OPENCV using RECT to select and set window ROI

This series of articles by the @yhl_leo produced, reproduced please indicate the source.
Article Link: http://blog.csdn.net/yhl_leo/article/details/50593825

First look at the definition of the Rect object:

typedef rect_<int> Rect;

Then look at the definition of rect_:

/*!
  The 2D up-right Rectangle Class The class represents a 2D rectangle with coordinates of the specified data type.
Normally, Cv::rect ~ cv::rect_<int> is used.

    */Template<typename _tp> class Rect_ {public:typedef _tp value_type; //!
    Various constructors rect_ ();
    Rect_ (_tp _x, _tp _y, _tp _width, _tp _height);
    Rect_ (const rect_& R);
    Rect_ (const cvrect& R);
    rect_ (const point_<_tp>& org, const size_<_tp>& SZ);

    Rect_ (const point_<_tp>& PT1, const point_<_tp>& PT2);
    rect_& operator = (const rect_& r); //!
    The Top-left corner point_<_tp> TL () const; //!

    The bottom-right corner point_<_tp> BR () const; //!
    Size (width, height) of the rectangle size_<_tp> Size () const; //!

    Area (width*height) of the rectangle _TP area () const; //! Conversion to another data type Template<typename _tp2> operator rect_<_tp2>() const; //!

    Conversion to the Old-style cvrect operator cvrect () const; //!

    Checks whether the rectangle contains the point bool contains (const point_<_tp>& PT) const; _tp x, y, width, height; < The Top-left corner, as well as width and height of the rectangle};

From the above definition can be found at least two points: first, the class Rect_ class template data type _TP in rect_<int> is specified as integral type, two, from the Rect_ constructor can be seen, its formal parameter list has 6 forms: rect_ (), parameter list is empty, That is, define an empty window (the default is: x=y=width=height=0), rect_ (_tp _x, _tp _y, _tp _width, _tp _height), define a _x for the upper-left corner point coordinates (_y, _width*_) Height Rectangle window; rect_ (const rect_& R), initialized with other rect_ objects, rect_ (const cvrect& R), initialized with Cvrect object, rect_ (const POINT_ <_Tp>& org, const size_<_tp>& SZ), initializes the position coordinates (_x, _y) and the window size (_width, _height) with Point_ and Size_ objects, respectively; Rect_ ( Const point_<_tp>& PT1, const point_<_tp>& pt2), respectively, coordinates the location (_x, _y) and window size (_width, _height) with Point_ and Point_ object initialization.

In the OpenCV library, the corresponding relationship between the pixel coordinates of the image and the number of rows is: X, col, y, row, width, cols, height, rows

Here's a piece of code that basically covers the common uses of rect:

Mat image = Imread ("c:\\users\\leo\\desktop\\lena.jpg");
Rect rect1 (n. ();
Rect Rect2 (224, 224, N.);

Mat Roi1;
Image (Rect1). CopyTo (ROI1); Copy the region Rect1 from the image to Roi1
imshow ("1", roi1);
Waitkey (0);

Mat Roi2;
Image (Rect2). CopyTo (ROI2); Copy the region Rect2 from the image to Roi2
imshow ("2", roi2);
Waitkey (0);

Cv::rect rect3 = rect1&rect2; Intersection of the sets
Mat roi3;
Image (RECT3). CopyTo (ROI3);
Imshow ("3", roi3);
Waitkey (0);

Rect rect4 = Rect1|rect2; Union of the sets (the minimum bounding rectangle)
Mat roi4;
Image (Rect4). CopyTo (ROI4);
Imshow ("4", roi4);
Waitkey (0);

Rect Rect5 (Ten, ten, +);
Roi1.copyto (Image (RECT5)); Copy the region Rect1
to the designated region in the image Imshow ("5", image);
Waitkey (0);

The result is:

The corresponding code can be downloaded from the GitHub account: Yhlleo.