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src/Source/LibJPEG/rdbmp.c  view on Meta::CPAN

    out_ptr = image_ptr[0];
    for (col = source->row_width; col > 0; col--) {
      /* inline copy of read_byte() for speed */
      if ((c = getc(infile)) == EOF)
	ERREXIT(cinfo, JERR_INPUT_EOF);
      *out_ptr++ = (JSAMPLE) c;
    }
  }
  if (progress != NULL)
    progress->completed_extra_passes++;

  /* Set up to read from the virtual array in top-to-bottom order */
  switch (source->bits_per_pixel) {
  case 8:
    source->pub.get_pixel_rows = get_8bit_row;
    break;
  case 24:
    source->pub.get_pixel_rows = get_24bit_row;
    break;
  case 32:
    source->pub.get_pixel_rows = get_32bit_row;
    break;
  default:
    ERREXIT(cinfo, JERR_BMP_BADDEPTH);
  }
  source->source_row = cinfo->image_height;

  /* And read the first row */
  return (*source->pub.get_pixel_rows) (cinfo, sinfo);
}


/*
 * Read the file header; return image size and component count.
 */

METHODDEF(void)
start_input_bmp (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)
{
  bmp_source_ptr source = (bmp_source_ptr) sinfo;
  U_CHAR bmpfileheader[14];
  U_CHAR bmpinfoheader[64];
#define GET_2B(array,offset)  ((unsigned int) UCH(array[offset]) + \
			       (((unsigned int) UCH(array[offset+1])) << 8))
#define GET_4B(array,offset)  ((INT32) UCH(array[offset]) + \
			       (((INT32) UCH(array[offset+1])) << 8) + \
			       (((INT32) UCH(array[offset+2])) << 16) + \
			       (((INT32) UCH(array[offset+3])) << 24))
  INT32 bfOffBits;
  INT32 headerSize;
  INT32 biWidth;
  INT32 biHeight;
  unsigned int biPlanes;
  INT32 biCompression;
  INT32 biXPelsPerMeter,biYPelsPerMeter;
  INT32 biClrUsed = 0;
  int mapentrysize = 0;		/* 0 indicates no colormap */
  INT32 bPad;
  JDIMENSION row_width;

  /* Read and verify the bitmap file header */
  if (! ReadOK(source->pub.input_file, bmpfileheader, 14))
    ERREXIT(cinfo, JERR_INPUT_EOF);
  if (GET_2B(bmpfileheader,0) != 0x4D42) /* 'BM' */
    ERREXIT(cinfo, JERR_BMP_NOT);
  bfOffBits = (INT32) GET_4B(bmpfileheader,10);
  /* We ignore the remaining fileheader fields */

  /* The infoheader might be 12 bytes (OS/2 1.x), 40 bytes (Windows),
   * or 64 bytes (OS/2 2.x).  Check the first 4 bytes to find out which.
   */
  if (! ReadOK(source->pub.input_file, bmpinfoheader, 4))
    ERREXIT(cinfo, JERR_INPUT_EOF);
  headerSize = (INT32) GET_4B(bmpinfoheader,0);
  if (headerSize < 12 || headerSize > 64)
    ERREXIT(cinfo, JERR_BMP_BADHEADER);
  if (! ReadOK(source->pub.input_file, bmpinfoheader+4, headerSize-4))
    ERREXIT(cinfo, JERR_INPUT_EOF);

  switch ((int) headerSize) {
  case 12:
    /* Decode OS/2 1.x header (Microsoft calls this a BITMAPCOREHEADER) */
    biWidth = (INT32) GET_2B(bmpinfoheader,4);
    biHeight = (INT32) GET_2B(bmpinfoheader,6);
    biPlanes = GET_2B(bmpinfoheader,8);
    source->bits_per_pixel = (int) GET_2B(bmpinfoheader,10);

    switch (source->bits_per_pixel) {
    case 8:			/* colormapped image */
      mapentrysize = 3;		/* OS/2 uses RGBTRIPLE colormap */
      TRACEMS2(cinfo, 1, JTRC_BMP_OS2_MAPPED, (int) biWidth, (int) biHeight);
      break;
    case 24:			/* RGB image */
      TRACEMS2(cinfo, 1, JTRC_BMP_OS2, (int) biWidth, (int) biHeight);
      break;
    default:
      ERREXIT(cinfo, JERR_BMP_BADDEPTH);
      break;
    }
    break;
  case 40:
  case 64:
    /* Decode Windows 3.x header (Microsoft calls this a BITMAPINFOHEADER) */
    /* or OS/2 2.x header, which has additional fields that we ignore */
    biWidth = GET_4B(bmpinfoheader,4);
    biHeight = GET_4B(bmpinfoheader,8);
    biPlanes = GET_2B(bmpinfoheader,12);
    source->bits_per_pixel = (int) GET_2B(bmpinfoheader,14);
    biCompression = GET_4B(bmpinfoheader,16);
    biXPelsPerMeter = GET_4B(bmpinfoheader,24);
    biYPelsPerMeter = GET_4B(bmpinfoheader,28);
    biClrUsed = GET_4B(bmpinfoheader,32);
    /* biSizeImage, biClrImportant fields are ignored */

    switch (source->bits_per_pixel) {
    case 8:			/* colormapped image */
      mapentrysize = 4;		/* Windows uses RGBQUAD colormap */
      TRACEMS2(cinfo, 1, JTRC_BMP_MAPPED, (int) biWidth, (int) biHeight);
      break;
    case 24:			/* RGB image */
      TRACEMS2(cinfo, 1, JTRC_BMP, (int) biWidth, (int) biHeight);