The wallpaper and baseplate objects are designed to prevent multiple deposits in a map contract in order to save on gas fees. You can see behavior of Baseplate from changeWallpaper method.
/*
* @title checkBasePlate
* @notice Functions for check BasePlate status
* @param name : ens name
* @dev Check BasePlate information
* @return contractAddress,tokenId
*/
function checkBasePlate(string memory name) external view returns (BasePlate memory) {
return basePlate[name];
}
/*
* @title changeBasePlate
* @notice Receive changeBasePlate
* @param name : ens name
* @param contractAddress : Address of BasePlate
* @param tokenId : tokenId
*/
function _changeBasePlate(
string memory name,
address contractAddress,
uint256 tokenId
) internal {
address lastBasePlateContractAddress = basePlate[name].contractAddress;
uint256 lastBasePlateTokenId = basePlate[name].tokenId;
// Withdraw the deposited BasePlate OBJECT at the same time if it has already been deposited
if (lastBasePlateContractAddress != address(0)) {
IObject _lastBasePlate = IObject(lastBasePlateContractAddress);
_lastBasePlate.safeTransferFrom(address(this), msg.sender, lastBasePlateTokenId, 1, "0x00");
}
// Check condition
_checkConditon(name, contractAddress, tokenId);
basePlate[name] = BasePlate(contractAddress, tokenId);
// Deposit BasePlate object to be set in map contract
IObject _object = IObject(contractAddress);
_object.safeTransferFrom(msg.sender, address(this), tokenId, 1, "0x00");
emit ChangeBasePlate(name, contractAddress, tokenId);
}
function _checkConditon(
string memory name,
address contractAddress,
uint256 tokenId
) internal view {
// Check that contractAddress is whitelisted.
if (!_whitelist[contractAddress]) revert InvalidWhitelist();
IObject _object = IObject(contractAddress);
IObject.Size memory size = _object.getSize(tokenId);
// Check that the size of the wall object matches the size of the current map contract
if ((size.x != mapSettings.maxX) || (size.y != mapSettings.maxY)) {
revert NotFit(msg.sender, size.x, size.y, mapSettings.maxX, mapSettings.maxY);
}
// Check if user has a wall object
uint256 userBalance = _object.balanceOf(msg.sender, tokenId);
if (userBalance < 1) {
revert NotBalance({ name: name, sender: msg.sender, contractAddress: contractAddress, tokenId: tokenId });
}
}
CheckConditon methods check whether the owner has a baseplate or not, and whether the map size is 8*8 and the baseplate size is consistent.
