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Hi, yesterday I found this package while building my hackathon project and it didn't work. I tried wrapping a couple of different widgets to check if it works or not.

Today I scaffolded a new project, the famous counter app, and tried wrapping MyHomePage in Snappable widget and it still doesn't work.

Am I missing something? Could you please help me? Thanks.

Example

import 'package:flutter/material.dart';
import 'package:snappable/snappable.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
        // This makes the visual density adapt to the platform that you run
        // the app on. For desktop platforms, the controls will be smaller and
        // closer together (more dense) than on mobile platforms.
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: Snappable(child: MyHomePage(title: 'Flutter Demo Home Page')),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

Doctor

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 1.20.4, on Linux, locale en_IN)
 
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
[✓] Android Studio (version 4.0)
[✓] IntelliJ IDEA Ultimate Edition (version 2019.3)
[✓] VS Code (version 1.49.1)
[✓] Connected device (1 available)

• No issues found!

Version 1.0.1.

Non-fatal Exception: NoSuchMethodError: The method 'findRenderObject' was called on null.
Receiver: null
Tried calling: findRenderObject()
0  ???                            0x0 _getImageFromWidget + 232 (snappable.dart:232)
1  ???                            0x0 snap + 114 (snappable.dart:114)

Probably it was called after parent widget was disposed.

snappable: 1.0.1

Non-fatal Exception: NoSuchMethodError: The method 'markNeedsBuild' was called on null.
Receiver: null
Tried calling: markNeedsBuild()
0  ???                            0x0 setState + 1168 (framework.dart:1168)
1  ???                            0x0 snap + 150 (snappable.dart:150)

Set state called on unmouted widget. Possible fix: add mounted check before setState

Hi, I'm receiving this error on our production application. Our usage is not good enough, I just spotted it, we are using timer to delay some action then call snap method. We are using delays, but also there is delay in the snap method itself. Before calling _animationController.forward(); you should check if controller is not null and widget is mounted. snappable: 1.0.1, error:

Non-fatal Exception: NoSuchMethodError: The method 'stop' was called on null.
Receiver: null
Tried calling: stop()
0  ???                            0x0 stop + 738 (animation_controller.dart:738)
1  ???                            0x0 _animateToInternal + 576 (animation_controller.dart:576)
2  ???                            0x0 forward + 458 (animation_controller.dart:458)
3  ???                            0x0 snap + 161 (snappable.dart:161)

Platform Web

Log: org-dartlang-sdk:///flutter_web_sdk/lib/_engine/engine/surface/scene_builder.dart:227:12 retainedSurface.isActive || retainedSurface.isReleased is not true