Function ReadRecolourSprite

src/spritecache.cpp:417–444

* Load a recolour sprite into memory. * @param file GRF we're reading from. * @param file_pos Position within file. * @param num Size of the sprite in the GRF. * @param allocator Sprite allocator to use. * @return Sprite data. */

 * @return Sprite data.
 */
static void *ReadRecolourSprite(SpriteFile &file, size_t file_pos, uint num, SpriteAllocator &allocator)
{
	/* "Normal" recolour sprites are ALWAYS 257 bytes. Then there is a small
	 * number of recolour sprites that are 17 bytes that only exist in DOS
	 * GRFs which are the same as 257 byte recolour sprites, but with the last
	 * 240 bytes zeroed.  */
	static const uint RECOLOUR_SPRITE_SIZE = 257;
	uint8_t *dest = allocator.Allocate<uint8_t>(std::max(RECOLOUR_SPRITE_SIZE, num));

	file.SeekTo(file_pos, SEEK_SET);
	if (file.NeedsPaletteRemap()) {
		uint8_t *dest_tmp = new uint8_t[std::max(RECOLOUR_SPRITE_SIZE, num)];

		/* Only a few recolour sprites are less than 257 bytes */
		if (num < RECOLOUR_SPRITE_SIZE) std::fill_n(dest_tmp, RECOLOUR_SPRITE_SIZE, 0);
		file.ReadBlock(dest_tmp, num);

		/* The data of index 0 is never used; "literal 00" according to the (New)GRF specs. */
		for (uint i = 1; i < RECOLOUR_SPRITE_SIZE; i++) {
			dest[i] = _palmap_w2d[dest_tmp[_palmap_d2w[i - 1] + 1]];
		}
		delete[] dest_tmp;
	} else {
		file.ReadBlock(dest, num);
	}

	return dest;
}

/**
 * Read a sprite from disk.