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qrscan

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One-shot Flutter QR / barcode plugin: open camera, first decode, return a string, close. Also album / path / bytes decode, and QR PNG generation.

This is not an embedded camera widget. If you need a preview, scan window, overlay, torch API, or continuous scan, use mobile_scanner — that race is already over.

This is not a hardware gun. Keyboard wedge → a TextField. OEM broadcast PDA → pda_scanner. Do not open the camera for those.

  • Android CameraX 1.4 + ZXing 3.5.3 (QR, Code 128/39/93, EAN, UPC, ITF, Data Matrix, PDF417, Aztec, Codabar)
  • iOS AVFoundation + Vision
  • Dart 3 / Flutter 3.10+ / Android embedding v2
  • Public Dart API is the same five functions as 0.3.x

Install

dependencies:
  qrscan: ^0.4.0

Dart 3 / Flutter 3.10+. If a mirror still serves 0.3.3:

dependencies:
  qrscan:
    git:
      url: https://github.com/wu9007/qrcode_scanner.git
      ref: 0.4.0

Android

minSdk 21. Camera permission is requested when scan() runs, not at install. Do not add storage permissions — album picking uses the system picker.

Host MainActivity must be embedding v2 (FlutterActivity).

The scanner activity follows the device orientation. It does not lock portrait. If the user has system rotation lock on, the scanner stays put.

iOS

Add to ios/Runner/Info.plist:

<key>NSCameraUsageDescription</key>
<string>Scan QR codes and barcodes</string>
<key>NSPhotoLibraryUsageDescription</key>
<string>Read a code from a photo</string>

Minimum iOS 12.

Landscape on iOS only works if the host app already lists landscape in UISupportedInterfaceOrientations. A plugin cannot override that plist.

Usage

import 'package:qrscan/qrscan.dart' as scanner;

String? cameraScanResult = await scanner.scan();
String? photoScanResult = await scanner.scanPhoto();
String? fromPath = await scanner.scanPath(path);
String? fromBytes = await scanner.scanBytes(bytes);
Uint8List qrPng = await scanner.generateBarCode('https://github.com/wu9007/qrcode_scanner');
Call Returns
scan() Decoded string, or null if the user cancels
scanPhoto() System picker → decode, or null if cancelled
scanPath(path) Decode a local file
scanBytes(bytes) Decode image bytes
generateBarCode(code) QR PNG as Uint8List

That is the whole API. There is no widget, no scan-area parameter, no front-camera switch, no stream, no format filter.

Errors from scan()

Cancel is null. Real failures throw PlatformException:

Dart constant code When
CameraAccessDenied PERMISSION_NOT_GRANTED User denied camera
CameraStartFailed CAMERA_START_FAILED No back camera / driver error
CameraInUse CAMERA_IN_USE Another app already holds the camera

Decoder

QR is tried first (with TRY_HARDER), then other 2D, then 1D. A dense QR is not returned as UPC-E. There is no formats: argument — if you must restrict symbologies, use mobile_scanner.

Latin-1 QR (ISO-8859-1, no ECI) is not forced to UTF-8. Byte segments that are valid UTF-8 with high bits stay UTF-8 (typical Chinese QR).

When not to use this

You want Use instead
Embedded preview / scan window / overlay / continuous scan / web / desktop mobile_scanner
Only 1D / only QR / a format list mobile_scanner formats:
Industrial PDA trigger that broadcasts an Intent pda_scanner
Gun set to keyboard (HID) wedge Any TextField. No plugin.

Three mutually exclusive paths: camera one-shot (this plugin) · OEM broadcast (pda_scanner) · HID keyboard (nothing). Mixing them is how field apps “break”.

0.3 → 0.4

Before After
Android only, embedding v1 leftovers Android + iOS, embedding v2
com.github.leyan95:android-zxingLibrary (JitPack, often missing) com.google.zxing:core:3.5.3 + CameraX 1.4
iOS was a TODO Vision actually scans
Storage permissions Camera + system photo picker
SDK <3.0.0 Dart 3 / Flutter 3.10+
Torch crash on devices with no flash CameraX enableTorch, toast if unavailable
Scanner locked portrait (tablets / landscape broken) Follows device rotation; overlay recenters
Dense QR read as UPC-E QR (TRY_HARDER) before 1D
Latin-1 QR forced to UTF-8 BYTE_SEGMENTS → ISO-8859-1 unless valid UTF-8
Camera busy / bind fail → black Activity CAMERA_IN_USE / CAMERA_START_FAILED to Dart

Public Dart API is unchanged. The two new error constants are optional.

License

MIT. Created by Shusheng.

Libraries

qrscan