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

 */

#if BITS_IN_JSAMPLE != 8
  Sorry, this code only copes with 8-bit JSAMPLEs. /* deliberate syntax err */
#endif

/*
 * Since BMP stores scanlines bottom-to-top, we have to invert the image
 * from JPEG's top-to-bottom order.  To do this, we save the outgoing data
 * in a virtual array during put_pixel_row calls, then actually emit the
 * BMP file during finish_output.  The virtual array contains one JSAMPLE per
 * pixel if the output is grayscale or colormapped, three if it is full color.
 */

/* Private version of data destination object */

typedef struct {
  struct djpeg_dest_struct pub;	/* public fields */

  boolean is_os2;		/* saves the OS2 format request flag */

  jvirt_sarray_ptr whole_image;	/* needed to reverse row order */
  JDIMENSION data_width;	/* JSAMPLEs per row */
  JDIMENSION row_width;		/* physical width of one row in the BMP file */
  int pad_bytes;		/* number of padding bytes needed per row */
  JDIMENSION cur_output_row;	/* next row# to write to virtual array */
} bmp_dest_struct;

typedef bmp_dest_struct * bmp_dest_ptr;


/* Forward declarations */
LOCAL(void) write_colormap
	JPP((j_decompress_ptr cinfo, bmp_dest_ptr dest,
	     int map_colors, int map_entry_size));


/*
 * Write some pixel data.
 * In this module rows_supplied will always be 1.
 */

METHODDEF(void)
put_pixel_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
		JDIMENSION rows_supplied)
/* This version is for writing 24-bit pixels */
{
  bmp_dest_ptr dest = (bmp_dest_ptr) dinfo;
  JSAMPARRAY image_ptr;
  register JSAMPROW inptr, outptr;
  register JDIMENSION col;
  int pad;

  /* Access next row in virtual array */
  image_ptr = (*cinfo->mem->access_virt_sarray)
    ((j_common_ptr) cinfo, dest->whole_image,
     dest->cur_output_row, (JDIMENSION) 1, TRUE);
  dest->cur_output_row++;

  /* Transfer data.  Note destination values must be in BGR order
   * (even though Microsoft's own documents say the opposite).
   */
  inptr = dest->pub.buffer[0];
  outptr = image_ptr[0];
  for (col = cinfo->output_width; col > 0; col--) {
    outptr[2] = *inptr++;	/* can omit GETJSAMPLE() safely */
    outptr[1] = *inptr++;
    outptr[0] = *inptr++;
    outptr += 3;
  }

  /* Zero out the pad bytes. */
  pad = dest->pad_bytes;
  while (--pad >= 0)
    *outptr++ = 0;
}

METHODDEF(void)
put_gray_rows (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo,
	       JDIMENSION rows_supplied)
/* This version is for grayscale OR quantized color output */
{
  bmp_dest_ptr dest = (bmp_dest_ptr) dinfo;
  JSAMPARRAY image_ptr;
  register JSAMPROW inptr, outptr;
  register JDIMENSION col;
  int pad;

  /* Access next row in virtual array */
  image_ptr = (*cinfo->mem->access_virt_sarray)
    ((j_common_ptr) cinfo, dest->whole_image,
     dest->cur_output_row, (JDIMENSION) 1, TRUE);
  dest->cur_output_row++;

  /* Transfer data. */
  inptr = dest->pub.buffer[0];
  outptr = image_ptr[0];
  for (col = cinfo->output_width; col > 0; col--) {
    *outptr++ = *inptr++;	/* can omit GETJSAMPLE() safely */
  }

  /* Zero out the pad bytes. */
  pad = dest->pad_bytes;
  while (--pad >= 0)
    *outptr++ = 0;
}


/*
 * Startup: normally writes the file header.
 * In this module we may as well postpone everything until finish_output.
 */

METHODDEF(void)
start_output_bmp (j_decompress_ptr cinfo, djpeg_dest_ptr dinfo)
{
  /* no work here */
}


/*