前言
最近看github上源码发现对两个cv::Rect使用相与(&)操作,猛地感觉自己蒙啦,Rect类还有这种神奇用法?!翻看opencv官网Rect类,果然如此!
opencv中Rect类
Rect_类有些意思,成员变量x、y、width、height,分别为左上角点的坐标和矩形的宽和高。常用的成员函数有Size()返回值为一个Size,area()返回矩形的面积,contains(Point)用来判断点是否在矩形内,inside(Rect)函数判断矩形是否在该矩形内,tl()返回左上角点坐标,br()返回右下角点坐标。
Rect类的使用
- rect = rect ± point (shifting a rectangle by a certain offset)
- rect = rect ± size (expanding or shrinking a rectangle by a certain amount)
- rect += point, rect -= point, rect += size, rect -= size (augmenting operations)
- rect = rect1 & rect2 (rectangle intersection)
- rect = rect1 | rect2 (minimum area rectangle containing rect1 and rect2 )
- rect &= rect1, rect |= rect1 (and the corresponding augmenting operations)
- rect == rect1, rect != rect1 (rectangle comparison)
两个矩形的交并
Rect rect = rect1 & rect2;
Rect rect = rect1 | rect2;
两个矩形的平移或者缩放
Rect rectShift = rect + point;
Rect rectScale = rect + size;
all usage
//如果创建一个Rect对象rect(100, 50, 50, 100),那么rect会有以下几个功能: rect.area(); //返回rect的面积 5000 rect.size(); //返回rect的尺寸 [50 × 100] rect.tl(); //返回rect的左上顶点的坐标 [100, 50] rect.br(); //返回rect的右下顶点的坐标 [150, 150] rect.width(); //返回rect的宽度 50 rect.height(); //返回rect的高度 100 rect.contains(Point(x, y)); //返回布尔变量,判断rect是否包含Point(x, y)点 //还可以求两个矩形的交集和并集 rect = rect1 & rect2; rect = rect1 | rect2; //还可以对矩形进行平移和缩放 rect = rect + Point(-100, 100); //平移,也就是左上顶点的x坐标-100,y坐标+100 rect = rect + Size(-100, 100); //缩放,左上顶点不变,宽度-100,高度+100 //还可以对矩形进行对比,返回布尔变量 rect1 == rect2; rect1 != rect2; //OpenCV里貌似没有判断rect1是否在rect2里面的功能,所以自己写一个吧 bool isInside(Rect rect1, Rect rect2) { return (rect1 == (rect1&rect2)); } //OpenCV貌似也没有获取矩形中心点的功能,还是自己写一个 Point getCenterPoint(Rect rect) { Point cpt; cpt.x = rect.x + cvRound(rect.width/2.0); cpt.y = rect.y + cvRound(rect.height/2.0); return cpt; } //围绕矩形中心缩放 Rect rectCenterScale(Rect rect, Size size) { rect = rect + size; Point pt; pt.x = cvRound(size.width/2.0); pt.y = cvRound(size.height/2.0); return (rect-pt); }
参考
完