    // Copyright (C) 2011  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #undef DLIB_DETECTION_TEMPlATE_TOOLS_ABSTRACT_H__
    #ifdef DLIB_DETECTION_TEMPlATE_TOOLS_ABSTRACT_H__

    #include "../geometry.h"
    #include <utility>
    #include <vector>

    namespace dlib
    {

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

        rectangle compute_box_dimensions (
            const double width_to_height_ratio,
            const double area
        );
        /*!
            requires
                - area > 0
                - width_to_height_ratio > 0
            ensures
                - returns a rectangle with the given area and width_to_height_ratio.
                - In particular, returns a rectangle R such that:
                    - R.area() == area (to within integer precision)
                    - R.width()/R.height() == width_to_height_ratio (to within integer precision)
                    - center(R) == point(0,0)
        !*/

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

        std::vector<rectangle> create_single_box_detection_template (
            const rectangle& object_box
        );
        /*!
            ensures
                - returns a vector that contains only object_box.
                - In particular, returns a vector V such that:
                    - V.size() == 1
                    - V[0] == object_box
        !*/

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

        std::vector<rectangle> create_overlapped_2x2_detection_template (
            const rectangle& object_box
        );
        /*!
            ensures
                - Divides object_box up into four overlapping regions, the
                  top half, bottom half, left half, and right half.  These
                  four rectangles are returned inside a std::vector.
                - In particular, returns a vector V such that:
                    - V.size() == 4
                    - V[0] == top half of object_box
                    - V[1] == bottom half of object_box
                    - V[2] == left half of object_box
                    - V[3] == right half of object_box
                    - for all valid i: object_box.contains(V[i]) == true
        !*/

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

        std::vector<rectangle> create_grid_detection_template (
            const rectangle& object_box,
            unsigned int cells_x,
            unsigned int cells_y
        );
        /*!
            requires
                - cells_x > 0
                - cells_y > 0
            ensures
                - Divides object_box up into a grid and returns a vector
                  containing all the rectangles corresponding to elements
                  of the grid.  Moreover, the grid will be cells_x elements
                  wide and cells_y elements tall.
                - In particular, returns a vector V such that:
                    - V.size() == cells_x*cells_y
                    - for all valid i:
                        - object_box.contains(V[i]) == true
                        - V[i] == The rectangle corresponding to the ith grid
                          element.
        !*/

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

    }

    #endif // DLIB_DETECTION_TEMPlATE_TOOLS_ABSTRACT_H__