图形绘制
图形填充

#include <opencv.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main(int argc, char** argv) {

    Mat canvas = Mat::zeros(Size(512, 512), CV_8UC3);
    
    namedWindow("canvas", WINDOW_NORMAL);
    imshow("canvas", canvas);
    //画线
    line(canvas, Point(0, 0), Point(400, 400), Scalar(0, 0, 255), 1, LINE_8);
    //画矩形
    Rect rect(100, 100, 200, 200);
    rectangle(canvas, rect, Scalar(255, 0, 0), 1, LINE_8, 0);
    //画圆
    circle(canvas, Point(300, 300), 100, Scalar(0, 255, 0), 1, LINE_8, 0);

    //文字
    putText(canvas, "hello opencv", Point(200, 50), FONT_HERSHEY_PLAIN, 1.0, Scalar(255, 0, 0), 2, 8);

    //椭圆 
    RotatedRect rrt;
    rrt.center = Point2f(256, 256);
    rrt.angle = CV_PI / 4;
    rrt.size = Size(100,200);
    ellipse(canvas, rrt, Scalar(0, 255, 255), -1, 8);//填充

    imshow("canvas", canvas);


    //随机画
    Mat image = Mat::zeros(Size(512, 512), CV_8UC3);

    int x1 = 0, y1 = 0;
    int x2 = 0, y2 = 0;
    RNG rng(12345);
    while (true) {
        x1 = (int)rng.uniform(0, 512);
        x2 = (int)rng.uniform(0, 512);
        y1 = (int)rng.uniform(0, 512);
        y2 = (int)rng.uniform(0, 512);
        int w = abs(x2 - x1);
        int h = abs(y2 - y1);
        rect.x = x1;
        rect.y = y1;
        rect.width = w;
        rect.height = h;

        line(image, Point(x1, y1), Point(x2, y2), Scalar(rng.uniform(0,256), rng.uniform(0, 256), rng.uniform(0, 256)), 1, LINE_8);
        rectangle(image, rect, Scalar(rng.uniform(0, 256), rng.uniform(0, 256), rng.uniform(0, 256)), 1, LINE_8, 0);
        imshow("image", image);
        char c = waitKey(10);
        if (c == 27) {
            break;
        }
    }


    waitKey(0);
    destroyAllWindows();
    return 0;
}

image.png

image.png