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I/flutter : ══╡ EXCEPTION CAUGHT BY GESTURE LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter : The following assertion was thrown while routing a pointer event:
I/flutter : 'package:flutter/src/physics/friction_simulation.dart': Failed assertion: line 40 pos 12:
I/flutter : 'startVelocity.abs() >= endVelocity.abs()' is not true.
I/flutter : When the exception was thrown, this was the stack:
I/flutter : #2      FrictionSimulation.FrictionSimulation.through (package:flutter/src/physics/friction_simulation.dart:40:12)
I/flutter : #3      _createSnapScrollSimulation (package:flutter/src/widgets/scroll_behavior.dart:16:14)
I/flutter : #4      OverscrollBehavior.createSnapScrollSimulation (package:flutter/src/widgets/scroll_behavior.dart:257:12)
I/flutter : #5      ScrollableState._createSnapSimulation (package:flutter/src/widgets/scrollable.dart:622:50)
I/flutter : #6      ScrollableState._startToEndAnimation (package:flutter/src/widgets/scrollable.dart:587:19)
I/flutter : #7      ScrollableState.fling (package:flutter/src/widgets/scrollable.dart:564:14)

class AnimationDemo extends StatefulWidget {
  static const String routeName = '/animation';

  @override
  AnimationDemoState createState() => new AnimationDemoState();
}

class AnimationDemoState extends State<AnimationDemo> {
  final GlobalKey<ScrollableState> _scrollableKey = new GlobalKey<ScrollableState>();
  final List<Color> colors = [
    Colors.red[100],
    Colors.red[200],
    Colors.red[300],
    Colors.red[400],
    Colors.red[500],
    Colors.red[600],
  ];

  Widget _createPage(int i) {
    final double pageWidth = MediaQuery.of(context).size.width;
    return new Container(
      decoration: new BoxDecoration(
        backgroundColor: colors[i]
      ),
      child: new SizedBox(
        width: pageWidth,
        child: new Center(
          child: new Text('Page $i'),
        ),
      ),
    );
  }

  double _snapScrollOffset(double flingScrollOffset, Size containerSize) {
    return flingScrollOffset;
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('Travel stream'),
      ),
      body: new ScrollableViewport(
        scrollableKey: _scrollableKey,
        scrollDirection: Axis.horizontal,
        snapOffsetCallback: _snapScrollOffset,
        child: new Row(
          children: [0, 1, 2, 3, 4, 5].map(_createPage).toList(),
        ),
      ),
    );
  }
}