    // Copyright (C) 2015  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #undef DLIB_DRECTANGLe_ABSTRACT_H_
    #ifdef DLIB_DRECTANGLe_ABSTRACT_H_

    #include "rectangle_abstract.h"

    namespace dlib
    {

    // ----------------------------------------------------------------------------------------

        class drectangle
        {
            /*!
                INITIAL VALUE
                    The initial value of this object is defined by its constructor.

                WHAT THIS OBJECT REPRESENTS
                    This object is just like dlib::rectangle except that it stores the
                    coordinates of the rectangle using double rather than long variables.  As
                    such, this object represents a rectangular region inside an image.  The
                    region is the rectangle with its top left corner at position (left(),top())
                    and its bottom right corner at (right(),bottom()).

                    Note that the origin of the coordinate system, i.e. (0,0), is located at
                    the upper left corner.  That is, points such as (1,1) or (3,5) represent
                    locations that are below and to the right of the origin.

                    Also note that rectangles where top() > bottom() or left() > right()
                    represent empty rectangles.
            !*/
        public:

            drectangle (
            );
            /*!
                ensures
                    - #left() == 0
                    - #top() == 0
                    - #right() == -1
                    - #bottom() == -1
                    - #is_empty() == true
            !*/

            drectangle (
                double left_,
                double top_,
                double right_,
                double bottom_
            );
            /*!
                ensures
                    - #left() == left_
                    - #top() == top_
                    - #right() == right_
                    - #bottom() == bottom_
            !*/

            drectangle (
                const vector<double,2>& p
            );
            /*!
                ensures
                    - #left()   == p.x()
                    - #top()    == p.y()
                    - #right()  == p.x()
                    - #bottom() == p.y()
            !*/

            template <typename T, typename U>
            drectangle (
                const vector<T,2>& p1,
                const vector<U,2>& p2
            );
            /*!
                ensures
                    - #*this == drectangle(p1) + drectangle(p2)
            !*/

            drectangle (
                const drectangle& rect
            );
            /*!
                ensures
                    - #*this represents the same rectangle as rect
            !*/

            drectangle (
                const rectangle& rect
            );
            /*!
                ensures
                    - left()   == rect.left()
                    - top()    == rect.top()
                    - right()  == rect.right()
                    - bottom() == rect.bottom()
                    - dcenter(*this) == dcenter(rect)
                    - width() == rect.width()
                    - height() == rect.height()
            !*/

            operator rectangle (
            ) const;
            /*!
                ensures
                    - returns a rectangle where left(), top(), right(), and bottom() have been
                      rounded to the nearest integer values.
            !*/

            double left (
            ) const;
            /*!
                ensures
                    - returns the x coordinate for the left side of this rectangle
            !*/

            double& left (
            );
            /*!
                ensures
                    - returns a non-const reference to the x coordinate for the left side
                      of this rectangle
            !*/

            double top (
            ) const;
            /*!
                ensures
                    - returns the y coordinate for the top of this rectangle
            !*/

            double& top (
            );
            /*!
                ensures
                    - returns a non-const reference to the y coordinate for the
                      top of this rectangle
            !*/

            double right (
            ) const;
            /*!
                ensures
                    - returns the x coordinate for the right side of this rectangle
            !*/

            double& right (
            );
            /*!
                ensures
                    - returns a non-const reference to the x coordinate for the right
                      side of this rectangle
            !*/

            double bottom (
            ) const;
            /*!
                ensures
                    - returns the y coordinate for the bottom of this rectangle
            !*/

            double& bottom (
            );
            /*!
                ensures
                    - returns a non-const reference to the y coordinate for the bottom
                      of this rectangle
            !*/

            const vector<double,2> tl_corner (
            ) const;
            /*!
                ensures
                    - returns vector<double,2>(left(), top())
                      (i.e. returns the top left corner point for this rectangle)
            !*/

            const vector<double,2> bl_corner (
            ) const;
            /*!
                ensures
                    - returns vector<double,2>(left(), bottom())
                      (i.e. returns the bottom left corner point for this rectangle)
            !*/

            const vector<double,2> tr_corner (
            ) const;
            /*!
                ensures
                    - returns vector<double,2>(right(), top())
                      (i.e. returns the top right corner point for this rectangle)
            !*/

            const vector<double,2> br_corner (
            ) const;
            /*!
                ensures
                    - returns vector<double,2>(right(), bottom())
                      (i.e. returns the bottom right corner point for this rectangle)
            !*/

            double width (
            ) const;
            /*!
                ensures
                    - if (is_empty()) then
                        - returns 0
                    - else
                        - returns the width of this rectangle.
                          (i.e. right() - left() + 1)
            !*/

            double height (
            ) const;
            /*!
                ensures
                    - if (is_empty()) then
                        - returns 0
                    - else
                        - returns the height of this rectangle.
                          (i.e. bottom() - top() + 1)
            !*/

            double area (
            ) const;
            /*!
                ensures
                    - returns width()*height()
            !*/

            bool is_empty (
            ) const;
            /*!
                ensures
                    - if (top() > bottom() || left() > right()) then
                        - returns true
                    - else
                        - returns false
            !*/

            drectangle operator + (
                const drectangle& rhs
            ) const;
            /*!
                ensures
                    - if (rhs.is_empty() == false && this->is_empty() == false) then
                        - returns the smallest rectangle that contains both *this and
                          rhs.
                    - if (rhs.is_empty() == true && this->is_empty() == false) then
                        - returns *this
                    - if (rhs.is_empty() == false && this->is_empty() == true) then
                        - returns rhs
                    - if (rhs.is_empty() == true && this->is_empty() == true) then
                        - returns a rectangle that has is_empty() == true
            !*/

            drectangle intersect (
                const drectangle& rhs
            ) const;
            /*!
                ensures
                    - if (there is a region of intersection between *this and rhs) then
                        - returns a rectangle that represents the intersection of *this
                          and rhs.
                    - else
                        - returns a rectangle where is_empty() == true
            !*/

            bool contains (
                const vector<double,2>& p
            ) const;
            /*!
                ensures
                    - if (the point (p.x(),p.y()) is contained in this rectangle) then
                        - returns true
                    - else
                        - returns false
            !*/

            bool contains (
                const drectangle& rect
            ) const
            /*!
                ensures
                    - if (rect + *this == *this) then
                        - returns true
                          (i.e. returns true if *this contains the given rectangle)
                    - else
                        - returns false
            !*/

            drectangle& operator *= (
                const double& scale
            );
            /*!
                ensures
                    - performs: *this = *this*scale;
                    - returns #*this
            !*/

            drectangle& operator /= (
                const double& scale
            );
            /*!
                requires
                    - scale != 0
                ensures
                    - performs: *this = *this*(1.0/scale);
                    - returns #*this
            !*/

            drectangle& operator += (
                const dlib::vector<double,2>& p
            );
            /*!
                ensures
                    - performs: *this = *this + drectangle(p)
                    - returns #*this
            !*/

            bool operator== (
                const drectangle& rect
            ) const;
            /*!
                ensures
                    - if (top() == rect.top() && left() == rect.left() &&
                          right() == rect.right() && bottom() == rect.bottom()) then
                        - returns true
                    - else
                        - returns false
            !*/

            bool operator!= (
                const drectangle& rect
            ) const;
            /*!
                ensures
                    - returns !(*this == rect)
            !*/
        };

    // ----------------------------------------------------------------------------------------

        void serialize (
            const drectangle& item,
            std::ostream& out
        );
        /*!
            provides serialization support
        !*/

        void deserialize (
            drectangle& item,
            std::istream& in
        );
        /*!
            provides deserialization support
        !*/

    // ----------------------------------------------------------------------------------------

        std::ostream& operator<< (
            std::ostream& out,
            const drectangle& item
        );
        /*!
            ensures
                - writes item to out in the form "[(left, top) (right, bottom)]"
        !*/

    // ----------------------------------------------------------------------------------------

        std::istream& operator>>(
            std::istream& in,
            drectangle& item
        );
        /*!
            ensures
                - reads a drectangle from the input stream in and stores it in #item.  The data
                  in the input stream should be of the form [(left, top) (right, bottom)]
        !*/

    // ----------------------------------------------------------------------------------------

        vector<double,2> center (
            const drectangle& rect
        );
        /*!
            ensures
                - returns the center of the given rectangle
        !*/

    // ----------------------------------------------------------------------------------------

        vector<double,2> dcenter (
            const drectangle& rect
        );
        /*!
            ensures
                - returns the center of the given rectangle.  (Both center() and dcenter() are
                  identical when applied to drectangle objects)
        !*/

    // ----------------------------------------------------------------------------------------

        drectangle operator* (
            const drectangle& rect,
            const double& scale
        );
        /*!
            ensures
                - This function returns a rectangle that has the same center as rect but with
                  dimensions that are scale times larger.  That is, we return a new rectangle R
                  such that:
                    - center(R) == center(rect)
                    - R.right()-R.left() == (rect.right()-rect.left())*scale
                    - R.bottom()-R.top() == (rect.bottom()-rect.top())*scale
        !*/

    // ----------------------------------------------------------------------------------------

        drectangle operator* (
            const double& scale,
            const drectangle& rect
        );
        /*!
            ensures
                - returns rect*scale
        !*/

    // ----------------------------------------------------------------------------------------

        drectangle operator/ (
            const drectangle& rect,
            const double& scale
        );
        /*!
            ensures
                - returns rect*(1.0/scale)
        !*/

    // ----------------------------------------------------------------------------------------

        drectangle operator+ (
            const drectangle& r,
            const vector<double,2>& p
        );
        /*!
            ensures
                - returns r + drectangle(p)
                  (i.e. returns the rectangle that contains both r and p)
        !*/

    // ----------------------------------------------------------------------------------------

        drectangle operator+ (
            const vector<double,2>& p,
            const drectangle& r
        );
        /*!
            ensures
                - returns r + drectangle(p)
                  (i.e. returns the rectangle that contains both r and p)
        !*/

    // ----------------------------------------------------------------------------------------

        template <typename T>
        drectangle translate_rect (
            const drectangle& rect,
            const vector<T,2>& p
        );
        /*!
            ensures
                - returns a rectangle R such that:
                    - R.left()   == rect.left()   + p.x()
                    - R.right()  == rect.right()  + p.x()
                    - R.top()    == rect.top()    + p.y()
                    - R.bottom() == rect.bottom() + p.y()
        !*/

    // ----------------------------------------------------------------------------------------

        drectangle intersect (
            const drectangle& a,
            const drectangle& b
        );
        /*!
            ensures
                - returns a.intersect(b)
                  (i.e. returns a rectangle representing the intersection of a and b)
        !*/

    // ----------------------------------------------------------------------------------------

        double area (
            const drectangle& a
        );
        /*!
            ensures
                - returns a.area()
        !*/

    // ----------------------------------------------------------------------------------------

        drectangle centered_drect (
            const vector<double,2>& p,
            double width,
            double height
        );
        /*!
            ensures
                - returns a rectangle R such that:
                    - center(R) == p
                    - if (width < 1 || height < 1)
                        - R.width() == 0
                        - R.height() == 0
                        - R.is_empty() == true
                    - else
                        - R.width() == width
                        - R.height() == height
        !*/

    // ----------------------------------------------------------------------------------------

        drectangle centered_drect (
            const drectangle& rect,
            double width,
            double height
        );
        /*!
            ensures
                - returns centered_drect(center(rect), width, height)
        !*/

    // ----------------------------------------------------------------------------------------

        const drectangle shrink_rect (
            const drectangle& rect,
            double num
        );
        /*!
            ensures
                - returns drectangle(rect.left()+num, rect.top()+num, rect.right()-num, rect.bottom()-num)
                  (i.e. shrinks the given drectangle by shrinking its border by num)
        !*/

    // ----------------------------------------------------------------------------------------

        const drectangle grow_rect (
            const drectangle& rect,
            double num
        );
        /*!
            ensures
                - return shrink_rect(rect, -num)
                  (i.e. grows the given drectangle by expanding its border by num)
        !*/

    // ----------------------------------------------------------------------------------------

        const drectangle shrink_rect (
            const drectangle& rect,
            double width,
            double height
        );
        /*!
            ensures
                - returns drectangle(rect.left()+width, rect.top()+height, rect.right()-width, rect.bottom()-height)
                  (i.e. shrinks the given drectangle by shrinking its left and right borders by width
                  and its top and bottom borders by height. )
        !*/

    // ----------------------------------------------------------------------------------------

        const drectangle grow_rect (
            const drectangle& rect,
            double width,
            double height
        );
        /*!
            ensures
                - return shrink_rect(rect, -width, -height)
                  (i.e. grows the given drectangle by expanding its border)
        !*/

    // ----------------------------------------------------------------------------------------

        const drectangle scale_rect (
            const drectangle& rect,
            double scale
        );
        /*!
            requires
                - scale > 0
            ensures
                - return drectangle(rect.left() * scale, rect.top() * scale, rect.right() * scale, rect.bottom() * scale)
                  (i.e. resizes the given rectangle by multiplying all side coordinates with a scale factor)
        !*/

    // ----------------------------------------------------------------------------------------

        drectangle set_rect_area (
            const drectangle& rect,
            double area
        );
        /*!
            requires
                - area >= 0
            ensures
                - Returns a rectangle R such that:
                    - center(R) == center(rect)
                    - R has the same aspect ratio as rect.  If rect.area() == 0 then the
                      returned rect has a 1:1 aspect ratio.
                    - R.area() == area
        !*/

    // ----------------------------------------------------------------------------------------

        drectangle set_aspect_ratio (
            const drectangle& rect,
            double ratio
        );
        /*!
            requires
                - ratio > 0
            ensures
                - This function reshapes the given rectangle so that it has the given aspect
                  ratio.  In particular, this means we return a rectangle R such that the
                  following equations are true:
                    - R.width()/R.height() == ratio
                    - R.area() == rect.area()
                    - dcenter(rect) == dcenter(R)
        !*/

    // ----------------------------------------------------------------------------------------

    }

    #endif // DLIB_DRECTANGLe_ABSTRACT_H_