作者：Steven
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功能函式

// 繪制圓角矩形
void DrawRotatedRectChamfer(cv::Mat mask,const cv::RotatedRect rotatedrect, float radius,const cv::Scalar &color, int thickness, int lineType)
{
	// 創建畫布
	cv::Mat canvas = cv::Mat::zeros(mask.size(), CV_8UC1);

	cv::RotatedRect newrotatedrect = rotatedrect;

	//畫寬縮減后的矩形
	cv::RotatedRect r1 = newrotatedrect;
	r1.size.width = r1.size.width - 2 * radius;
	DrawRotatedRect(canvas, r1, cv::Scalar(255), 5, lineType);

	//畫高縮減后的矩形
	cv::RotatedRect r2 = newrotatedrect;
	r2.size.height = r2.size.height - 2 * radius;
	DrawRotatedRect(canvas, r2, cv::Scalar(255), 5,lineType);

	//畫四個角的圓
	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

}

// 繪制旋轉矩形
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;    // 創建一個InputArrayOfArrays 型別的點集
	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
}

測驗代碼

#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;
}

// 繪制圓角矩形
void DrawRotatedRectChamfer(cv::Mat mask,const cv::RotatedRect rotatedrect, float radius,const cv::Scalar &color, int thickness, int lineType)
{
	// 創建畫布
	cv::Mat canvas = cv::Mat::zeros(mask.size(), CV_8UC1);

	cv::RotatedRect newrotatedrect = rotatedrect;

	//畫寬縮減后的矩形
	cv::RotatedRect r1 = newrotatedrect;
	r1.size.width = r1.size.width - 2 * radius;
	DrawRotatedRect(canvas, r1, cv::Scalar(255), 5, lineType);

	//畫高縮減后的矩形
	cv::RotatedRect r2 = newrotatedrect;
	r2.size.height = r2.size.height - 2 * radius;
	DrawRotatedRect(canvas, r2, cv::Scalar(255), 5,lineType);

	//畫四個角的圓
	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

}

// 繪制旋轉矩形
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;    // 創建一個InputArrayOfArrays 型別的點集
	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
}

測驗效果

繪制圓角矩形其實是繪制了兩個旋轉矩形，交叉組合，然后以四交點為圓心繪制圓，就組成了圓角矩形，如圖3所示，

同理，這個最好不要繪制到影像外面，否則它在分析外圍線的時候會出錯，可以多加些判斷來修正，我就不寫了，交給兄弟們研究一下~

如果文章幫助到你了，可以點個贊讓我知道，我會很快樂~加油！