// Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. // Template: dev/snippets/config/templates/stateful_widget_material.tmpl // // Comment lines marked with "▼▼▼" and "▲▲▲" are used for authoring // of samples, and may be ignored if you are just exploring the sample. // Flutter code sample for PointerSignalResolver // //*************************************************************************** //* ▼▼▼▼▼▼▼▼ description ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) // Here is an example that demonstrates the effect of not using the resolver // versus using it. // // When this example is set to _not_ use the resolver, then triggering the // mouse wheel over the outer box will cause only the outer box to change // color, but triggering the mouse wheel over the inner box will cause _both_ // the outer and the inner boxes to change color (because they're both // receiving the event). // // When this example is set to _use_ the resolver, then only the box located // directly under the cursor will change color when the mouse wheel is // triggered. //* ▲▲▲▲▲▲▲▲ description ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) //*************************************************************************** //**************************************************************************** //* ▼▼▼▼▼▼▼▼ code-imports ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) import 'package:flutter/gestures.dart'; //* ▲▲▲▲▲▲▲▲ code-imports ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) //**************************************************************************** import 'package:flutter/material.dart'; void main() => runApp(const MyApp()); /// This is the main application widget. class MyApp extends StatelessWidget { const MyApp({Key? key}) : super(key: key); static const String _title = 'Flutter Code Sample'; @override Widget build(BuildContext context) { return const MaterialApp( title: _title, home: MyStatefulWidget(), ); } } //***************************************************************************** //* ▼▼▼▼▼▼▼▼ code-preamble ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) class ColorChanger extends StatefulWidget { const ColorChanger({ Key? key, required this.initialColor, required this.useResolver, this.child, }) : super(key: key); final HSVColor initialColor; final bool useResolver; final Widget? child; @override State<ColorChanger> createState() => _ColorChangerState(); } class _ColorChangerState extends State<ColorChanger> { late HSVColor color; void rotateColor() { setState(() { color = color.withHue((color.hue + 3) % 360.0); }); } @override void initState() { super.initState(); color = widget.initialColor; } @override Widget build(BuildContext context) { return DecoratedBox( decoration: BoxDecoration( border: const Border.fromBorderSide(BorderSide()), color: color.toColor(), ), child: Listener( onPointerSignal: (PointerSignalEvent event) { if (widget.useResolver) { GestureBinding.instance!.pointerSignalResolver.register(event, (PointerSignalEvent event) { rotateColor(); }); } else { rotateColor(); } }, child: Stack( fit: StackFit.expand, children: <Widget>[ const AbsorbPointer(), if (widget.child != null) widget.child!, ], ), ), ); } } //* ▲▲▲▲▲▲▲▲ code-preamble ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) //***************************************************************************** /// This is the stateful widget that the main application instantiates. class MyStatefulWidget extends StatefulWidget { const MyStatefulWidget({Key? key}) : super(key: key); @override State<MyStatefulWidget> createState() => _MyStatefulWidgetState(); } /// This is the private State class that goes with MyStatefulWidget. class _MyStatefulWidgetState extends State<MyStatefulWidget> { //******************************************************************** //* ▼▼▼▼▼▼▼▼ code ▼▼▼▼▼▼▼▼ (do not modify or remove section marker) bool useResolver = false; @override Widget build(BuildContext context) { return Material( child: Stack( fit: StackFit.expand, children: <Widget>[ ColorChanger( initialColor: const HSVColor.fromAHSV(0.2, 120.0, 1, 1), useResolver: useResolver, child: FractionallySizedBox( widthFactor: 0.5, heightFactor: 0.5, child: ColorChanger( initialColor: const HSVColor.fromAHSV(1, 60.0, 1, 1), useResolver: useResolver, ), ), ), Align( alignment: Alignment.topLeft, child: Row( crossAxisAlignment: CrossAxisAlignment.center, children: <Widget>[ Switch( value: useResolver, onChanged: (bool value) { setState(() { useResolver = value; }); }, ), const Text( 'Use the PointerSignalResolver?', style: TextStyle(fontWeight: FontWeight.bold), ), ], ), ), ], ), ); } //* ▲▲▲▲▲▲▲▲ code ▲▲▲▲▲▲▲▲ (do not modify or remove section marker) //******************************************************************** }