src/spriteloader/sprite_file.cpp

   1 /*
   2  * This file is part of OpenTTD.
   3  * 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.
   4  * 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.
   5  * 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 <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file sprite_file.cpp Implementation of logic specific to the SpriteFile class. */
   9
  10 #include "../stdafx.h"
  11 #include "sprite_file_type.hpp"
  12
  13 /** Signature of a container version 2 GRF. */
  14 extern const uint8_t _grf_cont_v2_sig[8] = {'G', 'R', 'F', 0x82, 0x0D, 0x0A, 0x1A, 0x0A};
  15
  16 /**
  17  * Get the container version of the currently opened GRF file.
  18  * @return Container version of the GRF file or 0 if the file is corrupt/no GRF file.
  19  */
  20 static uint8_t GetGRFContainerVersion(SpriteFile &file)
  21 {
  22         size_t pos = file.GetPos();
  23
  24         if (file.ReadWord() == 0) {
  25                 /* Check for GRF container version 2, which is identified by the bytes
  26                  * '47 52 46 82 0D 0A 1A 0A' at the start of the file. */
  27                 for (const auto &expected_sig_byte : _grf_cont_v2_sig) {
  28                         if (file.ReadByte() != expected_sig_byte) return 0; // Invalid format
  29                 }
  30
  31                 return 2;
  32         }
  33
  34         /* Container version 1 has no header, rewind to start. */
  35         file.SeekTo(pos, SEEK_SET);
  36         return 1;
  37 }
  38
  39 /**
  40  * Create the SpriteFile.
  41  * @param filename      Name of the file at the disk.
  42  * @param subdir        The sub directory to search this file in.
  43  * @param palette_remap Whether a palette remap needs to be performed for this file.
  44  */
  45 SpriteFile::SpriteFile(const std::string &filename, Subdirectory subdir, bool palette_remap)
  46         : RandomAccessFile(filename, subdir), palette_remap(palette_remap)
  47 {
  48         this->container_version = GetGRFContainerVersion(*this);
  49         this->content_begin = this->GetPos();
  50 }