libretro-prboom/data/rd_graphic.c

// Copyright (c) 1993-2011 PrBoom developers (see AUTHORS)
// Licence: GPLv2 or later (see COPYING)

// Convert portable pixmap to Doom patch format

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#include "rd_util.h"
#include "rd_palette.h"
#include "rd_graphic.h"

//
// parseppm
//
// try to read a ppm file header and get width/height of image
//

static unsigned char *parseppm(char *ppm, size_t size, const char *file,
                               int *width, int *height)
{
  int maxcol, numpixels;
  char *pos = ppm;

  if (size < 2 || !(*pos++ == 'P' && *pos++ == '6'))
    die("Not a PPM: %s\n", file);

  numpixels  =  *width = strtol(pos, &pos, 0);
  numpixels *= *height = strtol(pos, &pos, 0);
  maxcol = strtol(pos, &pos, 0);

  if (maxcol != 255 || !isspace(*pos++))
    die("Invalid PPM header: %s\n", file);

  if (!numpixels || numpixels > (size-(ppm-pos))/3)
    die("Invalid PPM size: %s\n", file);

  return (unsigned char *)pos;
}

//
// column_pixels_to_colours
//
// make an array of colour indices from a column of raw pixel data
// (random access to which is easier while building a patch column)
//

static void pixels_to_colours(int *colours, unsigned char *pixels,
                              int width, int height, int x)
{
  int i = height;
  int *colour = colours;
  unsigned char *rgb = &pixels[3*x];

  while (--i>=0)
  {
    *colour = palette_getindex(rgb);
    colour++;
    rgb += 3*width;
  }
}

//
// createcolumn
//
// make a doom patch column from an array of colour indices
//

static size_t createcolumn(unsigned char **column, int *colours, int height)
{
  size_t size = 256, length = 0;
  unsigned char *data = xmalloc(size);
  int i, y, top, transparent, opaque;

  for (y = 0; y < height; )
  {
    // we are at the start of a new post
    top = y;

    // count transparent pixels above post and opaque pixels in it
    transparent = opaque = 0;
    for (; y < height && colours[y] == -1; y++) transparent++;
    for (; y < height && colours[y] >= 0; y++) opaque++;

    if (opaque > 0) // this post has pixels
    {
      while (size < length + opaque + 8)
        size *= 2, data = xrealloc(data, size);

      data[length++] = top + transparent; // column offset
      data[length++] = opaque; // length of column
      data[length++] = 0; // padding

      for (i = 0; i < opaque; i++)
        data[length++] = colours[top + transparent + i];

      data[length++] = 0; // more padding
    }
  }
  data[length++] = 0xff; // end of column

  *column = data;
  return length;
}

//
// ppm_to_patch
//
// convert an 8-bit portable pixmap to doom's patch format
// insert_x and insert_y are the graphic/sprite insertion point
//

size_t ppm_to_patch(void **lumpdata, const char *filename,
                    int insert_x, int insert_y)
{
  void *data;
  size_t size = read_or_die(&data, filename);

  int i, width, height, *column_colours;
  unsigned char *pixels, **columns, *patch;
  size_t *columnsizes, totalcolumnsize, offset;

  pixels = parseppm(data, size, filename, &width, &height);
  columns = xmalloc(width * sizeof(*columns));
  columnsizes = xmalloc(width * sizeof(*columnsizes));
  column_colours = xmalloc(height * sizeof(*column_colours));

  for (totalcolumnsize = i = 0; i < width; i++)
  {
    pixels_to_colours(column_colours, pixels, width, height, i);
    columnsizes[i] = createcolumn(&columns[i], column_colours, height);
    totalcolumnsize += columnsizes[i];
  }

  patch = xmalloc(8+4*width+totalcolumnsize);

  ((short *)patch)[0] = SHORT(width);
  ((short *)patch)[1] = SHORT(height);
  ((short *)patch)[2] = SHORT(insert_x);
  ((short *)patch)[3] = SHORT(insert_y);

  for (offset = 8+4*width, i = 0; i < width; i++)
  {
    ((int *)(patch+8))[i] = LONG(offset);
    offset += columnsizes[i];
  }

  for (offset = 8+4*width, i = 0; i < width; i++)
  {
    memmove(patch + offset, columns[i], columnsizes[i]);
    offset += columnsizes[i];
    free(columns[i]);
  }

  free(column_colours);
  free(columnsizes);
  free(columns);
  free(data);

  *lumpdata = patch;
  return 8+4*width+totalcolumnsize;
}