samples/cpp/minarea.cpp

#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
 
#include <iostream>
 
using namespace cv;
using namespace std;
 
static void help()
{
cout << "此程序演示如何查找一组点集合的最小包围框、三角形或圆形，\n"
<< "使用的函数：minAreaRect() minEnclosingTriangle() minEnclosingCircle()。\n"
<< "生成随机点然后进行封闭。\n\n"
<< "按 ESC，'q' 或 'Q' 退出，按其他任意键重新生成这一组点。\n\n";
}
 
int main( int /*argc*/, char** /*argv*/ )
{
help();
 
    Mat img(500, 500, CV_8UC3, Scalar::all(0));
    RNG& rng = theRNG();
 
    for(;;)
    {
        int i, count = rng.uniform(1, 101);
vector<Point> points;
 
        // 生成一组随机点
        for( i = 0; i < count; i++ )
        {
            Point pt;
pt.x = rng.uniform(img.cols/4, img.cols*3/4);
pt.y = rng.uniform(img.rows/4, img.rows*3/4);
 
points.push_back(pt);
        }
 
        // 查找最小面积的包围的矩形框
        Point2f vtx[4];
        RotatedRect box = minAreaRect(points);
box.points(vtx);
 
        // 查找最小面积的包围的三角形
vector<Point2f> triangle;
        minEnclosingTriangle(points, triangle);
 
        // 查找最小外接圆
        Point2f center;
        float radius = 0;
        minEnclosingCircle(points, center, radius);
 
img = Scalar::all(0);
 
        // 绘制点
        for( i = 0; i < count; i++ )
            circle( img, points[i], 3, Scalar(0, 0, 255), FILLED, LINE_AA );
 
        // 绘制边界框
        for( i = 0; i < 4; i++ )
            line(img, vtx[i], vtx[(i+1)%4], Scalar(0, 255, 0), 1, LINE_AA);
 
        // 绘制三角形
        for( i = 0; i < 3; i++ )
            line(img, triangle[i], triangle[(i+1)%3], Scalar(255, 255, 0), 1, LINE_AA);
 
        // 绘制圆形
        circle(img, center, cvRound(radius), Scalar(0, 255, 255), 1, LINE_AA);
 
        imshow( "矩形、三角形和圆形", img );
 
        char key = (char)waitKey();
        if( key == 27 || key == 'q' || key == 'Q' ) // 'ESC'
            break;
    }
 
    return 0;
}