mirror of
https://github.com/flutter/flutter
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1b9476c4d9
The 'routes' table is a point of confusion with new developers. By providing a 'home' argument that sets the '/' route, we can delay the point at which we teach developers about 'routes' until the point where they want to have a second route.
227 lines
7.1 KiB
Dart
227 lines
7.1 KiB
Dart
// Copyright 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'package:flutter/material.dart';
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class _GesturePainter extends CustomPainter {
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const _GesturePainter({
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this.zoom,
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this.offset,
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this.swatch,
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this.forward,
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this.scaleEnabled,
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this.tapEnabled,
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this.doubleTapEnabled,
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this.longPressEnabled
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});
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final double zoom;
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final Offset offset;
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final Map<int, Color> swatch;
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final bool forward;
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final bool scaleEnabled;
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final bool tapEnabled;
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final bool doubleTapEnabled;
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final bool longPressEnabled;
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@override
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void paint(Canvas canvas, Size size) {
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Point center = (size.center(Point.origin).toOffset() * zoom + offset).toPoint();
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double radius = size.width / 2.0 * zoom;
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Gradient gradient = new RadialGradient(
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colors: forward ? <Color>[swatch[50], swatch[900]]
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: <Color>[swatch[900], swatch[50]]
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);
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Paint paint = new Paint()
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..shader = gradient.createShader(new Rect.fromLTWH(
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center.x - radius,
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center.y - radius,
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radius * 2.0,
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radius * 2.0
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));
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canvas.drawCircle(center, radius, paint);
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}
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@override
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bool shouldRepaint(_GesturePainter oldPainter) {
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return oldPainter.zoom != zoom
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|| oldPainter.offset != offset
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|| oldPainter.swatch != swatch
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|| oldPainter.forward != forward
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|| oldPainter.scaleEnabled != scaleEnabled
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|| oldPainter.tapEnabled != tapEnabled
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|| oldPainter.doubleTapEnabled != doubleTapEnabled
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|| oldPainter.longPressEnabled != longPressEnabled;
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}
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}
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class GestureDemo extends StatefulWidget {
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@override
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_GestureDemoState createState() => new _GestureDemoState();
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}
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class _GestureDemoState extends State<GestureDemo> {
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Point _startingFocalPoint;
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Offset _previousOffset;
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Offset _offset = Offset.zero;
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double _previousZoom;
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double _zoom = 1.0;
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Map<int, Color> _swatch = Colors.blue;
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bool _forward = true;
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bool _scaleEnabled = true;
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bool _tapEnabled = true;
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bool _doubleTapEnabled = true;
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bool _longPressEnabled = true;
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void _handleScaleStart(Point focalPoint) {
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setState(() {
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_startingFocalPoint = focalPoint;
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_previousOffset = _offset;
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_previousZoom = _zoom;
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});
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}
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void _handleScaleUpdate(double scale, Point focalPoint) {
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setState(() {
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_zoom = (_previousZoom * scale);
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// Ensure that item under the focal point stays in the same place despite zooming
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Offset normalizedOffset = (_startingFocalPoint.toOffset() - _previousOffset) / _previousZoom;
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_offset = focalPoint.toOffset() - normalizedOffset * _zoom;
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});
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}
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void _handleScaleReset() {
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setState(() {
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_zoom = 1.0;
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_offset = Offset.zero;
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});
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}
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void _handleColorChange() {
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setState(() {
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switch (_swatch) {
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case Colors.blueGrey: _swatch = Colors.red; break;
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case Colors.red: _swatch = Colors.pink; break;
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case Colors.pink: _swatch = Colors.purple; break;
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case Colors.purple: _swatch = Colors.deepPurple; break;
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case Colors.deepPurple: _swatch = Colors.indigo; break;
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case Colors.indigo: _swatch = Colors.blue; break;
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case Colors.blue: _swatch = Colors.lightBlue; break;
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case Colors.lightBlue: _swatch = Colors.cyan; break;
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case Colors.cyan: _swatch = Colors.teal; break;
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case Colors.teal: _swatch = Colors.green; break;
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case Colors.green: _swatch = Colors.lightGreen; break;
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case Colors.lightGreen: _swatch = Colors.lime; break;
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case Colors.lime: _swatch = Colors.yellow; break;
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case Colors.yellow: _swatch = Colors.amber; break;
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case Colors.amber: _swatch = Colors.orange; break;
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case Colors.orange: _swatch = Colors.deepOrange; break;
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case Colors.deepOrange: _swatch = Colors.brown; break;
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case Colors.brown: _swatch = Colors.grey; break;
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case Colors.grey: _swatch = Colors.blueGrey; break;
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default: assert(false);
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}
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});
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}
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void _handleDirectionChange() {
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setState(() {
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_forward = !_forward;
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});
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}
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@override
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Widget build(BuildContext context) {
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return new Stack(
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children: <Widget>[
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new GestureDetector(
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onScaleStart: _scaleEnabled ? _handleScaleStart : null,
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onScaleUpdate: _scaleEnabled ? _handleScaleUpdate : null,
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onTap: _tapEnabled ? _handleColorChange : null,
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onDoubleTap: _doubleTapEnabled ? _handleScaleReset : null,
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onLongPress: _longPressEnabled ? _handleDirectionChange : null,
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child: new CustomPaint(
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painter: new _GesturePainter(
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zoom: _zoom,
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offset: _offset,
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swatch: _swatch,
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forward: _forward,
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scaleEnabled: _scaleEnabled,
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tapEnabled: _tapEnabled,
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doubleTapEnabled: _doubleTapEnabled,
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longPressEnabled: _longPressEnabled
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)
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)
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),
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new Positioned(
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bottom: 0.0,
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left: 0.0,
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child: new Card(
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child: new Container(
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padding: new EdgeInsets.all(4.0),
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child: new Column(
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children: <Widget>[
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new Row(
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children: <Widget>[
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new Checkbox(
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value: _scaleEnabled,
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onChanged: (bool value) { setState(() { _scaleEnabled = value; }); }
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),
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new Text('Scale'),
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]
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),
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new Row(
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children: <Widget>[
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new Checkbox(
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value: _tapEnabled,
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onChanged: (bool value) { setState(() { _tapEnabled = value; }); }
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),
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new Text('Tap'),
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]
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),
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new Row(
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children: <Widget>[
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new Checkbox(
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value: _doubleTapEnabled,
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onChanged: (bool value) { setState(() { _doubleTapEnabled = value; }); }
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),
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new Text('Double Tap'),
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]
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),
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new Row(
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children: <Widget>[
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new Checkbox(
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value: _longPressEnabled,
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onChanged: (bool value) { setState(() { _longPressEnabled = value; }); }
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),
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new Text('Long Press'),
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]
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),
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],
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crossAxisAlignment: CrossAxisAlignment.start
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)
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)
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)
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),
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]
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);
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}
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}
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void main() {
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runApp(new MaterialApp(
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theme: new ThemeData.dark(),
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home: new Scaffold(
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appBar: new AppBar(title: new Text('Gestures Demo')),
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body: new GestureDemo()
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)
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));
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}
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