Rotate With Handler

main.dart

import 'dart:math';

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: RotateText(),
    );
  }
}

class RotateText extends StatefulWidget {
  RotateText({Key key}) : super(key: key); // changed

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

class _RotateTextState extends State<RotateText> {
  double finalAngle = 0.0;
  double oldAngle = 0.0;
  double upsetAngle = 0.0;

  @override
  Widget build(BuildContext context) {
    return _defaultApp(context);
  }

  Offset centerOfGestureDetector;

  _defaultApp(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Single finger Rotate text'), // changed
      ),
      body: Center(
        child: Column(
          children: <Widget>[
            Text(finalAngle.toString()),
            Text(rotationalChange.toString()),
            Container(
                color: Colors.red,
                width: 80,
                height: 80,
                padding: EdgeInsets.all(10),
                margin: EdgeInsets.only(top: 20),
                child: LayoutBuilder(builder: (context, constraints) {
//                   print('1 $constraints');
                  centerOfGestureDetector = Offset(
                      constraints.maxWidth / 2, constraints.maxHeight / 2);
                  return Transform.rotate(
                    angle: finalAngle,
                    child: Stack(
                      children: [
                        Container(
                          height: 100.0,
                          width: 100.0,
                          child: Image.network(
                            'https://picsum.photos/250?image=9',
                          ),
                        ),
                        Positioned(
                          top: 0,
                          right: 0,
                          child: Container(
                            color: Colors.white,
                            child: GestureDetector(
                              onPanUpdate: _panHandler,
                              behavior: HitTestBehavior.translucent,
//                               onPanStart: (details) {
//                                 final touchPositionFromCenter =
//                                     details.localPosition -
//                                         centerOfGestureDetector;
//                                 upsetAngle = oldAngle -
//                                     touchPositionFromCenter.direction;
//                               },
//                               onPanEnd: (details) {
//                                 setState(
//                                   () {
//                                     oldAngle = finalAngle;
//                                   },
//                                 );
//                               },
//                               onPanUpdate: (details) {
//                                 final touchPositionFromCenter =
//                                     details.localPosition -
//                                         centerOfGestureDetector;

//                                 print(
//                                     '${details.localPosition}  -  ${touchPositionFromCenter.direction}  -  $centerOfGestureDetector');
//                                 setState(
//                                   () {
//                                     finalAngle =
//                                         touchPositionFromCenter.direction +
//                                             upsetAngle;
//                                   },
//                                 );
//                               },
//                               onPanUpdate: (details) {
//                                 Offset off = new Offset(constraints.maxWidth-details.localPosition.dx, details.localPosition.dy);
//                                 print('${details.localPosition} - ${centerOfGestureDetector} - ${off}');
//                                 final touchPositionFromCenter =
//                                     off -
//                                         centerOfGestureDetector;
                                
// //                                 print(
// //                                     '${details.localPosition}  -  ${touchPositionFromCenter.direction}  -  $centerOfGestureDetector');
                                
// //                                 print('${details.localPosition}  -  ${touchPositionFromCenter.direction *
// //                                     180 /
// //                                     pi}  -  $centerOfGestureDetector');
//                                 setState(
//                                   () {
//                                     finalAngle =
//                                         touchPositionFromCenter.direction;
//                                   },
//                                 );
//                               },
                              child: Container(
                                width: 16,
                                height: 16,
                                child: Icon(Icons.add, size: 12)
                              ),
                            ),
                          ),
                        ),
                      ],
                    ),
                  );
                })),
            Row(
              mainAxisSize: MainAxisSize.min,
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Text("180"),
                Container(
                  width: 150,
                  height: 150,
                  color: Colors.grey,
                  margin: EdgeInsets.all(30.0),
                  child: LayoutBuilder(
                    builder: (context, constraints) {
//                       print('2 $constraints');
                      return GestureDetector(
                        behavior: HitTestBehavior.translucent,
                        onPanUpdate: (details) {
                          Offset centerOfGestureDetector = Offset(
                              constraints.maxWidth / 2,
                              constraints.maxHeight / 2);
                          final touchPositionFromCenter =
                              details.localPosition - centerOfGestureDetector;
//                           print(touchPositionFromCenter.direction * 180 / pi);
                          
                                print(
                                    '${details.localPosition}  -  ${touchPositionFromCenter.direction}  -  $centerOfGestureDetector');
                          setState(
                            () {
                              finalAngle = touchPositionFromCenter.direction;
                            },
                          );
                        },
                        child: Transform.rotate(
                          angle: finalAngle,
                          child: Icon(
                            Icons.arrow_forward,
                            color: Colors.white,
                            size: 100,
                          ),
                        ),
                      );
                    },
                  ),
                ),
                Text("0")
              ],
            )
          ],
        ),
      ),
    );
  }

  double rotationalChange = 0;
  void _panHandler(DragUpdateDetails d) {
    /// Pan location on the wheel
    bool onTop = true;
    bool onLeftSide = true;
    bool onRightSide = !onLeftSide;
    bool onBottom = !onTop;

//     print('$onTop $onLeftSide $onRightSide $onBottom');

    /// Pan movements
    bool panUp = d.delta.dy <= 0.0;
    bool panLeft = d.delta.dx <= 0.0;
    bool panRight = !panLeft;
    bool panDown = !panUp;

    /// Absoulte change on axis
    double yChange = d.delta.dy.abs();
    double xChange = d.delta.dx.abs();

    /// Directional change on wheel
    double verticalRotation = (onRightSide && panDown) || (onLeftSide && panUp)
        ? yChange
        : yChange * -1;

    double horizontalRotation =
        (onTop && panRight) || (onBottom && panLeft) ? xChange : xChange * -1;

    // Total computed change
    rotationalChange = verticalRotation + horizontalRotation;

    bool movingClockwise = rotationalChange > 0;
    bool movingCounterClockwise = rotationalChange < 0;

    // Now do something interesting with these computations!
    print('$verticalRotation $horizontalRotation $rotationalChange $movingClockwise $movingCounterClockwise');

    setState(() {});
  }
}