bmp.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#include "stdafx.h"
#include "random_access_file_type.h"
#include "bmp.h"
#include "core/bitmath_func.hpp"
 
#include "safeguards.h"

static inline bool BmpRead1(RandomAccessFile &file, BmpInfo &info, BmpData &data)
{
  uint8_t pad = GB(4 - info.width / 8, 0, 2);
  for (uint y = info.height; y > 0; y--) {
    uint x = 0;
    uint8_t *pixel_row = &data.bitmap[(y - 1) * static_cast<size_t>(info.width)];
    while (x < info.width) {
      if (file.AtEndOfFile()) return false; // the file is shorter than expected
      uint8_t b = file.ReadByte();
      for (uint i = 8; i > 0; i--) {
        if (x < info.width) *pixel_row++ = GB(b, i - 1, 1);
        x++;
      }
    }
    /* Padding for 32 bit align */
    file.SkipBytes(pad);
  }
  return true;
}

static inline bool BmpRead4(RandomAccessFile &file, BmpInfo &info, BmpData &data)
{
  uint8_t pad = GB(4 - info.width / 2, 0, 2);
  for (uint y = info.height; y > 0; y--) {
    uint x = 0;
    uint8_t *pixel_row = &data.bitmap[(y - 1) * static_cast<size_t>(info.width)];
    while (x < info.width) {
      if (file.AtEndOfFile()) return false;  // the file is shorter than expected
      uint8_t b = file.ReadByte();
      *pixel_row++ = GB(b, 4, 4);
      x++;
      if (x < info.width) {
        *pixel_row++ = GB(b, 0, 4);
        x++;
      }
    }
    /* Padding for 32 bit align */
    file.SkipBytes(pad);
  }
  return true;
}

static inline bool BmpRead4Rle(RandomAccessFile &file, BmpInfo &info, BmpData &data)
{
  uint x = 0;
  uint y = info.height - 1;
  uint8_t *pixel = &data.bitmap[y * static_cast<size_t>(info.width)];
  while (y != 0 || x < info.width) {
    if (file.AtEndOfFile()) return false; // the file is shorter than expected
 
    uint8_t n = file.ReadByte();
    uint8_t c = file.ReadByte();
    if (n == 0) {
      switch (c) {
        case 0: // end of line
          x = 0;
          if (y == 0) return false;
          pixel = &data.bitmap[--y * static_cast<size_t>(info.width)];
          break;
 
        case 1: // end of bitmap
          return true;
 
        case 2: { // delta
          if (file.AtEndOfFile()) return false;
          uint8_t dx = file.ReadByte();
          uint8_t dy = file.ReadByte();
 
          /* Check for over- and underflow. */
          if (x + dx >= info.width || x + dx < x || dy > y) return false;
 
          x += dx;
          y -= dy;
          pixel = &data.bitmap[y * info.width + x];
          break;
        }
 
        default: { // uncompressed
          uint i = 0;
          while (i++ < c) {
            if (file.AtEndOfFile() || x >= info.width) return false;
            uint8_t b = file.ReadByte();
            *pixel++ = GB(b, 4, 4);
            x++;
            if (i++ < c) {
              if (x >= info.width) return false;
              *pixel++ = GB(b, 0, 4);
              x++;
            }
          }
          /* Padding for 16 bit align */
          file.SkipBytes(((c + 1) / 2) % 2);
          break;
        }
      }
    } else {
      /* Apparently it is common to encounter BMPs where the count of
       * pixels to be written is higher than the remaining line width.
       * Ignore the superfluous pixels instead of reporting an error. */
      uint i = 0;
      while (x < info.width && i++ < n) {
        *pixel++ = GB(c, 4, 4);
        x++;
        if (x < info.width && i++ < n) {
          *pixel++ = GB(c, 0, 4);
          x++;
        }
      }
    }
  }
  return true;
}

static inline bool BmpRead8(RandomAccessFile &file, BmpInfo &info, BmpData &data)
{
  uint8_t pad = GB(4 - info.width, 0, 2);
  for (uint y = info.height; y > 0; y--) {
    if (file.AtEndOfFile()) return false; // the file is shorter than expected
    uint8_t *pixel = &data.bitmap[(y - 1) * static_cast<size_t>(info.width)];
    for (uint i = 0; i < info.width; i++) *pixel++ = file.ReadByte();
    /* Padding for 32 bit align */
    file.SkipBytes(pad);
  }
  return true;
}

static inline bool BmpRead8Rle(RandomAccessFile &file, BmpInfo &info, BmpData &data)
{
  uint x = 0;
  uint y = info.height - 1;
  uint8_t *pixel = &data.bitmap[y * static_cast<size_t>(info.width)];
  while (y != 0 || x < info.width) {
    if (file.AtEndOfFile()) return false; // the file is shorter than expected
 
    uint8_t n = file.ReadByte();
    uint8_t c = file.ReadByte();
    if (n == 0) {
      switch (c) {
        case 0: // end of line
          x = 0;
          if (y == 0) return false;
          pixel = &data.bitmap[--y * static_cast<size_t>(info.width)];
          break;
 
        case 1: // end of bitmap
          return true;
 
        case 2: { // delta
          if (file.AtEndOfFile()) return false;
          uint8_t dx = file.ReadByte();
          uint8_t dy = file.ReadByte();
 
          /* Check for over- and underflow. */
          if (x + dx >= info.width || x + dx < x || dy > y) return false;
 
          x += dx;
          y -= dy;
          pixel = &data.bitmap[y * static_cast<size_t>(info.width) + x];
          break;
        }
 
        default: { // uncompressed
          for (uint i = 0; i < c; i++) {
            if (file.AtEndOfFile() || x >= info.width) return false;
            *pixel++ = file.ReadByte();
            x++;
          }
          /* Padding for 16 bit align */
          file.SkipBytes(c % 2);
          break;
        }
      }
    } else {
      /* Apparently it is common to encounter BMPs where the count of
       * pixels to be written is higher than the remaining line width.
       * Ignore the superfluous pixels instead of reporting an error. */
      for (uint i = 0; x < info.width && i < n; i++) {
        *pixel++ = c;
        x++;
      }
    }
  }
  return true;
}

static inline bool BmpRead24(RandomAccessFile &file, BmpInfo &info, BmpData &data)
{
  uint8_t pad = GB(4 - info.width * 3, 0, 2);
  for (uint y = info.height; y > 0; --y) {
    uint8_t *pixel_row = &data.bitmap[(y - 1) * static_cast<size_t>(info.width) * 3];
    for (uint x = 0; x < info.width; ++x) {
      if (file.AtEndOfFile()) return false; // the file is shorter than expected
      *(pixel_row + 2) = file.ReadByte(); // green
      *(pixel_row + 1) = file.ReadByte(); // blue
      *pixel_row       = file.ReadByte(); // red
      pixel_row += 3;
    }
    /* Padding for 32 bit align */
    file.SkipBytes(pad);
  }
  return true;
}

bool BmpReadHeader(RandomAccessFile &file, BmpInfo &info, BmpData &data)
{
  info = {};
 
  /* Reading BMP header */
  if (file.ReadWord() != 0x4D42) return false; // signature should be 'BM'
  file.SkipBytes(8); // skip file size and reserved
  info.offset = file.ReadDword() + file.GetStartPos();
 
  /* Reading info header */
  uint32_t header_size = file.ReadDword();
  if (header_size < 12) return false; // info header should be at least 12 bytes long
 
  info.os2_bmp = (header_size == 12); // OS/2 1.x or windows 2.x info header is 12 bytes long
 
  if (info.os2_bmp) {
    info.width = file.ReadWord();
    info.height = file.ReadWord();
    header_size -= 8;
  } else {
    info.width = file.ReadDword();
    info.height = file.ReadDword();
    header_size -= 12;
  }
 
  if (file.ReadWord() != 1) return false; // BMP can have only 1 plane
 
  info.bpp = file.ReadWord();
  if (info.bpp != 1 && info.bpp != 4 && info.bpp != 8 && info.bpp != 24) {
    /* Only 1 bpp, 4 bpp, 8bpp and 24 bpp bitmaps are supported */
    return false;
  }
 
  /* Reads compression method if available in info header*/
  if ((header_size -= 4) >= 4) {
    info.compression = file.ReadDword();
    header_size -= 4;
  }
 
  /* Only 4-bit and 8-bit rle compression is supported */
  if (info.compression > 2 || (info.compression > 0 && !(info.bpp == 4 || info.bpp == 8))) return false;
 
  if (info.bpp <= 8) {
    /* Reads number of colours if available in info header */
    if (header_size >= 16) {
      file.SkipBytes(12);                  // skip image size and resolution
      info.palette_size = file.ReadDword(); // number of colours in palette
      file.SkipBytes(header_size - 16);    // skip the end of info header
    }
 
    uint maximum_palette_size = 1U << info.bpp;
    if (info.palette_size == 0) info.palette_size = maximum_palette_size;
 
    /* More palette colours than palette indices is not supported. */
    if (info.palette_size > maximum_palette_size) return false;
 
    data.palette.resize(info.palette_size);
 
    for (auto &colour : data.palette) {
      colour.b = file.ReadByte();
      colour.g = file.ReadByte();
      colour.r = file.ReadByte();
      if (!info.os2_bmp) file.SkipBytes(1); // unused
    }
  }
 
  return file.GetPos() <= info.offset;
}

bool BmpReadBitmap(RandomAccessFile &file, BmpInfo &info, BmpData &data)
{
  data.bitmap.resize(static_cast<size_t>(info.width) * info.height * ((info.bpp == 24) ? 3 : 1));
 
  /* Load image */
  file.SeekTo(info.offset, SEEK_SET);
  switch (info.compression) {
    case 0: // no compression
      switch (info.bpp) {
        case 1: return BmpRead1(file, info, data);
        case 4: return BmpRead4(file, info, data);
        case 8: return BmpRead8(file, info, data);
        case 24: return BmpRead24(file, info, data);
        default: NOT_REACHED();
      }
      break;
 
    case 1: return BmpRead8Rle(file, info, data); // 8-bit RLE compression
    case 2: return BmpRead4Rle(file, info, data); // 4-bit RLE compression
    default: NOT_REACHED();
  }
}