QRCoder.Core - QR Code Generator Library

Leia em Portugues (pt-BR)

Documentation

• Usage Guide (English) — PNG, SVG, PDF, ASCII, Base64, Postscript, Artistic QR Codes
• Guia de Uso (Portugues) — PNG, SVG, PDF, ASCII, Base64, Postscript, QR Codes Artisticos

Project Description

QRCoder.Core is a cross-platform .NET library for QR Code generation using SkiaSharp for image rendering. Compatible with Windows, Linux, macOS, and mobile (Xamarin / MAUI).

Based on QRCoder. Developed and maintained by AFONSOFT.

Supported Output Formats

Format	Class	Description
SKBitmap	QRCode	SkiaSharp bitmap image (cross-platform)
PNG	PngByteQRCode	PNG byte array (no System.Drawing needed)
SVG	SvgQRCode	Scalable vector graphics string
PDF	PdfByteQRCode	PDF document as byte array
ASCII	AsciiQRCode	ASCII art for terminal output
Base64	Base64QRCode	Base64-encoded image string
Postscript	PostscriptQRCode	Postscript/EPS format
Artistic	ArtQRCode	Custom QR with rounded dots and backgrounds
BMP Bytes	BitmapByteQRCode	Bitmap byte array

Supported Payload Types

The PayloadGenerator class provides formatted strings for common QR code use cases:

Payload	Description
Url	Website URL
WiFi	Wi-Fi network credentials
Mail	Email with subject and body
SMS	SMS message
PhoneNumber	Phone number
MMS	Multimedia message
Geolocation	GPS coordinates
CalendarEvent	Calendar event (iCal/vEvent)
ContactData	vCard / MeCard contact
BitcoinLikeCryptoCurrencyAddress	Bitcoin/crypto payment
Girocode	European SEPA payment
BezahlCode	German payment standard
SwissQrCode	Swiss QR-bill payment
OneTimePassword	TOTP/HOTP for 2FA
ShadowSocksConfig	ShadowSocks proxy config
Bookmark	Browser bookmark
SkypeCall	Skype call link
WhatsAppMessage	WhatsApp message
RussiaPaymentOrder	Russian payment order
SlovenianUpnQr	Slovenian UPN QR payment

Test Coverage

Metric	Coverage	Status
Line Coverage	96.9%	Excellent
Branch Coverage	92.6%	Excellent
Method Coverage	96.0%	Excellent
Total Tests	502	All Passed

Project Status

Complete - Actively maintained with modern CI/CD pipelines.

Business Vision

QRCoder.Core provides a lightweight, cross-platform foundation for QR code generation that can be embedded in any .NET product — from mobile and web backends to desktop and CLI tooling. The goal is to remove platform-specific graphics dependencies while offering a predictable, extensible API for multiple output formats and industry-standard payloads.

Technical Vision

The library is organized as a Clean Architecture pipeline:

• Generation: QRCodeGenerator builds an abstract QRCodeData matrix (models).
• Payloads: PayloadGenerator formats standard data strings (Wi-Fi, vCard, SEPA, etc.) without coupling to rendering.
• Rendering: AbstractQRCode implementations produce output formats (PNG, SVG, PDF, ASCII, Base64, Postscript, Art, BMP) using SkiaSharp for cross-platform bitmap rendering.
• Dependency rule: Abstractions and Models have no external dependencies; Renderers and Generators depend only on Models and Abstractions.
• Quality gates: build with zero warnings, xUnit tests with ~97% line coverage, and static analysis via SonarCloud / Codecov / Snyk.

Prerequisites

This library is compatible with multiple .NET versions:

• .NET Standard 2.1 — Maximum compatibility
• .NET 8.0 — LTS recommended
• .NET 10.0 — Latest version
• .NET Framework 4.8 — Legacy support

Technologies Used:

• C# — Primary programming language
• SkiaSharp — Cross-platform graphics library for rendering
• SkiaSharp.Views — SkiaSharp UI components
• System.Text.Encoding.CodePages — Additional code page support
• Microsoft.Extensions.ObjectPool — Reusable buffer pooling
• xUnit — Unit testing framework
• Shouldly — Assertion library
• coverlet — Cross-platform code coverage
• dotnet-reportgenerator-globaltool — Coverage report generation
• GitHub Actions — CI/CD automation
• SonarCloud — Static analysis and quality gates
• Codecov — Coverage reporting
• Snyk — Security vulnerability scanning

Installation

NuGet Package Manager (recommended)

Install-Package QRCoder.Core

.NET CLI

dotnet add package QRCoder.Core

PackageReference

<PackageReference Include="QRCoder.Core" Version="2.0.1" />

Quick Start

Generate your first QR code with just a few lines of code:

using System;
using System.IO;
using QRCoder.Core.Generators;
using QRCoder.Core.Models;
using QRCoder.Core.Renderers;
using SkiaSharp;

// Create the QR Code generator
using var generator = new QRCodeGenerator();
using var data = generator.CreateQrCode("https://github.com/afonsoft/QRCoder.Core",
    QRCodeGenerator.ECCLevel.M);

// Render as PNG bytes (cross-platform, no System.Drawing needed)
using var png = new PngByteQRCode(data);
byte[] pngBytes = png.GetGraphic(10);
File.WriteAllBytes("qrcode.png", pngBytes);

// Or render as SKBitmap
using var qrCode = new QRCode(data);
using var bitmap = qrCode.GetGraphic(10);

More Output Formats

using System;
using System.IO;
using QRCoder.Core.Generators;
using QRCoder.Core.Models;
using QRCoder.Core.Renderers;
using SkiaSharp;

// SVG output
using var svg = new SvgQRCode(data);
string svgString = svg.GetGraphic(10);

// ASCII output (great for terminal)
using var ascii = new AsciiQRCode(data);
Console.WriteLine(ascii.GetGraphic(1));

// PDF output
using var pdf = new PdfByteQRCode(data);
byte[] pdfBytes = pdf.GetGraphic(5);

// Base64 PNG (embed in HTML)
using var b64 = new Base64QRCode(data);
string base64Img = b64.GetGraphic(10);
// Use in HTML: <img src="data:image/png;base64,{base64Img}" />

// With custom colors
using var colorQr = new QRCode(data);
using var colorBmp = colorQr.GetGraphic(10, "#1a1a2e", "#e0e0e0");

// Postscript / EPS
using var ps = new PostscriptQRCode(data);
string psString = ps.GetGraphic(5);

Payload Examples

using System;
using System.IO;
using QRCoder.Core.Generators;
using QRCoder.Core.Models;
using QRCoder.Core.Renderers;
using SkiaSharp;

// Wi-Fi QR Code
var wifiPayload = new PayloadGenerator.WiFi("MyNetwork", "MyPassword",
    PayloadGenerator.WiFi.Authentication.WPA);
using var gen = new QRCodeGenerator();
using var wifiData = gen.CreateQrCode(wifiPayload.ToString(), QRCodeGenerator.ECCLevel.M);

// URL QR Code
var urlPayload = new PayloadGenerator.Url("https://github.com/afonsoft/QRCoder.Core");
using var urlData = gen.CreateQrCode(urlPayload.ToString(), QRCodeGenerator.ECCLevel.M);

// Email QR Code
var mailPayload = new PayloadGenerator.Mail("[email protected]", "Subject", "Body text");
using var mailData = gen.CreateQrCode(mailPayload.ToString(), QRCodeGenerator.ECCLevel.M);

// Phone Number
var phonePayload = new PayloadGenerator.PhoneNumber("+5511999999999");
using var phoneData = gen.CreateQrCode(phonePayload.ToString(), QRCodeGenerator.ECCLevel.M);

// Contact Card (vCard)
var contactPayload = new PayloadGenerator.ContactData(
    PayloadGenerator.ContactData.ContactOutputType.VCard3,
    "Doe", "John",
    phone: "+5511999999999",
    email: "[email protected]");
using var contactData = gen.CreateQrCode(contactPayload.ToString(), QRCodeGenerator.ECCLevel.M);

See the full Usage Guide for all output formats, payload types, advanced settings, and error correction levels.

Error Correction Levels

Level	Recovery	Use Case
ECCLevel.L	~7%	Maximum data capacity
ECCLevel.M	~15%	General purpose (recommended)
ECCLevel.Q	~25%	Higher reliability
ECCLevel.H	~30%	Maximum error recovery (logos, artistic QR)

Repository Structure

.
├── QRCoder.Core/              # Core library source code
│   ├── Abstractions/          # Abstract base class and contracts
│   │   └── AbstractQRCode.cs  # Base class for all renderers
│   ├── Models/                # QR code data model and value objects
│   │   ├── QRCodeData.cs      # QR code data structure
│   │   └── Size.cs            # Rendering size value object
│   ├── Generators/            # QR code generation engine
│   │   ├── QRCodeGenerator.cs # Main QR code data generator
│   │   └── PayloadGenerator.cs# Payload formatters (WiFi, URL, etc.)
│   ├── Renderers/             # Output format renderers
│   │   ├── QRCode.cs          # SKBitmap renderer
│   │   ├── PngByteQRCode.cs   # PNG byte array renderer
│   │   ├── SvgQRCode.cs       # SVG string renderer
│   │   ├── PdfByteQRCode.cs   # PDF byte array renderer
│   │   ├── AsciiQRCode.cs     # ASCII art renderer
│   │   ├── Base64QRCode.cs    # Base64 image renderer
│   │   ├── PostscriptQRCode.cs# Postscript/EPS renderer
│   │   ├── ArtQRCode.cs       # Artistic QR code renderer
│   │   └── BitmapByteQRCode.cs# BMP byte array renderer
│   ├── Extensions/            # SkiaSharp and helper extensions
│   ├── Exceptions/            # Custom exceptions
│   └── Assets/                # NuGet assets
├── QRCoder.Core.Tests/        # Unit tests (502 tests)
├── QRCoder.Core.Benchmarks/   # Performance benchmarks
├── docs/                      # Usage guides
│   ├── en-US/usage-guide.md   # English usage guide
│   └── pt-BR/guia-de-uso.md   # Portuguese usage guide
├── .github/workflows/         # CI/CD pipelines
├── CHANGELOG.md               # Version history
└── README.md / README.pt-br.md# English and Portuguese documentation

CI/CD and Build

This project uses a complete CI/CD pipeline with GitHub Actions:

Available Workflows

• Build & Pack — Main build with tests, coverage, and package creation
• Code Quality — Code analysis with Qodana and SonarCloud
• Security Scans — Security analysis with CodeQL, Snyk, and SonarCloud
• Publish NuGet — Automatic publishing to NuGet.org and GitHub Packages
• CI Build & Test — Continuous build and automated testing

Running Tests Locally

# Build the project
dotnet build QRCoder.Core.sln --configuration Release

# Run all tests with coverage
dotnet test QRCoder.Core.Tests/QRCoder.Core.Tests.csproj \
  --configuration Release \
  --logger "trx;LogFileName=test-results.trx" \
  --results-directory TestResults \
  --collect:"XPlat Code Coverage"

# Generate HTML coverage report
dotnet tool install -g dotnet-reportgenerator-globaltool
reportgenerator \
  -reports:"TestResults/**/coverage.cobertura.xml" \
  -targetdir:"TestResults/CoverageReport" \
  -reporttypes:"Html;XmlSummary;TextSummary"

# View report: open TestResults/CoverageReport/index.html

Contributing

1. Create a branch from main:

   git checkout -b feature/your-feature

2. Make your changes following code conventions

3. Automated workflows will run:

   • Build & Pack — Validates your code
   • Code Quality — Analyzes quality
   • Security Scan — Checks security

4. Pull Request: Create a PR to main

5. Review and Merge: After approval, your code will be merged

Developers

• Afonso Dutra Nogueira Filho (AFONSOFT) — Lead developer

Star History

StarMapper

License

This project is licensed under the MIT License. See the LICENSE.txt file for details.

Changelog

See the full CHANGELOG.md for the complete version history.

[2.0.1] - 2026-07-11

Added

• XML documentation for all public APIs (CS1591 removed from NoWarn).
• Repository structure, business vision, and technical vision sections in README.
• BDDTests.cs with BDD-style Given/When/Then tests for QR code generation and rendering.

Changed

• Bumped package version to 2.0.1.
• Updated CI, NuGet, SonarCloud, and Codecov badges in README files.
• Updated SonarCloud links to the correct project (afonsoft_QRCoder.Core).
• Consolidated CHANGELOG.md following Keep a Changelog and SemVer.

Fixed

• Broken NuGet badge (now using shields.io).
• Broken CI build badge (now using ci-build-test.yml).
• SonarQube S2184 (integer division in PdfByteQRCode media size).
• SonarQube S4136 by grouping GetGraphic overloads in QRCode and PdfByteQRCode.

[2.0.0] - 2026-05-10

Changed

• Reorganized codebase with SOLID and Clean Architecture folder structure.
• Multi-language documentation (en-US default + pt-BR).
• Updated target frameworks: .NET Standard 2.1, .NET 8.0, .NET 10.0, .NET Framework 4.8.

[1.0.8] - 2026-02-18

Added

• SkiaSharp native library handling for Linux CI.
• Consolidated publish workflows.

[1.0.5] - 2025-07-13

Changed

• Migrated rendering to SkiaSharp.
• General project and documentation adjustments.

[1.0.3] - 2024-04-01

Changed

• Dependency updates.

Fixed

• Action corrections.