Barcodes & QR Codes | Headless Rendering

BarcodeRenderer is a static, stateless class that produces barcode output directly — no view, no component, no platform dependency. It’s the engine the MAUI views and Blazor components both call, exposed for use from view models, services, PDF builders, background jobs, and server code.

using Shiny.Controls.Barcodes;

Everything here lives in the shared Shiny.Controls.Barcodes package, which is pulled in transitively by both the MAUI and Blazor packages — so if you’ve installed either UI package, the renderer is already available.

The API

Three static methods, all overloads of “encode content as format using options”:

// Raw PNG bytes
byte[] RenderPng(string content, BarcodeFormat format, BarcodeRenderOptions? options = null);

// SVG markup (a complete <svg>…</svg> string)
string RenderSvg(string content, BarcodeFormat format, BarcodeRenderOptions? options = null);

// data: URI — pick PNG or SVG encoding
string RenderDataUri(string content, BarcodeFormat format, BarcodeImageFormat imageFormat, BarcodeRenderOptions? options = null);

options is optional — omit it to use the defaults. All three calls are pure and thread-safe; call them from anywhere.

var opts = new BarcodeRenderOptions
{
    PixelWidth = 600,
    PixelHeight = 200,
    Margin = 10,
    ForegroundColor = "#000000",
    BackgroundColor = "#FFFFFF",
    QRErrorCorrection = QRErrorCorrection.High // QR only — ignored for other formats
};

byte[] png     = BarcodeRenderer.RenderPng("Hello", BarcodeFormat.QRCode, opts);
string svg     = BarcodeRenderer.RenderSvg("Hello", BarcodeFormat.QRCode, opts);
string dataUri = BarcodeRenderer.RenderDataUri("Hello", BarcodeFormat.QRCode, BarcodeImageFormat.Png, opts);

BarcodeRenderOptions

Property	Type	Default	Description
PixelWidth	int	250	Output bitmap width
PixelHeight	int	250	Output bitmap height
Margin	int	10	Quiet-zone padding in pixels
ForegroundColor	string	"#000000"	Hex — #RGB, #RRGGBB, or #AARRGGBB (alpha is stripped)
BackgroundColor	string	"#FFFFFF"	Hex — same formats as above
QRErrorCorrection	QRErrorCorrection	Medium	QR-only; ignored for all other formats

Color parsing

Colors are parsed by an internal hex parser that accepts 3-, 6-, and 8-digit hex (with or without a leading #). For 8-digit #AARRGGBB, the alpha channel is dropped — barcodes are rendered fully opaque. Anything it can’t parse falls back to black.

Defaults differ from the views

BarcodeRenderOptions defaults to 250 × 250 (square), which suits QR codes. The MAUI/Blazor views default to 400 × 150 (a wide 1D shape). When rendering 1D symbologies headlessly, set a wider PixelWidth/PixelHeight yourself.

Recipes

Save a QR code to disk

byte[] png = BarcodeRenderer.RenderPng("https://shinylib.net", BarcodeFormat.QRCode);
File.WriteAllBytes("join.png", png);

Embed in a PDF or report

Most PDF libraries accept a byte[] or Stream for an image:

var png = BarcodeRenderer.RenderPng(invoice.Number, BarcodeFormat.Code128, new()
{
    PixelWidth = 600,
    PixelHeight = 160
});
pdf.AddImage(png); // e.g. QuestPDF, iText, etc.

Inline a barcode in an HTML email

A data URI drops straight into an <img src="…">, so the image travels with the message body:

var dataUri = BarcodeRenderer.RenderDataUri(
    order.Tracking,
    BarcodeFormat.Code128,
    BarcodeImageFormat.Png   // most email clients render PNG more reliably than inline SVG
);
var html = $"<img src=\"{dataUri}\" alt=\"Tracking {order.Tracking}\" />";

Vector output for a print template

string svg = BarcodeRenderer.RenderSvg(label.Sku, BarcodeFormat.DataMatrix, new()
{
    PixelWidth = 300,
    PixelHeight = 300
});
// drop `svg` directly into your XAML/HTML print layout

How the PNG encoder works

The PNG path doesn’t depend on SkiaSharp or System.Drawing. It encodes the ZXing bit-matrix into a PNG by hand: a custom zlib deflate stream, CRC32 for the chunk checksums, and Adler32 for the zlib trailer. That’s what keeps the package fully managed and AOT/trim-safe across every target — including iOS and Blazor WASM, where System.Drawing isn’t an option.

The SVG path emits one <path> built from horizontal runs of dark modules, with shape-rendering="crispEdges" so it never anti-aliases the edges. That makes the SVG both small and pixel-sharp at any scale.

See also

• .NET MAUI Usage and Blazor Usage — when you want a control instead of bytes
• Symbologies — choosing a format and its input rules