PNG and SVG rendering

Utils.toImage(qr, scale, border) renders a QrCode as BufferedImage. scale is pixels per module and must be positive; border is the light quiet-zone width in modules and must be non-negative. A border of four is the usual interoperable choice.

QrCode qr = QrCode.encodeText("Invoice #2026-031", Ecc.QUARTILE);
BufferedImage image = Utils.toImage(qr, 8, 4, 0xFFFFFF, 0x17365D);
Utils.writePng(image, "invoice-qr.png");

The colors are 24-bit 0xRRGGBB. Ensure strong contrast. writePng() delegates to ImageIO.write() and can throw IOException; choose, validate, and authorize output locations in application code.

SVG

toSvgString() returns XML rather than writing a file. SVG preserves sharp module edges at any scale and is usually suitable for documents or browser assets.

import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;

String svg = Utils.toSvgString(qr, 4, "#FFFFFF", "#111827");
Files.write(Paths.get("invoice-qr.svg"), svg.getBytes(StandardCharsets.UTF_8));

The SVG method inserts CSS color strings into its output; use fixed trusted values, not unsanitized request parameters. The helpers do not embed logos or modify encoded data. For custom canvas, PDF, or a QrCodeFast result, iterate getModule(x, y) and implement rendering in the caller.

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QR Code

PNG and SVG rendering

SVG