opencv c++ （4）：图型绘制

1. 图形绘制

以下是几个绘制图形的api，细节不多说。值得注意的是指定线宽时候-1代表填充。

#include <iostream>
#include<opencv.hpp>
#include<opencv2\highgui\highgui.hpp>

using namespace std;
using namespace cv;
int main()
{
    
    
	Mat canvas = Mat::zeros(Size(512,512),CV_8UC3);

	//绘制
	//1. 线
	line(canvas, Point(10, 10), Point(400, 400), Scalar(0, 0, 255), 2, LINE_8);
	//2. 矩形
	Rect rect(100, 100, 200, 200);
	rectangle(canvas, rect,Scalar(255,0,0),2,8);
	//3. 圆
	circle(canvas, Point(256,256),100,Scalar(0,255,0),1,8);
	//4. 椭圆
	RotatedRect rrt;
	rrt.center = Point2f(256,256);
	rrt.angle = 45; //旋转45°
	rrt.size = Size(100,200);
	ellipse(canvas, rrt, Scalar(0, 100, 100), -1, 8);
	imshow("canvas", canvas);
	waitKey(0);
	destroyAllWindows();
	return 0;
}

2. 随机RNG

以下代码是在画布上随机画线段，这个看一下代码就懂。需要注意的是：指定退出键为esc，waitKey返回值为27代表按下的是esc，其他值可以看一下api中介绍，这里不详细说。

	Mat image = Mat::zeros(Size(512, 512), CV_8UC3);
	//rgn 种子初始化
	RNG rng(12345);
	//坐标
	int x1 = 0, y1 = 0, x2 = 0, y2 = 0;
	//颜色
	Scalar color = (0, 0, 0);
	while (1){
    
    

		x1 = (int)rng.uniform(0, 512);
		y1 = (int)rng.uniform(0, 512);
		x2 = (int)rng.uniform(0, 512);
		y2 = (int)rng.uniform(0, 512);

		color = Scalar(rng.uniform(0, 256), rng.uniform(0, 256), rng.uniform(0, 256));

		line(image, Point(x1, y1), Point(x2, y2), color, 1, 8);
		imshow("image", image);
		char c = waitKey(10);
		if (c == 27)
		{
    
    
			break;
		}

	}