/*				*/
/*	画像のファイル入出力	*/
/*				*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "vision.h"

#define	DEBUG	0

/*
  PGM 形式ファイルの読み書き
	pgmFileWrite
	pgmFileRead
*/
  
static char pgmFileHeader[] = "P5 %d %d %d\n";

/*
  配列 data[] : 各画素のピクセル値

	data[0]	    data[1]		... data[WIDTH-1]
	data[WIDTH] data[WIDTH+1]	... data[2WIDTH-1]
	   ...				...   ...
	data[(HEIGHT-1)*WIDTH]		... data[HEIGHT*WIDTH-1]
	
	左上端から，右に進む．
	右端に到達したら，一つ下の行の左端に進む．
	右下端の画素で終了．
*/

extern int pgmFileWrite(FILE *fp, int width, int height, int max, unsigned char *data)
{
  fprintf(fp, pgmFileHeader, width, height, max);
  fwrite(data, sizeof(unsigned char), width*height, fp);
}

extern int pgmFileRead(FILE *fp, int *pwidth, int *pheight, int *pmax, unsigned char *data)
{
  fscanf(fp, pgmFileHeader, pwidth, pheight, pmax);
  fread(data, sizeof(unsigned char), (*pwidth)*(*pheight), fp);
}

#define BUFMAXSIZE	640*640
static unsigned char buf[BUFMAXSIZE];

/*
  画像の入出力
	imageWrite
	imageRead
*/

/*
  画像をファイルに書き出す．
  画像は二次元配列 double image[swidth][sheight] に入っている．
	swidth, sheight : 配列の大きさ
  画像の横幅はwidth，高さはheightである．
  ピクセル値は，
	image[i][j]
		i=woffset, woffset+wstep, ..., woffset+wstep*(width-1)
		j=hoffset, hoffset+hstep, ..., hoffset+hstep*(height-1)
	左下端格子点 [woffset,hoffset]
	横方向:wstep毎 縦方向:hstep毎
  に入っている．

	image[0][HEIGHT-1]      ... image[WIDTH-1][HEIGHT-1]
		...		...	...
	image[0][1] image[1][1] ... image[WIDTH-1][1]
	image[0][0] image[1][0] ... image[WIDTH-1][0]
*/

extern int imageWrite(FILE *fp, int width, int height,
		      int woffset, int hoffset, int wstep, int hstep,
		      int swidth, int sheight, double *image)
{
  int	i, j, k;
  
#if DEBUG
  fprintf(stderr, "imageWrite: width=%d height=%d\n", width, height);
#endif
  
  if (width > swidth || height > sheight) {
    fprintf(stderr, "imageWrite: width %d > size %d or height %d > size %d\n",
	    width, swidth, height, sheight);
    exit(1);
  }
  if (width*height >= BUFMAXSIZE ) {
    fprintf(stderr, "imageWrite: width %d times height %d >= %d >= %d\n",
	    width, height, width*height, BUFMAXSIZE);
    exit(1);
  }
  
  k = 0;
  for (j = hoffset+hstep*(height-1); j >= hoffset; j -= hstep) {
    for (i = woffset; i < woffset+wstep*width; i += wstep) {
      //buf[k++] = image[sheight*i+j];
      buf[k++] = ELEMENT(image,swidth,sheight,i,j);
    }
  }
  
  pgmFileWrite(fp, width, height, PIXELMAXVALUE, buf);
}

/*
  画像をファイルから読み込む．
  画像は二次元配列 double image[swidth][sheight] に入る．
	swidth, sheight : 配列の大きさ
  画像の横幅は *pwidth，高さは *pheight に入る．
  ピクセル値は，
	image[i][j]
		i=woffset, woffset+wstep, ..., woffset+wstep*(width-1)
		j=hoffset, hoffset+hstep, ..., hoffset+hstep*(height-1)
	左端端格子点 [woffset,hoffset] 横方向:wstep毎 縦方向:hstep毎
  に入る．

	image[0][HEIGHT-1]      ... image[WIDTH-1][HEIGHT-1]
		...		...	...
	image[0][1] image[1][1] ... image[WIDTH-1][1]
	image[0][0] image[1][0] ... image[WIDTH-1][0]
*/

extern int imageRead(FILE *fp, int *pwidth, int *pheight,
		     int woffset, int hoffset, int wstep, int hstep,
		     int swidth, int sheight, double *image)
{
  int	i, j, k, max;
  
  pgmFileRead(fp, pwidth, pheight, &max, buf);
  
#if DEBUG
  fprintf(stderr, "imageRead: width=%d height=%d\n", *pwidth, *pheight);
#endif

  if (*pwidth > swidth || *pheight > sheight) {
    fprintf(stderr, "imageRead: width %d > size %d or height %d > size %d\n",
	    *pwidth, swidth, *pheight, sheight);
    exit(1);
  }
  if ((*pwidth)*(*pheight) >= BUFMAXSIZE) {
    fprintf(stderr, "imageRead: width %d times height %d >= %d > %d\n",
	    *pwidth, *pheight, (*pwidth)*(*pheight), BUFMAXSIZE);
    exit(1);
  }
  
  k = 0;
  for (j=(*pheight)-1; j>=0; j--) {
    for (i=0; i<(*pwidth); i++) {
      //image[sheight*i+j] = buf[k++];
      ELEMENT(image,swidth,sheight,i,j)	= buf[k++];
    }
  }
}