c++ 计算两个矩形重叠面积 （粗略版）（c++ calculate the overlap area of two rectangles, a rough version）

 1 #include <iostream>
 2 #include <opencv2/opencv.hpp>
 3 
 4 using namespace std;
 5 using namespace cv;
 6 
 7 int main()
 8 {
 9     // 1. 新建一个画布，把矩形画在画布上, 注意，矩形一定要在画布里面，不能在画布外面或者边上
10     Mat canvaCaluateRectangleOverlap(100, 100, CV_8UC1, Scalar(0, 0, 0));
11     
12     // 2. 把两个矩形都画在画布上
13     Rect rect1 = Rect(10, 10, 20, 20);
14     Rect rect2 = Rect(20, 20, 20, 30);
15     //为了使用fillPoly填充画布需要生成Point
16     Point rect1Point[1][4];
17     rect1Point[0][0] = Point(rect1.x, rect1.y);
18     rect1Point[0][1] = Point(rect1.x + rect1.width, rect1.y);
19     rect1Point[0][2] = Point(rect1.x + rect1.width, rect1.y + rect1.height);
20     rect1Point[0][3] = Point(rect1.x, rect1.y + rect1.height);
21 
22     // 以下是用轮廓法计算矩形面积的方法，可以看看，但是实际使用当然还是 width*height
23     //vector<Point> rect1Contours;
24     //rect1Contours.push_back(Point(20, 20));
25     //rect1Contours.push_back(Point(80, 20));
26     //rect1Contours.push_back(Point(80, 60));
27     //rect1Contours.push_back(Point(20, 60));
28     //int rect1ContourArea = contourArea(rect1Contours);
29     //cout << "rect1ContourArea : " << rect1ContourArea << endl;
30 
31     const Point* pointConst1[1] = { rect1Point[0] };
32     int npt[] = { 4 };
33     fillPoly(canvaCaluateRectangleOverlap, pointConst1, npt, 1, Scalar(255, 255, 255));
34 
35     Point rect2Point[1][4];
36     rect2Point[0][0] = Point(rect2.x, rect2.y);
37     rect2Point[0][1] = Point(rect2.x + rect2.width, rect2.y);
38     rect2Point[0][2] = Point(rect2.x + rect2.width, rect2.y + rect2.height);
39     rect2Point[0][3] = Point(rect2.x, rect2.y + rect2.height);
40     const Point* pointConst2[1] = { rect2Point[0] };
41     fillPoly(canvaCaluateRectangleOverlap, pointConst2, npt, 1, Scalar(255, 255, 255));
42 
43     // 3. 找出画布的轮廓
44     vector<vector<Point> > canvaContours;
45     vector<Vec4i> hierarchy;
46     findContours(canvaCaluateRectangleOverlap, canvaContours, hierarchy, RETR_EXTERNAL, CHAIN_APPROX_SIMPLE, Point(0, 0));
47     
48     // 修正结果的偏移量，会差1个或0个像素，这里不考虑这个，大家有时间可以列举出每种情况计算出来
49     int offset = 0;
50     // 4. 对画布轮廓进行判断 （如果轮廓数等于1并且这两个矩形不是相邻就可以证明矩形是相交的）
51     if (canvaContours.size() == 1 && rect1.x+rect1.width != rect2.x && rect2.x+rect2.width != rect1.x && rect1.y+rect1.height != rect2.y && rect2.y+rect2.height != rect1.y)
52     {
53         // 当矩形相交时，用计算轮廓面积的方法计算出相交多边形的面积（注意，这边会差0个或1个偏移量，所以本方式最适合计算重叠率，一个近似的数）
54         int canvaContourArea = contourArea(canvaContours[0]) + offset;
55         // 重叠的面积数 = 两个矩形面积的交集 - 两个矩形面积的并集 （要理解这个，好好去画图你就明白了）
56         int rectangleOveralpArea = rect1.width * rect1.height + rect2.width * rect2.height - canvaContourArea;
57         cout << "The two rectangles are overlapping. " << endl;
58         cout << "retangleOverlapArea = " << rectangleOveralpArea << endl;
59     }
60     else {
61         cout << "The two rectangles do not overlap. " << endl;
62     }
63     return 0;
64 }