SkiaSharp.QrCode 0.9.0

SkiaSharp.QrCode

SkiaSharp.QrCode provides high-performance QR code generation with SkiaSharp integration.

Benchmark results comparing SkiaSharp.QrCode with other libraries. See samples/Benchmark for details.

Many existing QR code libraries rely on System.Drawing, which has well-known GDI+ limitations and cross-platform issues. SkiaSharp.QrCode was created to provide high performance, minimum memory allocation, a simpler and more intuitive API while leveraging SkiaSharp's cross-platform capabilities. Generate a QR code in a single line, or customize every detail - the choice is yours.

You can create professional-looking QR codes like this with just a few lines of code:

<p float="left"> <img src="samples/ConsoleApp/samples/pattern14_instagram_frame.png" width="250" alt="Instagram-style"/> <img src="samples/ConsoleApp/samples/pattern6_builder_gradient.png" width="250" alt="Gradient QR"/> <img src="samples/ConsoleApp/samples/pattern7_builder_icon.png" width="250" alt="Icon QR"/> </p>

Overview

SkiaSharp.QrCode is a modern, high-performance QR code generation library built on SkiaSharp. SkiaSharp.QrCode allocates memory only for the actual QR code data, with zero additional allocations during processing.

• Simple API: One-liner QR code generation with sensible defaults
• High Performance: Optimal speed and minimum memory allocation
• Highly Customizable: Gradients, icons, custom shapes, colors, and more
• Cross-Platform: Windows, Linux, macOS, iOS, Android, WebAssembly
• Zero Dependencies: QR generation without external libraries (SkiaSharp for rendering only)
• No System.Drawing: Avoids GDI+ issues and Windows dependencies
• NativeAOT Ready: Full support for .NET Native AOT compilation
• Modern .NET: .NET Standard 2.0, 2.1, .NET 8+

Installation

Visit SkiaSharp.QrCode on NuGet.org

dotnet add package SkiaSharp.QrCode

Quick Start

Simplest Example

Single line QR code generation:

using SkiaSharp.QrCode.Image;

// one-liner save to file
QRCodeImageBuilder.SavePng("Hello", "qrcode.png");

// Or get bytes
var pngBytes = QRCodeImageBuilder.GetPngBytes("https://example.com");

Save Directly to Stream

using SkiaSharp.QrCode.Image;

using var stream = File.OpenWrite("qrcode.png");
QRCodeImageBuilder.SavePng("Your content here", stream, ECCLevel.M, size: 512);

Migration from 0.8.0 to 0.9.0

[TBD]

API Overview

SkiaSharp.QrCode provides three main APIs for different use cases.

Recommendation: Start with QRCodeImageBuilder for most scenarios. Use QRCodeRenderer when you need canvas control. Use QRCodeGenerator only for custom rendering implementations.

QRCodeImageBuilder (Recommended)

Best for Most use cases - simple to advanced QR code generation. The high-level, fluent API for generating QR codes with minimal code. Provides a builder pattern with sensible defaults and extensive customization options.

Key Features:

• One-liner generation with GetPngBytes(), SavePng()
• Fluent API with WithXxx() methods
• Built-in support for colors, gradients, icons, shapes
• Multiple output formats (PNG, JPEG, WebP)
• Stream and byte array output

When to use:

• Quick QR code generation
• Standard customization needs
• File or stream output

Example:

var pngBytes = QRCodeImageBuilder.GetPngBytes("content");

QRCodeRenderer (Advanced)

Best for Custom rendering with full control over the canvas. The mid-level API that renders QR data onto an existing SkiaSharp canvas. Useful when you need to integrate QR codes into existing graphics or add custom post-processing.

Key Features:

• Render to existing SKCanvas
• Full control over rendering area (SKRect)
• Combine with other SkiaSharp drawing operations
• Custom effects and post-processing

When to use:

• Integrating QR codes into existing graphics
• Adding custom decorations or effects
• Multiple elements on the same canvas

Example:

var qrData = QRCodeGenerator.CreateQrCode("content", ECCLevel.M);
var canvas = surface.Canvas;
QRCodeRenderer.Render(canvas, area, qrData, SKColors.Black, SKColors.White);

QRCodeGenerator (Low-Level)

Best for QR data generation without rendering. The low-level API that generates raw QR code data (QRCodeData). Use this when you need the QR data structure itself, not the image.

Key Features:

• Generates QRCodeData (boolean module matrix stored as 1D byte array)
• Specify ECC level, ECI mode, quiet zone size
• No rendering logic included
• Smallest API surface

When to use:

• Custom rendering implementations
• Non-image output (e.g., ASCII art, LED displays)
• Maximum control over the rendering process

Example:

var qrData = QRCodeGenerator.CreateQrCode("content", ECCLevel.M, quietZoneSize: 4);
// Use qrData for custom rendering
// Access individual modules: bool isDark = qrData[row, col];

Platform-Specific Considerations

Linux Support

SkiaSharp requires native dependencies on Linux. You have two options:

Option 1: With Font Support (Recommended for text rendering)

Requires libfontconfig1:

sudo apt update && apt install -y libfontconfig1

<PackageReference Include="SkiaSharp.QrCode" Version="0.9.0" />
<PackageReference Include="SkiaSharp.NativeAssets.Linux" Version="3.119.1" />

Option 2: No Dependencies (QR code only)

If you don't need advanced font operations:

<PackageReference Include="SkiaSharp.QrCode" Version="0.9.0" />
<PackageReference Include="SkiaSharp.NativeAssets.Linux.NoDependencies" Version="3.119.1" />

Note: NoDependencies can still draw text but cannot search fonts based on characters or use system fonts.

See: SkiaSharp Issue #964

NativeAOT Support

SkiaSharp.QrCode fully supports .NET NativeAOT. You need to include platform-specific native assets:

<PropertyGroup>
  <PublishAot>true</PublishAot>
  <PublishTrimmed>true</PublishTrimmed>
  <InvariantGlobalization>true</InvariantGlobalization>
</PropertyGroup>

Windows

<PackageReference Include="SkiaSharp.QrCode" Version="0.9.0" />
<PackageReference Include="SkiaSharp.NativeAssets.Win32" Version="3.119.1" />

Linux

<PackageReference Include="SkiaSharp.QrCode" Version="0.9.0" />
<PackageReference Include="SkiaSharp.NativeAssets.Linux.NoDependencies" Version="3.119.1" />

macOS

<PackageReference Include="SkiaSharp.QrCode" Version="0.9.0" />
<PackageReference Include="SkiaSharp.NativeAssets.macOS" Version="3.119.1" />

Performance

SkiaSharp.QrCode is designed with performance as a top priority. The library minimizes memory allocations and maximizes throughput for QR code generation.

Key Performance Characteristics

• Minimal Memory Allocation: Memory is only allocated for the final QR code data structure. The generation algorithm avoids intermediate allocations, resulting in minimal GC pressure.
• Zero-Copy Rendering: Direct rendering to SkiaSharp canvas without unnecessary buffer copies.
• Optimized Encoding: Efficient encoding mode selection and bit packing minimize QR code size and generation time.
• Native Performance: Leverages SkiaSharp's native rendering engine for maximum speed.

Benchmark Results

Benchmark results show SkiaSharp.QrCode outperforming other popular .NET QR code libraries in both speed and memory usage.

• Fastest Generation: Outperforms other .NET QR code libraries in most scenarios
• Lowest Memory Usage: Minimal allocations reduce GC overhead
• Consistent Performance: Predictable performance across different QR code sizes and complexity

For detailed benchmark code and results, see the samples/Benchmark directory.

FAQ

Why choose SkiaSharp.QrCode?

SkiaSharp offers several advantages for QR code generation:

• Performance: Native-level performance with hardware acceleration support
• Cross-Platform: Runs on Windows, Linux, macOS, iOS, Android, and WebAssembly
• Modern .NET Support: First-class support for .NET 6+ and .NET Core
• No GDI+ Dependencies: Avoids System.Drawing's Windows-specific issues
• Rich Graphics API: Advanced rendering capabilities (gradients, shapes, effects)
• Active Development: Well-maintained with regular updates

Can I use this in ASP.NET Core?

Yes, SkiaSharp.QrCode works great in ASP.NET Core. SkiaSharp.QrCode also supports IBufferWriter for efficient memory usage.

app.MapGet("/qr", (string url) =>
{
    var pngBytes = QRCodeImageBuilder.GetPngBytes(url);
    return Results.File(pngBytes, "image/png");
});

Does it support Blazor WebAssembly?

Yes, SkiaSharp works in Blazor WebAssembly. See the samples/BlazorWasm folder for a complete example.

What about NativeAOT and trimming?

Yes, fully supported. See the Platform-Specific Considerations section for details on required native assets.

ISO-8859-2 and other encodings supports

Currently, SkiaSharp.QrCode supports ISO-8859-1 and UTF-8. Other encodings (e.g., ISO-8859-2, Shift JIS) are not supported at this time. This is mainly due to almost all QR code use cases being UTF-8 compatible nowadays. ISO-8859-2 and other legacy encodings are rarely used in practice.

Any plan to support QR code scanning?

Currently, SkiaSharp.QrCode focuses on QR code generation. QR code scanning is not planned at this time, but contributions are welcome.

What QR code style provides the best scan reliability?

For optimal scan reliability, we recommend:

• Use rectangular modules (default): Rectangle-shaped modules (RectangleModuleShape) provide the lowest error rate when scanning QR codes.
• Avoid gaps between modules: Using smaller module sizes or shapes like Circle or RoundRect creates gaps between modules, which increases scan error rates.
• Use ECCLevel.H for non-standard styles: If you need to use Circle, RoundRect, or other custom module shapes, we strongly recommend setting the error correction level to ECCLevel.H (High - 30% recovery capacity) to compensate for the reduced readability.
• Always use ECCLevel.H with icons/logos: When embedding icons or logos using IconData, ECCLevel.H is required to ensure the QR code remains scannable even when the center is partially obscured.

Example:

// Best reliability - default settings with rectangular modules
var pngBytes = QRCodeImageBuilder.GetPngBytes("https://example.com");

// If using Circle or RoundRect - use High error correction
var qrCode = new QRCodeImageBuilder("https://example.com")
    .WithSize(800, 800)
    .WithErrorCorrection(ECCLevel.H) // Required for custom shapes
    .WithModuleShape(CircleModuleShape.Default);

// When using icons/logos - always use High error correction
using var logo = SKBitmap.Decode("logo.png");
var icon = new IconData { Icon = logo, IconSizePercent = 15 };

var qrCodeWithIcon = new QRCodeImageBuilder("https://example.com")
    .WithSize(800, 800)
    .WithErrorCorrection(ECCLevel.H) // Required for icons
    .WithIcon(icon);

How can I display QR codes in LINQPad?

Following shows how to display a QRCode inside a LINQPad Results pane.

Bitmap.FromStream(new MemoryStream(QRCodeImageBuilder.GetPngBytes("WIFI:T:WPA;S:mynetwork;P:mypass;;"));

QR code Specifications

ECC Level (Error Correction Levels)

QR codes support four levels of error correction, which allow the code to remain readable even when partially damaged or obscured:

Tip: Use ECC Level H when embedding icons in QR codes to ensure readability even when the center is obscured.

Encoding Modes

QR codes support different encoding modes optimized for specific character types:

Note: The library automatically selects the most efficient encoding mode for your content.

Version and Size

QR codes come in 40 versions (sizes), from Version 1 (21×21 modules) to Version 40 (177×177 modules). Each version adds 4 modules per side.

• Version 1: 21×21 modules
• Version 2: 25×25 modules
• ...
• Version 40: 177×177 modules

The library automatically selects the minimum version that can fit your content based on the selected ECC level.

Data Capacity Reference

The actual capacity depends on the encoding mode, ECC level, and version. Below are practical capacities including overhead (based on test data using 'あ' for UTF-8 multi-byte characters):

Quick Reference (Version 10, Common Use Cases)

UTF-8 multi-byte: Japanese hiragana 'あ' (3 bytes/char). For ASCII text (1 byte/char), the capacity is approximately 3× the values shown.

Full capacity tables for all versions (1-40) and ECC levels are available in the Data Capacity Tables section below.

Data Capacity Tables

Full capacity tables for all QR code versions and ECC Levels.

Test Characters:

• Numeric: '1' (digit)
• Alphanumeric: 'A' (uppercase letter)
• Byte (ASCII): 'a' (lowercase, 1 byte)
• Byte (UTF-8): 'あ' (hiragana, 3 bytes)

Important Notes:

• Numeric: Pure digit count (0-9)
• Alphanumeric: Uppercase letters, digits, and symbols (45 character set)
• Byte: UTF-8 encoded Japanese characters (ひらがな 'あ' = 3 bytes per character)
  • For ASCII characters (1 byte each), multiply the byte value by ~3
  • For theoretical byte capacity, refer to ISO/IEC 18004 Table 7

ECC Level: L

<details><summary>Click to expand full capacity tables</summary>

</details>

ECC Level: M

<details> <summary>Click to expand full capacity tables</summary>

</details>

ECC Level: Q

<details> <summary>Click to expand full capacity tables</summary>

</details>

ECC Level: H

<details> <summary>Click to expand full capacity tables</summary>

</details>

Usage Examples

Basic Usage

Using Builder Pattern

using SkiaSharp.QrCode.Image;

var qrCode = new QRCodeImageBuilder("https://example.com")
    .WithSize(800, 800)
    .WithErrorCorrection(ECCLevel.H)
    .WithQuietZone(4);

var pngBytes = qrCode.ToByteArray();
File.WriteAllBytes("qrcode.png", pngBytes);

Direct File Output

using SkiaSharp.QrCode.Image;
using var stream = File.OpenWrite("qrcode.png");

new QRCodeImageBuilder("https://example.com")
    .WithSize(1024, 1024)
    .WithErrorCorrection(ECCLevel.H)
    .SaveTo(stream);

Advanced Usage

Custom Colors

using SkiaSharp;
using SkiaSharp.QrCode.Image;

new QRCodeImageBuilder("https://example.com")
    .WithSize(800, 800)
    .WithColors(
        codeColor: SKColor.Parse("#000080"),      // Navy
        backgroundColor: SKColor.Parse("#FFE4B5"), // Moccasin
        clearColor: SKColors.Transparent)
    .ToByteArray();

Gradient QR code

using SkiaSharp;
using SkiaSharp.QrCode.Image;

var gradient = new GradientOptions(
    [SKColors.Blue, SKColors.Purple, SKColors.Pink],
    GradientDirection.TopLeftToBottomRight,
    [0f, 0.5f, 1f]);

var qrCode = new QRCodeImageBuilder("https://example.com")
    .WithSize(800, 800)
    .WithErrorCorrection(ECCLevel.H)
    .WithGradient(gradient)
    .WithModuleShape(RoundedRectangleModuleShape.Default, sizePercent: 0.9f);

var pngBytes = qrCode.ToByteArray();

QR code with Logo/Icon

using SkiaSharp;
using SkiaSharp.QrCode.Image;

using var logo = SKBitmap.Decode("logo.png");
var icon = new IconData
{
    Icon = logo,
    IconSizePercent = 15,
    IconBorderWidth = 10,
};

var qrCode = new QRCodeImageBuilder("https://example.com")
    .WithSize(800, 800)
    .WithErrorCorrection(ECCLevel.H) // High ECC recommended for icons
    .WithIcon(icon);

var pngBytes = qrCode.ToByteArray();

Custom Module Shapes

using SkiaSharp;
using SkiaSharp.QrCode.Image;

var qrCode = new QRCodeImageBuilder("https://example.com")
    .WithSize(800, 800)
    .WithModuleShape(CircleModuleShape.Default, sizePercent: 0.95f)
    .WithColors(codeColor: SKColors.DarkBlue);

var pngBytes = qrCode.ToByteArray();

Low-Level Canvas Rendering

For maximum control over rendering:

using SkiaSharp;
using SkiaSharp.QrCode;

// Generate QR data
var qrData = QRCodeGenerator.CreateQrCode("https://example.com", ECCLevel.M, quietZoneSize: 4);

// Create canvas
var info = new SKImageInfo(800, 800);
using var surface = SKSurface.Create(info);
var canvas = surface.Canvas;

// Render QR code
canvas.Render(qrData, info.Width, info.Height);

// Save
using var image = surface.Snapshot();
using var data = image.Encode(SKEncodedImageFormat.Png, 100);
using var stream = File.OpenWrite("qrcode.png");
data.SaveTo(stream);

License

MIT

Acknowledgments

• aloisdeniel/Xam.Forms.QRCode : Qr Sample with Skia
• codebude/QRCoder : QRCode generation algorithms