Rotate text or image using button gesture in flutter

Question

Now, the image is smoothly rotating only from left to right when I make a gesture of 360 degree.

Required result:

Should rotate from right to left when we make a gesture of 360 degree.
Done: Should rotate from right to left when we make a gesture of 360 degree.
Once we start rotating from left to right at some point and again back to right to left it should rotate from either direction from which the gesture is made.

  import 'dart:math';

  import 'package:flutter/material.dart';

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

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

  class _RotateImageState extends State<RotateImage> {
    double finalAngle = 0.0;

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

    _defaultApp(BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: Text('Single finger Rotate text'), // changed
        ),
        body: Center(
          child: Column(
            children: <Widget>[
              Container(
                color: Colors.red,
                padding: EdgeInsets.all(10),
                margin: EdgeInsets.only(top: 50),
                child: Transform.rotate(
                  angle: finalAngle,
                  origin: Offset(0, 0),
                  child: Container(
                    height: 100.0,
                    width: 100.0,
                    child: Image.network(
                      'https://picsum.photos/250?image=9',
                    ),
                  ),
                ),
              ),
              GestureDetector(
                onPanStart: (detials) {},
                onPanEnd: (detials) {},
                onPanUpdate: (details) {
                  setState(
                    () {
                      finalAngle += details.delta.distance * -pi / 180;
                    },
                  );
                },
                child: Container(
                  margin: EdgeInsets.only(top: 30),
                  color: Colors.black54,
                  width: 50,
                  height: 50,
                  child: Icon(
                    Icons.rotate_left,
                    color: Colors.white,
                  ),
                ),
              )
            ],
          ),
        ),
      );
    }
  }

You should try on a device to see the actual outcome of animation — Tizianoreica, Jan 25 '20 at 09:19
Already tried on the real device. Did you try running the code? — jazzbpn, Jan 25 '20 at 10:12
Do you want it to rotate while you're making circles with your finger? Because that's very different approach. My current answer is based on straight line drags. — easeccy, Jan 26 '20 at 10:55
Yes. Exactly!! I want to rotate the widget while we make circles with our finger. — jazzbpn, Jan 26 '20 at 11:06

Crazy Lazy Cat · Accepted Answer · 2020-01-28T08:33:42.777

Here if you do gesture (with one finger) in circle around the icon, it will rotate.

Source Code 1: (Here the angle is based on finger position from the center of GestureDetector)

Demo: DartPad,

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;

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

  _defaultApp(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Single finger Rotate text'), // changed
      ),
      body: Center(
        child: Column(
          children: <Widget>[
            Container(
              color: Colors.red,
              padding: EdgeInsets.all(10),
              margin: EdgeInsets.only(top: 50),
              child: Transform.rotate(
                angle: finalAngle,
                child: Container(
                  height: 100.0,
                  width: 100.0,
                  child: Image.network(
                    'https://picsum.photos/250?image=9',
                  ),
                ),
              ),
            ),
            Container(
              width: 250,
              height: 250,
              color: Colors.grey,
              margin: EdgeInsets.all(30.0),
              child: LayoutBuilder(
                builder: (context, 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);
                      setState(
                            () {
                          finalAngle = touchPositionFromCenter.direction;
                        },
                      );
                    },
                    child: Transform.rotate(
                      angle: finalAngle,
                      child: Icon(
                        Icons.arrow_forward,
                        color: Colors.white,
                        size: 200,
                      ),
                    ),
                  );
                },
              ),
            )
          ],
        ),
      ),
    );
  }
}

Source Code 2: (Here the angle is persisted and will continue update on every onPanStart)

Demo: DartPad,

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 offsetAngle = 0.0;

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

  _defaultApp(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Single finger Rotate text'), // changed
      ),
      body: Center(
        child: Column(
          children: <Widget>[
            Container(
              color: Colors.red,
              padding: EdgeInsets.all(10),
              margin: EdgeInsets.only(top: 50),
              child: Transform.rotate(
                angle: finalAngle,
                child: Container(
                  height: 100.0,
                  width: 100.0,
                  child: Image.network(
                    'https://picsum.photos/250?image=9',
                  ),
                ),
              ),
            ),
            Container(
              width: 250,
              height: 250,
              color: Colors.grey,
              margin: EdgeInsets.all(30.0),
              child: LayoutBuilder(
                builder: (context, constraints) {
                  return GestureDetector(
                    behavior: HitTestBehavior.translucent,
                    onPanStart: (details) {
                      Offset centerOfGestureDetector = Offset(
                          constraints.maxWidth / 2, constraints.maxHeight / 2);
                      final touchPositionFromCenter =
                          details.localPosition - centerOfGestureDetector;
                      offsetAngle =
                          touchPositionFromCenter.direction - finalAngle;
                    },
                    onPanUpdate: (details) {
                      Offset centerOfGestureDetector = Offset(
                          constraints.maxWidth / 2, constraints.maxHeight / 2);
                      final touchPositionFromCenter =
                          details.localPosition - centerOfGestureDetector;
                      setState(() {
                        finalAngle =
                            touchPositionFromCenter.direction - offsetAngle;
                      });
                    },
                    child: Transform.rotate(
                      angle: finalAngle,
                      child: Icon(
                        Icons.settings,
                        color: Colors.white,
                        size: 200.0,
                      ),
                    ),
                  );
                },
              ),
            )
          ],
        ),
      ),
    );
  }
}

1. Widget moves when tap to rotate button in some unknown angle. Why? 2. It is too sensitive to gesture. So, can we make more smooth? Please help me with this. — jazzbpn, Jun 17 '21 at 02:15
The first example is rotates based on you finger position from center point. you can try the second example — Crazy Lazy Cat, Jun 18 '21 at 03:22

Rotate text or image using button gesture in flutter

1 Answers1

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