opencv 鼠标选取ROI图像

参考摘自《learn opencv-如何在OpenCV中选择边界框（ROI）？》https://blog.csdn.net/wc781708249/article/details/78518447

左键拉框，空格或enter结束。但只能取【1】个ROI。

#include 
#include "opencv2/video/tracking.hpp"	// selectROI is part of tracking API

using namespace std;
using namespace cv;

int main(int argc, char **arv)
{
	Mat im = imread("E:/mypic/0.jpg");

	Rect2d roi_img = selectROI(im);		// Select ROI	
	Mat imCrop = im(roi_img);			// Crop image	
	imshow("Image", imCrop);			// Display Cropped Image
	
	
	waitKey(0);
	return 0;
}