使用c++实现OpenCV绘制圆端矩形

功能函数

// 绘制圆端矩形(药丸状,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);

// 确定短边,短边绘制圆形

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);

// 绘制边缘

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

// 计算常长短轴

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);

// 长轴两端以填充的方式画圆,直径等于短轴

cv::circle(canvas, c0, (int)r, cv::Scalar(255), 5, lineType);

cv::circle(canvas, c1, (int)r, cv::Scalar(255), 5, lineType);

// 绘制外围轮廓,如果不这样操作,会得到一个矩形加两个圆形,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

}

测试代码

#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;

}

// 绘制圆端矩形(药丸状,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);

// 确定短边,短边绘制圆形

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);

// 绘制边缘

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

// 计算常长短轴

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);

// 长轴两端以填充的方式画圆,直径等于短轴

cv::circle(canvas, c0, (int)r, cv::Scalar(255), 5, lineType);

cv::circle(canvas, c1, (int)r, cv::Scalar(255), 5, lineType);

// 绘制外围轮廓,如果不这样操作,会得到一个矩形加两个圆形,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

}

测试效果 

 

图1 原图

图2 绘制圆端矩形

绘制圆端矩形其实就是绘制了一个旋转矩形,然后分析哪个轴更长,就在哪个轴上的两端画圆,再取外围轮廓,大功告成,通俗来讲就画了一个矩形两个圆,如图3所示。

 

图3 绘制逻

不过注意,这个图形最好不要超过图像边界,因为超过后再分析外围轮廓,它认为的外围就到了内部,如图4所示。

 图4 外围线

然后,你就会得到一个奇葩图形,如图5所示。

 

图5 示意图

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