[ERC2569] オンチェーン上にSVG画像を保存する仕組みを理解しよう！

// ----- IERC721GetImageSvg.sol -------------------------

pragma solidity ^0.5.0;

import "@openzeppelin/contracts/token/ERC721/IERC721.sol";

/**
 * @title ERC-721 Non-Fungible Token Standard, optional retrieving SVG image extension
 * @dev See https://eips.ethereum.org/EIPS/eip-721
 */
contract IERC721GetImageSvg is IERC721 {
    function getTokenImageSvg(uint256 tokenId) external view returns (string memory);
}


// ----- ERC721GetImageSvg.sol -------------------------

pragma solidity ^0.5.0;

import "@openzeppelin/contracts/GSN/Context.sol";
import "@openzeppelin/contracts/token/ERC721/./ERC721.sol";
import "@openzeppelin/contracts/introspection/ERC165.sol";
import "./IERC721GetImageSvg.sol";

contract ERC721GetImageSvg is Context, ERC165, ERC721, IERC721GetImageSvg {
    // Mapping for token Images
    mapping(uint256 => string) private _tokenImageSvgs;

    /*
     *     bytes4(keccak256('getTokenImageSvg(uint256)')) == 0x87d2f48c
     *
     *     => 0x87d2f48c == 0x87d2f48c
     */
    bytes4 private constant _INTERFACE_ID_ERC721_GET_TOKEN_IMAGE_SVG = 0x87d2f48c;

    /**
     * @dev Constructor function
     */
    constructor () public {
        // register the supported interfaces to conform to ERC721 via ERC165
        _registerInterface(_INTERFACE_ID_ERC721_GET_TOKEN_IMAGE_SVG);
    }

    /**
     * @dev Returns an SVG Image for a given token ID.
     * Throws if the token ID does not exist. May return an empty string.
     * @param tokenId uint256 ID of the token to query
     */
    function getTokenImageSvg(uint256 tokenId) external view returns (string memory) {
        require(_exists(tokenId), "ERC721GetImageSvg: SVG Image query for nonexistent token");
        return _tokenImageSvgs[tokenId];
    }

    /**
     * @dev Internal function to set the token SVG image for a given token.
     * Reverts if the token ID does not exist.
     * @param tokenId uint256 ID of the token to set its SVG image
     * @param imagesvg string SVG  to assign
     */
    function setTokenImageSvg(uint256 tokenId, string memory imagesvg) internal {
        require(_exists(tokenId), "ERC721GetImageSvg: SVG image set of nonexistent token");
        _tokenImageSvgs[tokenId] = imagesvg;
    }

}


// ----- ERC721ImageSvgMintable.sol -------------------------

pragma solidity ^0.5.0;

import "@openzeppelin/contracts/token/ERC721/ERC721Metadata.sol";
import "@openzeppelin/contracts/access/roles/MinterRole.sol";
import "./ERC721GetImageSvg.sol";

/**
 * @title ERC721ImageSvgMintable
 * @dev ERC721 minting logic with imagesvg.
 */
contract ERC721ImageSvgMintable is ERC721, ERC721Metadata, ERC721GetImageSvg, MinterRole {
    /**
     * @dev Function to mint tokens.
     * @param to The address that will receive the minted tokens.
     * @param tokenId The token id to mint.
     * @param tokenImageSvg The token SVG image of the minted token.
     * @return A boolean that indicates if the operation was successful.
     */
    function mintWithTokenImageSvg(address to, uint256 tokenId, string memory tokenImageSvg) public onlyMinter returns (bool) {
        _mint(to, tokenId);
        setTokenImageSvg(tokenId, tokenImageSvg);
        return true;
    }
}


We propose to add three sol files in the existing ERC-1155 implementation.
Here are the details for the proposed sol files.

// ----- IERC1155GetImageSvg.sol -------------------------

pragma solidity ^0.5.0;

import "./IERC1155.sol";

/**
 * @title ERC-1155 Multi Token Standard, retrieving SVG image for a token
 * @dev See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-1155.md
 */
contract IERC1155GetImageSvg is IERC1155 {
    function getTokenImageSvg(uint256 tokenId) external view returns (string memory);
}


// ----- ERC1155GetImageSvg.sol -------------------------

pragma solidity ^0.5.0;

import "./ERC1155.sol";
import "./IERC1155GetImageSvg.sol";

contract ERC1155GetImageSvg is ERC165, ERC1155, IERC1155GetImageSvg {
    // Mapping for token Images
    mapping(uint256 => string) private _tokenImageSvgs;

    /*
     *     bytes4(keccak256('getTokenImageSvg(uint256)')) == 0x87d2f48c
     *
     *     => 0x87d2f48c == 0x87d2f48c
     */
    bytes4 private constant _INTERFACE_ID_ERC1155_GET_TOKEN_IMAGE_SVG = 0x87d2f48c;

    /**
     * @dev Constructor function
     */
    constructor () public {
        // register the supported interfaces to conform to ERC1155 via ERC165
        _registerInterface(_INTERFACE_ID_ERC1155_GET_TOKEN_IMAGE_SVG);
    }


    /**
     * @dev Returns an SVG Image for a given token ID.
     * Throws if the token ID does not exist. May return an empty string.
     * @param tokenId uint256 ID of the token to query
     */
    function getTokenImageSvg(uint256 tokenId) external view returns (string memory) {
        require(_exists(tokenId), "ERC1155GetImageSvg: SVG Image query for nonexistent token");
        return _tokenImageSvgs[tokenId];
    }

    /**
     * @dev Internal function to set the token SVG image for a given token.
     * Reverts if the token ID does not exist.
     * @param tokenId uint256 ID of the token to set its SVG image
     * @param imagesvg string SVG  to assign
     */
    function setTokenImageSvg(uint256 tokenId, string memory imagesvg) internal {
        require(_exists(tokenId), "ERC1155GetImageSvg: SVG image set of nonexistent token");
        _tokenImageSvgs[tokenId] = imagesvg;
    }

}



// ----- ERC1155MixedFungibleWithSvgMintable.sol -------------------------

pragma solidity ^0.5.0;

import "./ERC1155MixedFungibleMintable.sol";
import "./ERC1155GetImageSvg.sol";

/**
    @dev Mintable form of ERC1155 with SVG images
    Shows how easy it is to mint new items with SVG images
*/

contract ERC1155MixedFungibleWithSvgMintable is ERC1155, ERC1155MixedFungibleMintable, ERC1155GetImageSvg {
    /**
     * @dev Function to mint non-fungible tokens.
     * @param _to The address that will receive the minted tokens.
     * @param _type The token type to mint.
     * @param tokenImageSvg The token SVG image of the minted token.
     */
    function mintNonFungibleWithImageSvg(uint256 _type, address[] calldata _to, string memory tokenImageSvg) external creatorOnly(_type) {
        mintNonFungible(_type, _to);
        setTokenImageSvg(_type, tokenImageSvg);
    }


    /**
     * @dev Function to mint fungible tokens.
     * @param _to The address that will receive the minted tokens.
     * @param _id The token type to mint.
     * @param _quantities The number of tokens for a type to mint.
     * @param tokenImageSvg The token SVG image of the minted token.
     */
    function mintFungibleWithImageSvg(uint256 _id, address[] calldata _to, uint256[] calldata _quantities, string memory tokenImageSvg) external creatorOnly(_id) {
        mintFungible(_id, _to, _quantities, tokenImageSvg)  {
        setTokenImageSvg(_id, tokenImageSvg);
    }
}



We propose to add three sol files in the existing ERC-20 implementation.
Here are the details for the proposed sol files.


// ----- IERC20GetImageSvg.sol -------------------------

pragma solidity ^0.5.0;
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";

/**
 * @title ERC-20 Fungible Token Standard, retrieving SVG image for a token
 * @dev See https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol
 */
contract IERC20GetImageSvg is IERC20 {
    function getTokenImageSvg() external view returns (string memory);
}


// ----- ERC20GetImageSvg.sol -------------------------

pragma solidity ^0.5.0;
import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "./IERC20GetImageSvg.sol";

contract ERC20GetImageSvg is ERC20, IERC20GetImageSvg {
    string private _tokenImageSvg;
//将图片实现写在构造器中
    constructor(string calldata svgCode) public {
_tokenImageSvg = svgCode
}

    /**
     * @dev Returns an SVG Image.
     */
    function getTokenImageSvg() external view returns (string memory) {
        return _tokenImageSvg;
    }

}