶点的x坐标-100，y坐标+100      rect = rect + Size(-100, 100);  //缩放，左上顶点不变，宽度-100，高度+100      //还可以对矩形进行对比，返回布尔变量      rect1 == rect2;      rect1 != rect2;      //OpenCV里貌似没有判断rect1是否在rect2里面的功能，所以自己写一个吧      bool isInside(Rect rect1, Rect rect2)      {          return (rect1 == (rect1&rect2));      }      //OpenCV貌似也没有获取矩形中心点的功能，还是自己写一个      Point getCenterPoint(Rect rect)      {          Point cpt;          cpt.x = rect.x + cvRound(rect.width/2.0);          cpt.y = rect.y + cvRound(rect.height/2.0);          return cpt;      }      //围绕矩形中心缩放      Rect rectCenterScale(Rect rect, Size size)      {          rect = rect + size;           Point pt;          pt.x = cvRound(size.width/2.0);          pt.y = cvRound(size.height/2.0);          return (rect-pt);      }      再看Rect_的定义：

/*!
The 2D up-right rectangle class

The class represents a 2D rectangle with coordinates of the specified data type.
Normally, cv::Rect ~ cv::Rect_ is used.
*/
template class Rect_
{
public:
typedef _Tp value_type;

//! various constructorsRect_();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 cornerPoint_<_Tp> tl() const;//! the bottom-right cornerPoint_<_Tp> br() const;//! size (width, height) of the rectangleSize_<_Tp> size() const;//! area (width*height) of the rectangle_Tp area() const;//! conversion to another data typetemplate<typename _Tp2> operator Rect_<_Tp2>() const;//! conversion to the old-style CvRectoperator CvRect() const;//! checks whether the rectangle contains the pointbool contains(const Point_<_Tp>& pt) const;_Tp x, y, width, height; //< the top-left corner, as well as width and height of the rectangle

};

从上面的定义至少可以发现两点：一，类Rect_的类模板中的数据类型_Tp在Rect_<int>中被指定为整型；二，从Rect_的构造函数可以看出，其形参列表一共有6种形式：    Rect_()，形参列表为空，即定义一个空窗口（默认值为：x=y=width=height=0）；    Rect_(_Tp _x, _Tp _y, _Tp _width, _Tp _height)，定义一个左上角点坐标为(_x, _y)的_width*_height矩形窗口；    Rect_(const Rect_& r)，使用其他的Rect_对象初始化；    Rect_(const CvRect& r)，使用CvRect对象初始化；    Rect_(const Point_<_Tp>& org, const Size_<_Tp>& sz)，分别将位置坐标(_x, _y)和窗口大小(_width, _height)用Point_和Size_对象初始化；    Rect_(const Point_<_Tp>& pt1, const Point_<_Tp>& pt2)，分别将坐标位置(_x, _y)和窗口大小(_width, _height)用Point_和Point_对象初始化。    在OpenCV库中，图像像素坐标与所在行列数的对应关系为：x -> col, y -> row, width -> cols, height -> rows下面给出一段代码，基本可以把Rect的常见用法涵盖：

Mat image = imread(“C:\Users\Leo\Desktop\lena.jpg”);
Rect rect1(256, 256, 128, 128);
Rect rect2(224, 224, 128, 128);

Mat roi1;
image(rect1).copyTo(roi1); // copy the region rect1 from the image to roi1
imshow(“1”, roi1);
waitKey(0);

Mat roi2;
image(rect2).copyTo(roi2); // copy the region rect2 from the image to roi2
imshow(“2”, roi2);
waitKey(0);

cv::Rect rect3 = rect1&rect2; // intersection of the two sets
Mat roi3;
image(rect3).copyTo(roi3);
imshow(“3”, roi3);
waitKey(0);

Rect rect4 = rect1|rect2; // union of the two sets (the minimum bounding rectangle)
Mat roi4;
image(rect4).copyTo(roi4);
imshow(“4”, roi4);
waitKey(0);

Rect rect5(10, 10, 128, 128);
roi1.copyTo(image(rect5)); // copy the region rect1 to the designated region in the image
imshow(“5”, image);
waitKey(0);
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