bar Code preview

class CodePreviewPage extends StatefulWidget {
  final Product product;
  const CodePreviewPage({
    Key? key,
    required this.product,
  }) : super(key: key);

  @override
  _CodePreviewPageState createState() => _CodePreviewPageState();
}

class _CodePreviewPageState extends State<CodePreviewPage> {
  GlobalKey barCodeKey = new GlobalKey();
  GlobalKey qrCodeKey = new GlobalKey();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        elevation: 1,
        centerTitle: true,
        backgroundColor: Colors.white,
        leading: IconButton(
          icon: Icon(
            Icons.arrow_back_ios,
            color: Colors.black,
          ),
          onPressed: () {
            Navigator.of(context).pop();
          },
        ),
        title: Text(
          "Bar Code Preview",
          style: TextStyle(
            color: Colors.black,
          ),
        ),
      ),
      body: SingleChildScrollView(
        child: _buildItems(),
      ),
      bottomNavigationBar: _buildBottomNavigationBar(),
    );
  }

  Widget _buildItems() {
    return Container(
      padding: EdgeInsets.all(20),
      child: Column(
        children: <Widget>[
          _buildBarCodeSection(),
          _buildQrCodeSection(),
        ],
      ),
    );
  }

  Widget _buildBarCodeSection() {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: <Widget>[
            Text(
              "Bar Code",
              style: TextStyle(
                fontSize: 20,
                fontWeight: FontWeight.bold,
              ),
            ),
            TextButton(
              onPressed: () {},
              child: Text("Print"),
            ),
            TextButton(
              onPressed: () {
                _saveBarCode();
              },
              child: Text("Save"),
            ),
          ],
        ),
        SizedBox(
          height: 20,
        ),
        Center(
          child: RepaintBoundary(
            key: barCodeKey,
            child: BarcodeWidget(
              data: widget.product.productId!,
              barcode: Barcode.code128(),
              width: 200,
              height: 200,
              drawText: false,
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildQrCodeSection() {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Row(
          mainAxisAlignment: MainAxisAlignment.spaceBetween,
          children: <Widget>[
            Text(
              "QR Code",
              style: TextStyle(
                fontSize: 20,
                fontWeight: FontWeight.bold,
              ),
            ),
            TextButton(
              onPressed: () {},
              child: Text("Print"),
            ),
          ],
        ),
        SizedBox(
          height: 20,
        ),
        BarcodeWidget(
          data: widget.product.productId!,
          barcode: Barcode.qrCode(),
        ),
      ],
    );
  }

  Widget _buildBottomNavigationBar() {
    return Container(
      padding: EdgeInsets.all(20),
      child: BlackButton(
        label: "Save",
        onPressed: () {},
      ),
    );
  }

  Future<File> _saveBarCode() async {
    RenderRepaintBoundary boundary =
        barCodeKey.currentContext!.findRenderObject() as RenderRepaintBoundary;
    ui.Image image = await boundary.toImage();
    ByteData? byteData = await image.toByteData(format: ui.ImageByteFormat.png);
    Uint8List pngBytes = byteData!.buffer.asUint8List();
    final tempPath = (await getTemporaryDirectory()).path;
    final path = tempPath + "qr.png";
    File imgFile = File(path);
    return imgFile.writeAsBytes(pngBytes);
  }
}