Dart Requires Chilkat v11.7.0+

Generate a QR Code PNG in Memory

See more QR Code Examples

Demonstrates getting a QR code image without writing a file. With no output options the result is a PNG returned as base64 in outputs[0].base64 of the response. The example decodes it into a BinData, which holds the bytes of the PNG to send in an HTTP response, store in a database, attach to an email, or save. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final json = CkJsonObject();
  json.updateString('payload.text', 'https://www.chilkatsoft.com/');
  json.updateInt('render.moduleSize', 6);

  final fmt = CkFormats();
  final jsonOut = CkJsonObject();
  try {
    fmt.qrCode('generate', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('format: ${jsonOut.stringOf('outputs[0].format')}');
  print('MIME type: ${jsonOut.stringOf('outputs[0].mimeType')}');
  print('image: ${jsonOut.intOf('outputs[0].width')} x ${jsonOut.intOf('outputs[0].height')} pixels');

  // outputs[0].base64 is the PNG file, base64 encoded.
  final bdPng = CkBinData();
  try {
    bdPng.appendEncoded(jsonOut.stringOf('outputs[0].base64'), 'base64');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('PNG bytes: ${bdPng.numBytes}');

  // The BinData holds the image.  Here it is simply saved.
  try {
    bdPng.writeFile('qa_output/qr_in_memory.png');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // The PNG held in bdPng:

  // 

  // Sample output:

  // format: png
  // MIME type: image/png
  // image: 222 x 222 pixels
  // PNG bytes: 877
}