qr_image_exporter #

An extension for the popular qr.dart package, providing a simple, robust way to export QR code modules as PNG byte data.

Features #

This package adds the toPngBytes() method as an extension on the QrImage class from package:qr.

• Simple Export: Easily generate a Uint8List (PNG byte data) from any QrImage instance.
• Highly Configurable: Customize the output image with parameters for:
  • Module Size: Set the pixel size of each QR code dot.
  • Margin: Define the border size around the QR code.
  • Colors: Specify custom ARGB colors for the dark and light modules.

Getting Started #

Installation #

Add qr_image_exporter to your project's pubspec.yaml file:

dependencies:
  qr_image_exporter: ^1.0.0 # Use the latest version

Usage #

Import the qr_image_exporter package. The necessary classes (QrCode, QrImage) are automatically exposed, allowing you to use the toPngBytes() extension method immediately.

import 'dart:io';
import 'dart:typed_data';
import 'package:qr_image_exporter/qr_image_exporter.dart';

void main() {
  // 1. Generate the core QrImage data
  final QrCode qrCode = QrCode.fromData(
    data: 'https://pub.flutter-io.cn/packages/qr_image_exporter',
    errorCorrectLevel: QrErrorCorrectLevel.M,
  );
  final QrImage qrImage = QrImage(qrCode);

  // 2. Use the 'toPngBytes' extension method to export
  final Uint8List? pngBytes = qrImage.toPngBytes(
    // Optional: Customize the image output
    moduleSize: 8, // Larger dots (higher resolution)
    margin: 30, // Larger border
    darkColor: 0xFF0057B8, // Example: Blue
    lightColor: 0xFFF0DA49, // Example: Yellow
  );

  if (pngBytes != null) {
    // Example: Save the byte data to a file
    File('example_qr_code.png').writeAsBytesSync(pngBytes);
    print('QR code successfully exported!');
  }
}

Example Output #

Here is the QR code generated by the example above (using Blue/Yellow custom colors):

API Reference #

QrImageExporter Extension #

The extension provides one main method:

toPngBytes

Uint8List? toPngBytes({
  int moduleSize = 4,
  int margin = 20,
  int darkColor = 0xFF000000,
  int lightColor = 0xFFFFFFFF,
})

Returns: A Uint8List containing the PNG image data, or null if encoding fails.

Contributing #

Contributions are welcome! Feel free to open an issue or submit a pull request if you have suggestions or bug fixes.

This package was created to address the long-standing image export request from the original qr.dart package (Issue #62).