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xue_hua_qr_code #

Out-of-the-box QR code widget for Flutter. Pure Dart — no native dependencies, no platform channels.

XueHuaQrCode(value: 'https://example.com')

That is all you need: a scannable black-on-white QR code that adapts to its parent constraints.

Features #

• One required parameter — pass value, get a standard QR code with sensible defaults
• Styling — square / circle / rounded modules, colors, gradients, proportional corner radius and gaps
• Center logo — ImageProvider based, sized as a fraction of the QR code, identical in widget and export
• Automatic mask selection — the best of 8 mask patterns is chosen per ISO/IEC 18004 penalty rules
• Robust error handling — empty / oversized content falls back to errorBuilder; a failing logo (e.g. network error) degrades to a plain, still-scannable QR code
• Export — XueHuaQrCode.toImage() and XueHuaQrCode.toPngBytes() share the exact painter used on screen

Installation #

dependencies:
  xue_hua_qr_code: ^lasted_version

Basic usage #

import 'package:xue_hua_qr_code/xue_hua_qr_code.dart';

// Adapts to the parent's shortest bounded side.
XueHuaQrCode(value: 'https://example.com')

// Fixed size.
XueHuaQrCode(value: 'https://example.com', size: 240)

Advanced usage #

Custom style #

XueHuaQrCode(
  value: 'https://example.com',
  size: 240,
  style: const QrStyle(
    shape: QrModuleShape.roundedSquare,
    moduleRadius: 0.4,          // fraction of a module, 0~0.5
    moduleGap: 0.15,            // fraction of a module, 0~0.5
    gradient: LinearGradient(colors: [Colors.pink, Colors.blue]),
    padding: EdgeInsets.all(12), // quiet zone
  ),
)

With a logo #

XueHuaQrCode(
  value: 'https://example.com',
  size: 240,
  style: const QrStyle(shape: QrModuleShape.roundedSquare),
  logo: const QrLogo(
    image: AssetImage('assets/logo.png'), // NetworkImage / MemoryImage also work
    scale: 0.22,      // fraction of the QR side, max 0.35
    padding: 6,
    borderRadius: 8,
  ),
  // Error correction is automatically raised to `high` when a logo is present.
)

If the logo fails to load (missing asset, network error), the widget renders the full QR code without the logo — it never leaves an unscannable hole.

Error handling #

XueHuaQrCode(
  value: userInput, // may be empty or too long
  errorBuilder: (context, error, stackTrace) => const Icon(Icons.error),
)

Export #

// PNG bytes — save to a file or show with Image.memory.
final bytes = await XueHuaQrCode.toPngBytes(
  'https://example.com',
  size: 512,
  style: const QrStyle(shape: QrModuleShape.circle),
);

// dart:ui Image.
final image = await XueHuaQrCode.toImage('https://example.com', size: 512);

API reference #

XueHuaQrCode #

QrStyle #

QrLogo #

QrErrorLevel #

low (~7%), medium (~15%), quartile (~25%), high (~30%) — the approximate share of data that can be recovered.

Export #

Both use the same painter as the widget — what you see is what you export.

Example app #

cd example
flutter run

Five tabs demonstrate basic, circle, rounded, gradient, and logo styles, plus PNG export.

License #

MIT — encoding internals ported from qrcode-kotlin.