//2020.6.21_P77_OpenCV投影变换
//通过鼠标事件在原图和输出的画布上选取四组对应的坐标
//投影矩阵的数据类型为CV_64F
//txwtech

//2020.6.21_P77_OpenCV投影变换
//通过鼠标事件在原图和输出的画布上选取四组对应的坐标
//投影矩阵的数据类型为CV_64F
//txwtech
#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
using namespace cv;

Mat I;
Mat pI;
Point2f IPoint, pIPoint;
int i = 0, j = 0;
Point2f src[4];
Point2f dst[4];
void mouse_I(int event, int x, int y, int flags, void *param)
{
	switch (event)
	{
	case CV_EVENT_LBUTTONDOWN:
			IPoint = Point2f(x,y);
			break;
	case CV_EVENT_LBUTTONUP:
		    src[i] = IPoint;
			circle(I,src[i],7,Scalar(0),3);
			i += 1;
			break;
	default:
		break;



	}
}
void mouse_pI(int event, int x, int y, int flags, void *param)
{
	switch (event)
	{
	case CV_EVENT_LBUTTONDOWN:
		pIPoint = Point2f(x,y);
		break;
	case CV_EVENT_LBUTTONUP:
		dst[j] = pIPoint;
		circle(pI,dst[j],7,Scalar(0),3);
		j += 1;
		break;
	default:
		break;
	}
}
int main(int argc, char *agrv[])
{
	I = imread("D:\\pictures\\book1.jpg",CV_LOAD_IMAGE_GRAYSCALE);
	if (!I.data)
		return -1;
	pI = 255*Mat::ones(I.size(),CV_8UC1);
	namedWindow("I",1); //window auto size=1
	setMouseCallback("I",mouse_I,NULL);
	namedWindow("pI",1);
	
	setMouseCallback("pI",mouse_pI,NULL);
	imshow("I",I);
	imshow("pI",pI);
	while (!(i == 4 && j == 4))
	{
		imshow("I",I);//原图
		imshow("pI",pI);//投影变换后的图
		if (waitKey(50) == 'q')
			break;
	}
	imshow("I",I);
	imshow("pI",pI);
	setMouseCallback("I",NULL,NULL);
	setMouseCallback("pI", NULL, NULL);
	Mat p = getPerspectiveTransform(src,dst);//计算投影变换矩阵
	Mat result;
	warpPerspective(I,result,p,pI.size());//投影变换
	imshow("投影后的效果",result);
	waitKey(0);
	return 0;

}