import "@thirdweb-dev/contracts/extension/SignatureMintERC721.sol";

The SignatureMintERC721 smart contract is an extension meant for distributing ERC721 tokens.

The 'signature minting' mechanism in the SignatureMintERC721 extension uses EIP-712, and is a way for a contract admin to authorize an external party's request to mint tokens on the admin's contract. At a high level, this means you can authorize some external party to mint tokens on your contract, and specify what exactly will be minted by that external party.

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The SignatureMintERC721 extension is an abstract contract, and expects you to implement the following functions by yourself:

This is an example smart contract demonstrating how to inherit from this extension and override the functions to add (optional) custom functionality.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@thirdweb-dev/contracts/base/ERC721Base.sol";
import "@thirdweb-dev/contracts/extension/SignatureMintERC721.sol";
import "@thirdweb-dev/contracts/lib/CurrencyTransferLib.sol";

contract ERC721SignatureMint is ERC721Base, SignatureMintERC721 {
    constructor(
        address _defaultAdmin,
        string memory _name,
        string memory _symbol,
        address _royaltyRecipient,
        uint128 _royaltyBps
    ) ERC721Base(_defaultAdmin, _name, _symbol, _royaltyRecipient, _royaltyBps) {}

    /// @dev Mints tokens according to the provided mint request.
    function mintWithSignature(
        MintRequest calldata _req,
        bytes calldata _signature
    ) external payable virtual override returns (address signer) {
        require(_req.quantity == 1, "quantity must be 1");

        uint256 tokenIdToMint = nextTokenIdToMint();

        // Verify and process payload.
        signer = _processRequest(_req, _signature);

        address receiver = _req.to;

        // Collect price
        _collectPriceOnClaim(
            _req.primarySaleRecipient,
            _req.quantity,
            _req.currency,
            _req.pricePerToken
        );

        // Mint tokens.
        _setTokenURI(tokenIdToMint, _req.uri);
        _safeMint(receiver, _req.quantity);

        emit TokensMintedWithSignature(signer, receiver, tokenIdToMint, _req);
    }

    /// @dev Returns whether a given address is authorized to sign mint requests.
    function _canSignMintRequest(address _signer)
        internal
        view
        virtual
        override
        returns (bool)
    {
        return _signer == owner();
    }

    /// @dev Collects and distributes the primary sale value of tokens being claimed.
    function _collectPriceOnClaim(
        address _primarySaleRecipient,
        uint256 _quantityToClaim,
        address _currency,
        uint256 _pricePerToken
    ) internal virtual {
        if (_pricePerToken == 0) {
            return;
        }

        uint256 totalPrice = (_quantityToClaim * _pricePerToken) / 1 ether;
        require(totalPrice > 0, "quantity too low");

        if (_currency == CurrencyTransferLib.NATIVE_TOKEN) {
            require(msg.value == totalPrice, "Must send total price.");
        }

        address saleRecipient = _primarySaleRecipient;
        CurrencyTransferLib.transferCurrency(
            _currency,
            msg.sender,
            saleRecipient,
            totalPrice
        );
    }
}

• ERC721SignatureMint