GNFT

GRC721-compliant NFT contract for GnoSwap LP positions.

Overview

GNFT represents each liquidity position as a unique NFT with dynamically generated SVG artwork. Each NFT features a gradient background with parameters stored efficiently to minimize gas costs.

Core Features

GRC721 Standard Compliance

• Full implementation of GRC721 interface
• Transfer, approval, and operator management
• Token enumeration and metadata

Dynamic SVG Generation

• Unique gradient backgrounds for each NFT
• Parameters: x1, y1, x2, y2, color1, color2
• On-demand SVG rendering from stored parameters
• Base64-encoded data URI for direct browser display

Gas Optimization

• Compact parameter storage (CSV string format)
• Template-based SVG generation
• Lazy rendering (generate on read, not on mint)
• Minimal storage footprint per token

Integration

• Position contract mints NFTs for new positions
• Staker contract locks NFTs during staking
• Access control via RBAC system
• Halt mechanism for emergency stops

Key Functions

Mint

Mints new NFT for LP position.

Parameters:

• cur realm: Current realm context
• to address: Recipient address
• tid grc721.TokenID: Token ID to mint

Returns: grc721.TokenID

Burn

Burns NFT when position is closed.

Parameters:

• cur realm: Current realm context
• tid grc721.TokenID: Token ID to burn

TransferFrom

Transfers NFT ownership.

Parameters:

• cur realm: Current realm context
• from address: Current owner
• to address: New owner
• tid grc721.TokenID: Token ID to transfer

TokenURI

Returns token metadata with SVG image.

Parameters:

• tid grc721.TokenID: Token ID

Returns: Metadata JSON with base64-encoded SVG

Approve

Approves address to manage specific token.

Parameters:

• cur realm: Current realm context
• to address: Address to approve
• tid grc721.TokenID: Token ID

SetApprovalForAll

Approves operator to manage all tokens.

Parameters:

• cur realm: Current realm context
• operator address: Operator address
• approved bool: Approval status

SVG Generation

Parameter Format

Token URI stores compact parameters:

"x1,y1,x2,y2,#COLOR1,#COLOR2"
Example: "10,12,125,123,#FF5733,#33B5FF"

Parameter Ranges

• x1: 7-13
• y1: 7-13
• x2: 121-126
• y2: 121-126
• colors: 6-digit hex (#RRGGBB)

SVG Structure

1<svg width="135" height="135">
2  <circle cx="67.5" cy="67.5" r="67.5" fill="url(#gradient)"/>
3  <!-- GnoSwap logo paths -->
4  <linearGradient id="gradient" x1="X1" y1="Y1" x2="X2" y2="Y2">
5    <stop stop-color="#COLOR1"/>
6    <stop offset="1" stop-color="#COLOR2"/>
7  </linearGradient>
8</svg>

Rendering Process

1. Mint: Generate random parameters → Store as CSV string
2. TokenURI: Parse CSV → Generate SVG → Encode base64 → Return data URI
3. Display: Browser decodes data URI → Renders SVG

Usage

 1// Position contract mints NFT when creating position
 2import "gno.land/r/gnoswap/gnft"
 3
 4// Mint NFT for new position
 5tokenId := gnft.Mint(cur, ownerAddress, positionId)
 6
 7// Get token metadata with SVG
 8metadata := gnft.TokenURI(tokenId)
 9// Returns: {"name":"Position #1","image":"data:image/svg+xml;base64,..."}
10
11// Transfer NFT
12gnft.TransferFrom(cur, fromAddress, toAddress, tokenId)
13
14// Burn NFT when closing position
15gnft.Burn(cur, tokenId)

Security

• Only position contract can mint NFTs
• Transfers blocked during staking
• RBAC-based access control
• Halt mechanism for emergencies
• Validated parameter ranges
• Secure random generation

Architecture

Dependencies

• gno.land/p/demo/grc/grc721: GRC721 interface
• gno.land/r/gnoswap/rbac: Access control
• gno.land/r/gnoswap/halt: Emergency stops

State Variables

• nft *grc721.AdminToken: GRC721 token instance
• tokenURIs avl.Tree: TokenID → parameter string mapping

Access Control

• owner.AssertOwnedByPrevious(): Only position contract
• checkErr(): Panic on errors
• halt.AssertIsNotHalted*(): Check halt status