使用的插件是

scan: any

要识别微信的二维码或者群聊的二维码;
现在遇到问题是有的用户保存微信图片时,使用了彩色的图片,在iOS16.x可以识别,但是15.x识别不到二维码,返回为null;

Scan.parse(path)

图片是绝对没问题的
使用Photoshop,把彩色图片反相后,15.x就可以识别了
具体操作代码如下

图片反相:

static Future<ui.Image> invertImage(ui.Image image) async {
    final int width = image.width;
    final int height = image.height;

    final ui.PictureRecorder recorder = ui.PictureRecorder();
    final ui.Canvas canvas = ui.Canvas(recorder);

    final ui.Paint paint = ui.Paint();
    // final maskFilter = ui.MaskFilter.blur(
    //   ui.BlurStyle.normal,
    //   ui.BlurStyle.normal.convertRadiusToSigma(1.0),
    // );

    final ui.Rect rect =
        ui.Rect.fromLTWH(0, 0, width.toDouble(), height.toDouble());

    final Offset offset = Offset(0, 0);

    canvas.drawImage(image, offset, paint);
    // canvas.drawImage
    paint.color = ui.Color.fromRGBO(255, 255, 255, 1);
    paint.blendMode = ui.BlendMode.difference;
    canvas.drawRect(rect, paint);

    final ui.Picture picture = recorder.endRecording();
    final ui.Image newImage = await picture.toImage(width, height);

    return newImage;
  }

识别

//扫描二维码
  static Future<String?> scanImageFile(String imagePath) async {
    try {
      if (imagePath.isEmpty) return null;
      String? result = await Scan.parse(imagePath);
      if (result == null) {
        //第一次没有扫描到二维码
        print('ScanUtils第一次没有扫描到二维码$imagePath');
        File file = File(imagePath);
        if (!file.existsSync()) {
          return null;
        }
        //图片存在
        final Uint8List imgData = file.readAsBytesSync();
        final ui.Codec codec = await ui.instantiateImageCodec(imgData);
        final ui.FrameInfo frameInfo = await codec.getNextFrame();
        ui.Image image = await ImageUtils.invertImage(frameInfo.image);
        Directory dir = await getTemporaryDirectory();
        String path = dir.path + '/${genUUID(16)}.png';

        final ByteData? byteData =
            await image.toByteData(format: ui.ImageByteFormat.png);
        if (byteData != null) {
          final Uint8List pngBytes = byteData.buffer.asUint8List();
          await File(path).writeAsBytes(pngBytes);
        }
        File(path).writeAsBytesSync(byteData!.buffer.asUint8List());

        if (!File(path).existsSync()) return null;
        print('ScanUtils扫码反相的${path}');
        result = await Scan.parse(path);
        if (result == null) {
          return null;
        }
        return result;
      }
      print('ScanUtils第一次扫描到了$result');
      return result;
    } catch (e) {
      print('ScanUtils扫描错误${e.toString()}');
      return null;
    }
  }

done