image.h

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/*
Copyright (C) 2006 Pedro Felzenszwalb

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
*/

/* a simple image class */

#pragma once

#include <cstring>

namespace distance_transform
{

  template <class T>
  class image {
   public:
    /* create an image */
    image(const int width, const int height, const bool init = true);

    /* delete an image */
    ~image();

    /* init an image */
    void init(const T &val);

    /* copy an image */
    image<T> *copy() const;
    
    /* get the width of an image. */
    int width() const { return w; }
    
    /* get the height of an image. */
    int height() const { return h; }
    
    /* image data. */
    T *data;
    
    /* row pointers. */
    T **access;
    
   private:
    int w, h;
  };

  /* use imRef to access image data. */
#define imRef(im, x, y) (im->access[y][x])
    
  /* use imPtr to get pointer to image data. */
#define imPtr(im, x, y) &(im->access[y][x])

  template <class T>
  image<T>::image(const int width, const int height, const bool init) {
    w = width;
    h = height;
    data = new T[w * h];  // allocate space for image data
    access = new T*[h];   // allocate space for row pointers
    
    // initialize row pointers
    for (int i = 0; i < h; i++)
      access[i] = data + (i * w);  
    
    if (init)
      memset(data, 0, w * h * sizeof(T));
  }

  template <class T>
  image<T>::~image() {
    delete [] data; 
    delete [] access;
  }

  template <class T>
  void image<T>::init(const T &val) {
    T *ptr = imPtr(this, 0, 0);
    T *end = imPtr(this, w-1, h-1);
    while (ptr <= end)
      *ptr++ = val;
  }

  template <class T>
  image<T> *image<T>::copy() const {
    image<T> *im = new image<T>(w, h, false);
    memcpy(im->data, data, w * h * sizeof(T));
    return im;
  }

} // namespace