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    OpenCV绘制圆角矩形的方法实例

    作者:翟天保Steven 时间:2021-09-15 18:31

    功能函数

    // 绘制圆角矩形
    void DrawRotatedRectChamfer(cv::Mat mask,const cv::RotatedRect rotatedrect, float radius,const cv::Scalar &color, int thickness, int lineType)
    {
    	// 创建画布
    	cv::Mat canvas = cv::Mat::zeros(mask.size(), CV_8UC1);
     
    	cv::RotatedRect newrotatedrect = rotatedrect;
     
    	//画宽缩减后的矩形
    	cv::RotatedRect r1 = newrotatedrect;
    	r1.size.width = r1.size.width - 2 * radius;
    	DrawRotatedRect(canvas, r1, cv::Scalar(255), 5, lineType);
     
    	//画高缩减后的矩形
    	cv::RotatedRect r2 = newrotatedrect;
    	r2.size.height = r2.size.height - 2 * radius;
    	DrawRotatedRect(canvas, r2, cv::Scalar(255), 5,lineType);
     
    	//画四个角的圆
    	cv::RotatedRect r3 = r2;
    	r3.size.width = r1.size.width;
     
    	cv::Point2f ps[4];
    	r3.points(ps);
     
    	for (int i = 0; i != 4; ++i) {
    		cv::circle(canvas, ps[i], (int)radius, cv::Scalar(255), 5);
    	}
    	std::vector<std::vector<cv::Point>> EXcontours;
    	cv::findContours(canvas, EXcontours, cv::RETR_EXTERNAL, CHAIN_APPROX_SIMPLE);
    	drawContours(mask, EXcontours, 0, color, thickness, lineType);  // 填充mask
     
    }
     
    // 绘制旋转矩形
    void DrawRotatedRect(cv::Mat mask,const cv::RotatedRect rotatedrect,const cv::Scalar &color, int thickness,int lineType)
    {
    	cv::Point2f ps[4];
    	rotatedrect.points(ps);
     
    	std::vector<std::vector<cv::Point>> tmpContours;    // 创建一个InputArrayOfArrays 类型的点集
    	std::vector<cv::Point> contours;
    	for (int i = 0; i != 4; ++i) {
    		contours.emplace_back(cv::Point2i(ps[i]));
    	}
    	tmpContours.insert(tmpContours.end(), contours);
    	drawContours(mask, tmpContours, 0, color, thickness, lineType);  // 填充mask
    }

    测试代码

    #include <iostream>
    #include <opencv2/opencv.hpp>
    #include <stdio.h>
    using namespace std;
    using namespace cv;
     
    void DrawRotatedRectChamfer(cv::Mat mask, const cv::RotatedRect rotatedrect, float radius, const cv::Scalar &color, int thickness, int lineType);
    void DrawRotatedRect(cv::Mat mask, const cv::RotatedRect rotatedrect, const cv::Scalar &color, int thickness, int lineType);
     
    int main()
    {
    	cv::Mat src = imread("test.jpg");
    	cv::Mat result = src.clone();
    	cv::RotatedRect rorect(cv::Point(src.cols / 2, src.rows / 2), cv::Size(800, 600), 50);
    	DrawRotatedRectChamfer(result, rorect, 100, cv::Scalar(0, 0, 255), 5, 16);
    	imshow("original", src);
    	imshow("result", result);
    	waitKey(0);
    	return 0;
    }
     
    // 绘制圆角矩形
    void DrawRotatedRectChamfer(cv::Mat mask,const cv::RotatedRect rotatedrect, float radius,const cv::Scalar &color, int thickness, int lineType)
    {
    	// 创建画布
    	cv::Mat canvas = cv::Mat::zeros(mask.size(), CV_8UC1);
     
    	cv::RotatedRect newrotatedrect = rotatedrect;
     
    	//画宽缩减后的矩形
    	cv::RotatedRect r1 = newrotatedrect;
    	r1.size.width = r1.size.width - 2 * radius;
    	DrawRotatedRect(canvas, r1, cv::Scalar(255), 5, lineType);
     
    	//画高缩减后的矩形
    	cv::RotatedRect r2 = newrotatedrect;
    	r2.size.height = r2.size.height - 2 * radius;
    	DrawRotatedRect(canvas, r2, cv::Scalar(255), 5,lineType);
     
    	//画四个角的圆
    	cv::RotatedRect r3 = r2;
    	r3.size.width = r1.size.width;
     
    	cv::Point2f ps[4];
    	r3.points(ps);
     
    	for (int i = 0; i != 4; ++i) {
    		cv::circle(canvas, ps[i], (int)radius, cv::Scalar(255), 5);
    	}
    	std::vector<std::vector<cv::Point>> EXcontours;
    	cv::findContours(canvas, EXcontours, cv::RETR_EXTERNAL, CHAIN_APPROX_SIMPLE);
    	drawContours(mask, EXcontours, 0, color, thickness, lineType);  // 填充mask
     
    }
     
    // 绘制旋转矩形
    void DrawRotatedRect(cv::Mat mask,const cv::RotatedRect rotatedrect,const cv::Scalar &color, int thickness,int lineType)
    {
    	cv::Point2f ps[4];
    	rotatedrect.points(ps);
     
    	std::vector<std::vector<cv::Point>> tmpContours;    // 创建一个InputArrayOfArrays 类型的点集
    	std::vector<cv::Point> contours;
    	for (int i = 0; i != 4; ++i) {
    		contours.emplace_back(cv::Point2i(ps[i]));
    	}
    	tmpContours.insert(tmpContours.end(), contours);
    	drawContours(mask, tmpContours, 0, color, thickness, lineType);  // 填充mask
    }

    测试效果

    图1 原图

    图2 绘制圆角矩形

    绘制圆角矩形其实是绘制了两个旋转矩形,交叉组合,然后以四交点为圆心绘制圆,就组成了圆角矩形,如图3所示。


    图3 绘制逻辑

    同理,这个最好不要绘制到图像外面,否则它在分析外围线的时候会出错,可以多加些判断来修正,我就不写了,交给兄弟们研究一下~

    总结

    jsjbwy
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