anchor.diff:  import 'package:flutter/rendering.dart';
   import 'package:provider/provider.dart';
   
  -class StudentIdCard extends StatelessWidget {
  +class StudentIdCard extends StatefulWidget {
  +  @override
  +  _StudentIdCardState createState() => _StudentIdCardState();
  +}
  +
  +class _StudentIdCardState extends State<StudentIdCard> {
     String cardId = "student_id";
  -  var barcodeImage;
  -
  +
  +  /// Pop up barcode
     createAlertDialog(BuildContext context, Column image) {
       return showDialog(
           context: context,
           builder: (context) {
             return AlertDialog(
  -            title: Text("Student ID"),
  +            backgroundColor: Colors.white,
  +            title: Text(
  +              "Student ID",
  +              style: TextStyle(color: Colors.black),
  +            ),
               content: Container(
                 child: image,
               ),
               actions: <Widget>[
                 FlatButton(
  -                  child: Icon(Icons.close),
  +                  child: Icon(
  +                    Icons.close,
  +                    color: Colors.black,
  +                  ),
                     onPressed: () {
                       Navigator.of(context).pop();
                     })
  
positive.code:         data: cardNumber,
          width: SizeConfig.safeBlockVertical * 60,
          height: 80,
          style: TextStyle(letterSpacing: SizeConfig.safeBlockVertical * 3, fontSize: 0, color: Colors.white),
        );
      } else {
        barcodeWithText = BarcodeWidget(
  
negative.code:     blockSizeVertical = screenHeight / 100;
  
      _safeAreaHorizontal =
      _mediaQueryData.padding.left + _mediaQueryData.padding.right;
      _safeAreaVertical =
      _mediaQueryData.padding.top + _mediaQueryData.padding.bottom;
      safeBlockHorizontal = (screenWidth - _safeAreaHorizontal) / 100;
      safeBlockVertical = (screenHeight - _safeAreaVertical) / 100;
      }
    }
  
  