mirror of
https://github.com/flutter/flutter
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55289324c6
Adds MediaQuery.maybeOf to replace calling MediaQuery.of(context, nullOk: true), and removes the nullOk parameter. Also changes MediaQuery.of to return a non-nullable value, and removes many instances of the ! operator, reducing the possible places where a null dereference could occur.
103 lines
2.6 KiB
Dart
103 lines
2.6 KiB
Dart
// Copyright 2014 The Flutter 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 AdaptedListItem extends StatelessWidget {
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const AdaptedListItem({ Key? key, required this.name }) : super(key: key);
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final String name;
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@override
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Widget build(BuildContext context) {
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return Row(
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children: <Widget>[
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Container(
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width: 32.0,
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height: 32.0,
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margin: const EdgeInsets.all(8.0),
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color: Colors.lightBlueAccent.shade100,
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),
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Text(name),
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],
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);
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}
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}
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class AdaptedGridItem extends StatelessWidget {
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const AdaptedGridItem({ Key? key, required this.name }) : super(key: key);
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final String name;
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@override
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Widget build(BuildContext context) {
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return Card(
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child: Column(
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children: <Widget>[
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Expanded(
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child: Container(
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color: Colors.lightBlueAccent.shade100,
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),
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),
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Container(
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margin: const EdgeInsets.only(left: 8.0),
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child: Row(
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children: <Widget>[
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Expanded(
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child: Text(name),
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),
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const IconButton(
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icon: Icon(Icons.more_vert),
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onPressed: null,
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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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}
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const double _kListItemExtent = 50.0;
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const double _kMaxTileWidth = 150.0;
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const double _kGridViewBreakpoint = 450.0;
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class AdaptiveContainer extends StatelessWidget {
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const AdaptiveContainer({ Key? key, required this.names }) : super(key: key);
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final List<String> names;
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@override
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Widget build(BuildContext context) {
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if (MediaQuery.of(context).size.width < _kGridViewBreakpoint) {
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return ListView(
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itemExtent: _kListItemExtent,
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children: names.map<Widget>((String name) => AdaptedListItem(name: name)).toList(),
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);
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} else {
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return GridView.extent(
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maxCrossAxisExtent: _kMaxTileWidth,
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children: names.map<Widget>((String name) => AdaptedGridItem(name: name)).toList(),
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);
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}
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}
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}
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List<String> _initNames() => List<String>.generate(30, (int i) => 'Item $i');
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final List<String> _kNames = _initNames();
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void main() {
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runApp(MaterialApp(
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title: 'Media Query Example',
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home: Scaffold(
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appBar: AppBar(
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title: const Text('Media Query Example'),
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),
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body: Material(child: AdaptiveContainer(names: _kNames)),
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),
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));
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}
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