一、理论

 

二、代码演示 

#include<opencv2\opencv.hpp>
#include<iostream>
#include<math.h>
using namespace cv;
using namespace std;
Mat bgImage;
const char* drawdemo_win = "draw shapes and text demo";
void MyLines();
void MyRectangle();
void MyEllipse();
void MyCircle();
void MyPolygon();
void RandomLineDemo();
int main(int argc,char** argv)
{bgImage= imread("E:\\vs2015\\opencvstudy\\3.jpg", 1);if (!bgImage.data){cout << "could not load image1!" << endl;return -1;}MyLines();MyRectangle();MyEllipse();MyCircle();MyPolygon();RandomLineDemo();putText(bgImage, "Hello World", Point(350, 200), CV_FONT_HERSHEY_SCRIPT_COMPLEX,4, Scalar(0, 200, 200), 4, LINE_8);imshow(drawdemo_win, bgImage);waitKey(0);return 0;
}
void MyLines()
{Point p1 = Point(20, 20);Point p2;p2.x = 800;p2.y = 800;Scalar color = (0, 0, 255);line(bgImage, p1, p2, color, 1, LINE_AA);  //在图上画线..LINE_AA 代表反锯齿
}void MyRectangle()
{Rect rect = Rect(500, 500, 300, 300);Scalar color = (255, 0, 0);rectangle(bgImage, rect, color, 2, LINE_4);
}void MyEllipse()
{ellipse(bgImage, Point(bgImage.cols/2, bgImage.rows/2), Size(bgImage.cols / 4, 
bgImage.rows /8),90,0,360, Scalar(0, 255, 0), 2, LINE_8);// Point(x,y)代表椭圆中心点坐标 //Size（x,y）代表 长轴，短轴  // 90 代表椭圆的倾斜程度//0-360 代表椭圆的绘制弧度// Scalar(0, 255, 0) 椭圆颜色
}void MyCircle()
{Point p1 = Point(bgImage.cols / 2, bgImage.rows / 2);circle(bgImage, p1, 100, Scalar(255, 255, 0), 2, LINE_8);
}void MyPolygon()
{Point pts[1][5];pts[0][0] = Point(100, 100);pts[0][1] = Point(100, 200);pts[0][2] = Point(200, 200);pts[0][3] = Point(200, 100);pts[0][4] = Point(100, 100);const Point* ppts[] = { pts[0] };int nps[] = {5};Scalar color = Scalar(255, 12, 255);fillPoly(bgImage, ppts, nps, 1, color, LINE_8);  //1代表只有一个轮廓}void RandomLineDemo()
{RNG rng(12345);Point pt1;Point pt2;Mat bg = Mat::zeros(bgImage.size(), bgImage.type());for (int i = 0; i < 100000; i++){pt1.x = rng.uniform(0, bgImage.cols);pt2.x = rng.uniform(0, bgImage.cols);pt1.y = rng.uniform(0, bgImage.rows);pt2.y = rng.uniform(0, bgImage.rows);line(bg, pt1, pt2, Scalar(rng.uniform(0, 255), rng.uniform(0, 255), 
rng.uniform(0, 255)), 2, LINE_8);if (waitKey(50) > 0){break;}imshow("RandomLineDemo", bg);}}