writeBMP.hpp

#ifndef UMPIRE_WRITEBMP_H_
#define UMPIRE_WRITEBMP_H_

#include <assert.h>
#include <stdio.h>

static void WriteBMP(int x, int y, unsigned char *bmp, const char * name)
{
  const unsigned char bmphdr[54] = {66, 77, 255, 255, 255, 255, 0, 0, 0, 0, 54, 4, 0, 0, 40, 0, 0, 0, 255, 255, 255, 255, 255, 255, 255, 255, 1, 0, 8, 0, 0, 0, 0, 0, 255, 255, 255, 255, 196, 14, 0, 0, 196, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
  unsigned char hdr[1078];
  int i, j, c, xcorr, diff;
  FILE *f;

  xcorr = (x+3) >> 2 << 2;  // BMPs have to be a multiple of 4 pixels wide.
  diff = xcorr - x;
  for (i = 0; i < 54; i++) hdr[i] = bmphdr[i];
    *((int*)(&hdr[18])) = xcorr;
    *((int*)(&hdr[22])) = y;
    *((int*)(&hdr[34])) = xcorr*y;
    *((int*)(&hdr[2])) = xcorr*y + 1078;
    for (i = 0; i < 256; i++) {
      j = i*4 + 54;
      hdr[j+0] = i;  // blue
      hdr[j+1] = i;  // green
      hdr[j+2] = i;  // red
      hdr[j+3] = 0;  // dummy
    }

    f = fopen(name, "wb");
    assert(f != NULL);
    c = fwrite(hdr, 1, 1078, f);
    assert(c == 1078);
    if (diff == 0) {
      c = fwrite(bmp, 1, x*y, f);
      assert(c == x*y);
    } else {
      *((int*)(&hdr[0])) = 0;  // need up to three zero bytes
      for (j = 0; j < y; j++) {
        c = fwrite(&bmp[j * x], 1, x, f);
  assert(c == x);
  c = fwrite(hdr, 1, diff, f);
  assert(c == diff);
      }
    }
  fclose(f);
}

#endif //UMPIRE_WRITEBMP_H_