使用c++實現(xiàn)OpenCV繪制圓端矩形

更新時間：2021年08月30日 17:25:23 作者：翟天保Steven

這篇文章主要介紹了使用c++實現(xiàn)OpenCV繪制圓端矩形，其中著重的講解了OpenCV使用過程中需要注意的一些小細節(jié)，避免浪費大家在開發(fā)過程中浪費多余的時間

功能函數(shù)

// 繪制圓端矩形（藥丸狀，pill）
void DrawPill(cv::Mat mask, const cv::RotatedRect &rotatedrect, const cv::Scalar &color, int thickness, int lineType)
{
	cv::Mat canvas = cv::Mat::zeros(mask.size(), CV_8UC1);
	// 確定短邊，短邊繪制圓形
	cv::RotatedRect rect = rotatedrect;
	float r = rect.size.height / 2.0f;
	if (rect.size.width > rect.size.height) {
		rect.size.width -= rect.size.height;
	}
	else {
		rect.size.height -= rect.size.width;
		r = rect.size.width / 2.0f;
	}
	cv::Point2f ps[4];
	rect.points(ps);
 
	// 繪制邊緣
	std::vector<std::vector<cv::Point>> tmpContours;
	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(canvas, tmpContours, 0, cv::Scalar(255),5, lineType);  // 填充mask
 	// 計算常長短軸
	float a = rotatedrect.size.width;
	float b = rotatedrect.size.height;
 	int point01_x = (int)((ps[0].x + ps[1].x) / 2.0f);
	int point01_y = (int)((ps[0].y + ps[1].y) / 2.0f);
	int point03_x = (int)((ps[0].x + ps[3].x) / 2.0f);
	int point03_y = (int)((ps[0].y + ps[3].y) / 2.0f);
	int point12_x = (int)((ps[1].x + ps[2].x) / 2.0f);
	int point12_y = (int)((ps[1].y + ps[2].y) / 2.0f);
	int point23_x = (int)((ps[2].x + ps[3].x) / 2.0f);
	int point23_y = (int)((ps[2].y + ps[3].y) / 2.0f);
 	cv::Point c0 = a < b ? cv::Point(point12_x, point12_y) : cv::Point(point23_x, point23_y);
	cv::Point c1 = a < b ? cv::Point(point03_x, point03_y) : cv::Point(point01_x, point01_y);
 	// 長軸兩端以填充的方式畫圓，直徑等于短軸
	cv::circle(canvas, c0, (int)r, cv::Scalar(255), 5, lineType);
	cv::circle(canvas, c1, (int)r, cv::Scalar(255), 5, lineType);
 	// 繪制外圍輪廓，如果不這樣操作，會得到一個矩形加兩個圓形，丑。。。
	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
}

測試代碼

#include <iostream>
#include <opencv2/opencv.hpp> 
using namespace std;
using namespace cv;
void DrawPill(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(1000, 800), 50);
	DrawPill(result, rorect, cv::Scalar(0, 255, 255),8,16);
	imshow("original", src);
	imshow("result", result);
	waitKey(0);
	return 0;
}
 // 繪制圓端矩形（藥丸狀，pill）
void DrawPill(cv::Mat mask, const cv::RotatedRect &rotatedrect, const cv::Scalar &color, int thickness, int lineType)
{
	cv::Mat canvas = cv::Mat::zeros(mask.size(), CV_8UC1);
	// 確定短邊，短邊繪制圓形
	cv::RotatedRect rect = rotatedrect;
	float r = rect.size.height / 2.0f;
	if (rect.size.width > rect.size.height) {
		rect.size.width -= rect.size.height;
	}
	else {
		rect.size.height -= rect.size.width;
		r = rect.size.width / 2.0f;
	}
	cv::Point2f ps[4];
	rect.points(ps);
 	// 繪制邊緣
	std::vector<std::vector<cv::Point>> tmpContours;
	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(canvas, tmpContours, 0, cv::Scalar(255),5, lineType);  // 填充mask
 	// 計算常長短軸
	float a = rotatedrect.size.width;
	float b = rotatedrect.size.height;
 	int point01_x = (int)((ps[0].x + ps[1].x) / 2.0f);
	int point01_y = (int)((ps[0].y + ps[1].y) / 2.0f);
	int point03_x = (int)((ps[0].x + ps[3].x) / 2.0f);
	int point03_y = (int)((ps[0].y + ps[3].y) / 2.0f);
	int point12_x = (int)((ps[1].x + ps[2].x) / 2.0f);
	int point12_y = (int)((ps[1].y + ps[2].y) / 2.0f);
	int point23_x = (int)((ps[2].x + ps[3].x) / 2.0f);
	int point23_y = (int)((ps[2].y + ps[3].y) / 2.0f);
	cv::Point c0 = a < b ? cv::Point(point12_x, point12_y) : cv::Point(point23_x, point23_y);
	cv::Point c1 = a < b ? cv::Point(point03_x, point03_y) : cv::Point(point01_x, point01_y);
 	// 長軸兩端以填充的方式畫圓，直徑等于短軸
	cv::circle(canvas, c0, (int)r, cv::Scalar(255), 5, lineType);
	cv::circle(canvas, c1, (int)r, cv::Scalar(255), 5, lineType);
 	// 繪制外圍輪廓，如果不這樣操作，會得到一個矩形加兩個圓形，丑。。。
	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
}