Function HandleInvalidSpriteRequest

src/spritecache.cpp:810–844

* Handles the case when a sprite of different type is requested than is present in the SpriteCache. * For SpriteType::Font sprites, it is normal. In other cases, default sprite is loaded instead. * @param sprite ID of loaded sprite * @param requested requested sprite type * @param sc the currently known sprite cache for the requested sprite * @param allocator Callback that provides the memory

 * @note this function will do UserError() in the case the fallback sprite isn't available
 */
static void *HandleInvalidSpriteRequest(SpriteID sprite, SpriteType requested, SpriteCache *sc, SpriteAllocator *allocator, SpriteEncoder *encoder)
{
	static const std::string_view sprite_types[] = {
		"normal",        // SpriteType::Normal
		"map generator", // SpriteType::MapGen
		"character",     // SpriteType::Font
		"recolour",      // SpriteType::Recolour
	};

	SpriteType available = sc->type;
	if (requested == SpriteType::Font && available == SpriteType::Normal) {
		if (sc->ptr == nullptr) sc->type = SpriteType::Font;
		return GetRawSprite(sprite, sc->type, allocator, encoder);
	}

	uint8_t warning_level = sc->warned ? 6 : 0;
	sc->warned = true;
	Debug(sprite, warning_level, "Tried to load {} sprite #{} as a {} sprite. Probable cause: NewGRF interference", sprite_types[static_cast<uint8_t>(available)], sprite, sprite_types[static_cast<uint8_t>(requested)]);

	switch (requested) {
		case SpriteType::Normal:
			if (sprite == SPR_IMG_QUERY) UserError("Uhm, would you be so kind not to load a NewGRF that makes the 'query' sprite a non-normal sprite?");
			[[fallthrough]];
		case SpriteType::Font:
			return GetRawSprite(SPR_IMG_QUERY, SpriteType::Normal, allocator, encoder);
		case SpriteType::Recolour:
			if (sprite == PALETTE_TO_DARK_BLUE) UserError("Uhm, would you be so kind not to load a NewGRF that makes the 'PALETTE_TO_DARK_BLUE' sprite a non-remap sprite?");
			return GetRawSprite(PALETTE_TO_DARK_BLUE, SpriteType::Recolour, allocator, encoder);
		case SpriteType::MapGen:
			/* this shouldn't happen, overriding of SpriteType::MapGen sprites is checked in LoadNextSprite()
			 * (the only case the check fails is when these sprites weren't even loaded...) */
		default:
			NOT_REACHED();
	}
}

/**
 * Reads a sprite (from disk or sprite cache).