flutter toggle password animation v2

main.dart

import 'package:flutter/material.dart';
//create by Amirreza salimi  https://gist.github.com/amirrezasalimi/48132d9330f53672a894829961cb727b/
class ToggleInput extends StatefulWidget {
  @override
  ToggleInputState createState() => ToggleInputState();
}

class ToggleInputState extends State<ToggleInput>
    with TickerProviderStateMixin {
  bool isHidden = false;
  Animation<double> scaleF;
  AnimationController scaleAnim;

  Animation<Offset> eyeF;

  @override
  void initState() {
    super.initState();
    double maxScale = 14;
    scaleAnim = AnimationController(
        vsync: this, duration: Duration(milliseconds: 300), value: 1);
    scaleF = Tween<double>(begin: 1, end: maxScale).animate(scaleAnim);
    scaleAnim.addListener(() {
      setState(() {});
    });
    //+3,-3 to -3,0
    eyeF = Tween<Offset>(begin: Offset(3, -3), end: Offset(-3, 0))
        .animate(scaleAnim);
  }

  @override
  Widget build(BuildContext context) {
    Size size = MediaQuery.of(context).size;
    return Container(
      child: FractionallySizedBox(
          widthFactor: 0.85,
          child: Container(
            height: 80,
            child: ClipRRect(
              borderRadius: BorderRadius.circular(18.0),
              clipBehavior: Clip.antiAliasWithSaveLayer,
              child: Stack(
                children: [
                  Container(
                    decoration: BoxDecoration(
                      color: Color(0xff121726),
                    ),
                  ),
                  Positioned(
                    right: 10,
                    top: (80 - 50) / 2,
                    child: Transform.scale(
                      scale: scaleF.value,
                      child: SizedBox(
                          width: 50,
                          height: 50,
                          child: Container(
                            decoration: BoxDecoration(
                                borderRadius: BorderRadius.circular(80),
                                color: Colors.white),
                          )),
                    ),
                  ),
                  Positioned(
                    left: 10,
                    top: (80 - 27) / 2,
                    child: Icon(
                      Icons.lock,
                      color: isHidden ? Colors.white : Colors.black,
                      size: 27,
                    ),
                  ),
                  Positioned(
                      left: 27 + 12.0,
                      top: (80 - 50) / 2,
                      child: Container(
                        width: size.width * 0.60,
                        child: TextField(
                          textAlign: TextAlign.left,
                          obscureText: isHidden,
                          cursorColor: isHidden ? Colors.white : Colors.black,
                          controller: TextEditingController(text: "f2bfd5g"),
                          style: TextStyle(
                              color:
                                  isHidden ? Color(0xff575cba) : Colors.black,
                              fontSize: isHidden ? 28 : 20),
                          decoration: InputDecoration(
                            contentPadding: EdgeInsets.only(left: 5),
                            border: InputBorder.none,
                            focusedBorder: InputBorder.none,
                            enabledBorder: InputBorder.none,
                            errorBorder: InputBorder.none,
                            disabledBorder: InputBorder.none,
                          ),
                        ),
                      )),
                  Positioned(
                    right: 10,
                    top: (80 - 50) / 2,
                    child: GestureDetector(
                      onTap: () {
                        setState(() {
                          if (!isHidden) {
                            scaleAnim.reverse();
                          } else {
                            scaleAnim.forward();
                          }
                          isHidden = !isHidden;
                        });
                      },
                      child: Container(
                          width: 50,
                          height: 50,
                          decoration: BoxDecoration(
                              color: Colors.transparent,
                              borderRadius: BorderRadius.circular(80)),
                          child: Center(
                            child: SizedBox(
                              width: 30,
                              height: 35,
                              child: CustomPaint(
                                painter: Eye(eyeF.value),
                              ),
                            ),
                          )),
                    ),
                  )
                ],
              ),
            ),
          )),
    );
  }
}

class Eye extends CustomPainter {
  Offset eyeMove;
  Eye(this.eyeMove);

  @override
  void paint(Canvas canvas, Size size) {
    Paint eye_paint = Paint()
      ..style = PaintingStyle.stroke
      ..strokeWidth = 2
      ..color = Color(0xff575cba);

    double marginTop = 5;
    double marginSides = 3;

    //top
    Path top_h = Path();
    top_h.moveTo(marginSides, (size.height / 2) + marginTop);

    top_h.quadraticBezierTo(size.width / 2, (size.height / 2) - (marginTop * 2),
        size.width - marginSides, (size.height / 2) + marginTop);

    top_h.moveTo(size.width - marginSides, (size.height / 2) + marginTop);

    //eyelash +
    double c = (size.height / 2) - marginTop / 2;

    //1
    top_h.moveTo(marginSides + 4, c + 3);
    top_h.lineTo(marginSides, c - 3);

    //2
    top_h.moveTo(size.width / 2, c);
    top_h.lineTo(size.width / 2, c - 7);

    //3
    top_h.moveTo(size.width - marginSides - 4, c + 3);
    top_h.lineTo(size.width - marginSides, c - 3);

    //eyeball
    top_h.close();
    Paint eyeball_paint = Paint()
      ..style = PaintingStyle.fill
      ..color = Color(0xff575cba);

    canvas.drawCircle(
        Offset(size.width / 2 + eyeMove.dx,
            c + marginTop + (marginTop / 2) + eyeMove.dy),
        3.4,
        eyeball_paint);

    canvas.drawPath(top_h, eye_paint);

    //bottom
    Path bottom_h = Path();
    bottom_h.moveTo(marginSides, (size.height / 2) + marginTop);

    bottom_h.quadraticBezierTo(size.width / 2, size.height,
        size.width - marginSides, (size.height / 2) + marginTop);
    canvas.drawPath(bottom_h, eye_paint);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    return this != oldDelegate;
  }
}

void main() {
  runApp(
    MaterialApp(
        home: Scaffold(
            backgroundColor: Colors.blue,
            body: Container(
              child: Center(child: ToggleInput()),
            ))),
  );
}