OpenCV Rect_＜ _Tp ＞模版类详解及其成员函数用法示例

OpenCV Rect_< _Tp > 模版类是一个2维矩形模板类，其英文全称为Rect_< _Tp > Class Template Reference，其公有成员函数有以下几个：

其公有属性有：

Rect_< _Tp > 模版类以左上角点tl，坐标_Tp x,Tp y及矩形宽度及矩形高度来描述一个矩形。有了矩形的基本属性，就可获得其他属性。如右下角点br（用两点构造一个矩形，默认这两个点是其对角点），矩形的size，矩形的面积等，也可判定一个点是否在矩形内。另外矩形还可以执行一下操作：

rect = rect ± point；//将矩形移动一定的偏移量

rect = rect ±s ize；//将矩形扩大或缩小一定量

rect += point；

rect -= point；

rect += size；

rect -= size ；

rect = rect1 & rect2；//求矩形相交部分(即相互叠加部分)

rect = rect1 | rect2; //同时包含 rect1 和 rect2 的最小面积矩形

rect &= rect1,;

rect |= rect1;

bool b1 = (rect1 == rect2); //比较判断

bool b2 = (rect1 != rect2); //比较判断

因C++的基本数据类型有:int,flot,double等，OpenCV中有定义相应的Rect，如下：

typedef Rect_<int> cv::Rect2i

typedef Rect2i cv::Rect

typedef Rect_<double> cv::Rect2d

typedef Rect_<float> cv::Rect2f

常用的Rect实际上是矩形模板类实例化int的类。

示例程序

下面新建一个控制台应用程序，来演示矩形创建及其他成员函数的用法。其代码如下：

#include <iostream>
#include <opencv2/opencv.hpp>using namespace cv;
using namespace std;int main()
{Rect rec[8];Point pts[3];pts[0].x = 30;pts[0].y = 30;pts[1].x = 230;pts[1].y = 130;pts[2].x = 80;pts[2].y = 80;rec[1] = Rect(pts[0], Size(150, 100));//test constructor and "= "operatrorrec[2] = Rect(80,80, 150,80);         //test constructor and" = "operatrorrec[3] = Rect(pts[2], pts[1]);        //ttest constructor and" = "operatrorcout << "rec[1] width = " << rec[1].width << endl;cout << "rec[1] height = " << rec[1].height << endl;cout << "rec[1] area = " << rec[1].area() << endl;cout << "rec[1] top left corner: " << rec[1].tl() << endl;cout << "rec[1] bottom left corner: " << rec[1].br() << endl;if (rec[1].contains(pts[2])) //test contiains functioncout << "rec[1] contins pts[2] " << endl;else{cout << "rec[1] does not contin pts[2] " << endl;}rec[4] = rec[1] & rec[2]; //test" &" operaterif (rec[4].empty())cout << " There is not intersection between rec[1] and rec[2]" << endl;else{cout << "rec[4] width = " << rec[4].width << endl;cout << "rec[4] height = " << rec[4].height << endl;cout << "rec[4] area = " << rec[4].area() << endl;cout << "rec[4] top left corner: " << rec[4].tl() << endl;cout << "rec[4] bottom left corner: " << rec[4].br() << endl;}rec[5] = rec[1] | rec[2]; // test "|" operaterif (rec[5].empty())cout << "rec[5] is empty" << endl;else{cout << "rec[5] width = " << rec[5].width << endl;cout << "rec[5] height = " << rec[5].height << endl;cout << "rec[5] area = " << rec[5].area() << endl;cout << "rec[5] top left corner: " << rec[5].tl() << endl;cout << "rec[5] bottom left corner: " << rec[5].br() << endl;}rec[6] = rec[1] + Size(100, 100);cout << "rec[6] width = " << rec[6].width << endl;cout << "rec[6] height = " << rec[6].height << endl;cout << "rec[6] area = " << rec[6].area() << endl;cout << "rec[6] top left corner: " << rec[6].tl() << endl;cout << "rec[6] bottom left corner: " << rec[6].br() << endl;rec[7] = rec[1] + Point(50,50);cout << "rec[7] width = " << rec[7].width << endl;cout << "rec[7] height = " << rec[7].height << endl;cout << "rec[7] area = " << rec[7].area() << endl;cout << "rec[7] top left corner: " << rec[7].tl() << endl;cout << "rec[7] bottom left corner: " << rec[7].br() << endl;waitKey(0);
}

本博文到此结束。