```// Copyright (C) 2011  Davis E. King (davis@dlib.net)
#undef DLIB_DETECTION_TEMPlATE_TOOLS_ABSTRACT_Hh_
#ifdef DLIB_DETECTION_TEMPlATE_TOOLS_ABSTRACT_Hh_

#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_Hh_

```