Demonstrates Padding vs ViewPadding vs ViewInsets

mediaquerydata-demo.dart

// Copyright 2013 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.

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    final originalTheme = Theme.of(context);
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Theme(
          data: originalTheme.copyWith(
            textTheme: originalTheme.textTheme.copyWith(
              bodyMedium: originalTheme.textTheme.bodyMedium!.copyWith(
                fontSize: 16,
              ),
            ),
          ),
          child: const MyHomePage(title: 'Flutter Demo Home Page')),
    );
  }
}

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

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      resizeToAvoidBottomInset: false,
      body: Stack(
        children: const <Widget>[
          FullStack(),
        ],
      ),
    );
  }
}

class FullStack extends StatefulWidget {
  const FullStack({Key? key}) : super(key: key);

  @override
  State<FullStack> createState() => _FullStackState();
}

class _FullStackState extends State<FullStack> {
  bool _safeArea = true;
  bool _fakeKeyboard = false;

  final focusNode = FocusNode();

  @override
  void initState() {
    super.initState();
    focusNode.requestFocus();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        // Uncomment this if you want to summon the real keyboard on mobile.
        // const SizedBox(height: 100),
        // Padding(
        //   padding: const EdgeInsets.symmetric(horizontal: 12),
        //   child: Row(
        //     children: <Widget>[
        //       Expanded(
        //         child: TextField(
        //           decoration: InputDecoration(
        //             filled: true,
        //             fillColor: Colors.grey[300],
        //           ),
        //         ),
        //       ),
        //     ],
        //   ),
        // ),
        Flexible(
          child: LayoutBuilder(
            builder: (BuildContext context, BoxConstraints constraints) {
              final keyboardTextStyle = Theme.of(context).textTheme.displayMedium;
              late final EdgeInsets viewPadding;
              late final EdgeInsets padding;

              late final EdgeInsets positioning;

              if (!_safeArea && !_fakeKeyboard) {
                viewPadding = const EdgeInsets.symmetric(vertical: 20);
                padding = const EdgeInsets.symmetric(vertical: 20);
                positioning = EdgeInsets.zero;
              } else if (_safeArea && !_fakeKeyboard) {
                viewPadding = EdgeInsets.zero;
                padding = EdgeInsets.zero;
                positioning = const EdgeInsets.symmetric(vertical: 20);
              } else if (!_safeArea && _fakeKeyboard) {
                viewPadding = const EdgeInsets.symmetric(vertical: 20);
                padding = const EdgeInsets.fromLTRB(0, 20, 0, 0);
                positioning = EdgeInsets.zero;
              } else {
                // Have both
                viewPadding = const EdgeInsets.fromLTRB(0, 0, 0, 20);
                padding = EdgeInsets.zero;
                positioning = const EdgeInsets.only(top: 20);
              }

              final MediaQueryData mq = MediaQuery.of(context).copyWith(
                padding: padding,
                viewPadding: viewPadding,
                viewInsets: EdgeInsets.fromLTRB(
                  0,
                  0,
                  0,
                  _fakeKeyboard ? 300 : 0,
                ),
              );
              return Stack(
                children: <Widget>[
                  // Top notch (heh)
                  Positioned(
                    left: mq.size.width / 4,
                    top: 10,
                    child: Container(
                      height: 5,
                      width: mq.size.width / 2,
                      color: Colors.grey[800],
                    ),
                  ),
                  // Bottom notch
                  !_fakeKeyboard
                      ? Positioned(
                          left: mq.size.width / 4,
                          bottom: 10,
                          child: Container(
                            height: 5,
                            width: mq.size.width / 2,
                            color: Colors.grey[800],
                          ),
                        )
                      : Container(),
                  Positioned(
                    bottom: mq.size.height / 2,
                    left: mq.size.width / 2.5,
                    child: Column(
                      children: <Widget>[
                        Text(
                          'Fake keyboard is ${_fakeKeyboard ? "REVEALED" : "HIDDEN"}',
                          style: Theme.of(context).textTheme.headlineSmall,
                        ),
                        Switch(
                          value: _fakeKeyboard,
                          onChanged: (value) {
                            setState(() {
                              _fakeKeyboard = value;
                            });
                          },
                        ),
                        Text(
                          'SafeArea is ${_safeArea ? "ON" : "OFF"}',
                          style: Theme.of(context).textTheme.headlineSmall,
                        ),
                        Switch(
                          value: _safeArea,
                          onChanged: (value) {
                            setState(() {
                              _safeArea = value;
                            });
                          },
                        ),
                      ],
                    ),
                  ),
                  Positioned(
                    top: positioning.top,
                    left: mq.size.width / 2.2,
                    child: MediaQueryTopInfo(mediaQueryData: mq),
                  ),
                  Positioned(
                    top: mq.size.height / 2.5 - mq.viewInsets.bottom / 2,
                    left: positioning.left,
                    child: MediaQueryLeftInfo(mediaQueryData: mq),
                  ),
                  Positioned(
                    top: mq.size.height / 2.5 - mq.viewInsets.bottom / 2,
                    right: positioning.right,
                    child: MediaQueryRightInfo(mediaQueryData: mq),
                  ),
                  Positioned(
                    bottom: positioning.bottom + mq.viewInsets.bottom,
                    left: mq.size.width / 2.2,
                    child: MediaQueryBottomInfo(mediaQueryData: mq),
                  ),
                  _fakeKeyboard
                      ? Positioned(
                          bottom: 0,
                          width: mq.size.width,
                          height: 300,
                          child: Container(
                            color: Colors.grey[300],
                            child: Row(
                              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                              children: <Widget>[
                                Text('K', style: keyboardTextStyle),
                                Text('E', style: keyboardTextStyle),
                                Text('Y', style: keyboardTextStyle),
                                Text('B', style: keyboardTextStyle),
                                Text('O', style: keyboardTextStyle),
                                Text('A', style: keyboardTextStyle),
                                Text('R', style: keyboardTextStyle),
                                Text('D', style: keyboardTextStyle),
                              ],
                            ),
                          ),
                        )
                      : Container()
                ],
              );
            },
          ),
        )
      ],
    );
  }
}

class MediaQueryBottomInfo extends StatelessWidget {
  const MediaQueryBottomInfo({Key? key, required this.mediaQueryData})
      : super(key: key);

  final MediaQueryData mediaQueryData;

  @override
  Widget build(BuildContext context) {
    final viewInsets = mediaQueryData.viewInsets;
    final viewPadding = mediaQueryData.viewPadding;
    final padding = mediaQueryData.padding;
    return Column(
      children: <Widget>[
        const Text('BOTTOM'),
        Text('Padding: ${padding.bottom}'),
        Text('ViewPadding: ${viewPadding.bottom}'),
        Text('ViewInsets: ${viewInsets.bottom}'),
      ],
    );
  }
}

class MediaQueryTopInfo extends StatelessWidget {
  const MediaQueryTopInfo({Key? key, required this.mediaQueryData})
      : super(key: key);

  final MediaQueryData mediaQueryData;

  @override
  Widget build(BuildContext context) {
    final viewInsets = mediaQueryData.viewInsets;
    final viewPadding = mediaQueryData.viewPadding;
    final padding = mediaQueryData.padding;
    return Column(
      children: <Widget>[
        const Text('TOP'),
        Text('Padding: ${padding.top}'),
        Text('ViewPadding: ${viewPadding.top}'),
        Text('ViewInsets: ${viewInsets.top}'),
      ],
    );
  }
}

class MediaQueryLeftInfo extends StatelessWidget {
  const MediaQueryLeftInfo({Key? key, required this.mediaQueryData})
      : super(key: key);

  final MediaQueryData mediaQueryData;

  @override
  Widget build(BuildContext context) {
    final viewInsets = mediaQueryData.viewInsets;
    final viewPadding = mediaQueryData.viewPadding;
    final padding = mediaQueryData.padding;
    return Column(
      children: <Widget>[
        const Text('LEFT'),
        Text('Padding: ${padding.left}'),
        Text('ViewPadding: ${viewPadding.left}'),
        Text('ViewInsets: ${viewInsets.left}'),
      ],
    );
  }
}

class MediaQueryRightInfo extends StatelessWidget {
  const MediaQueryRightInfo({Key? key, required this.mediaQueryData})
      : super(key: key);

  final MediaQueryData mediaQueryData;

  @override
  Widget build(BuildContext context) {
    final viewInsets = mediaQueryData.viewInsets;
    final viewPadding = mediaQueryData.viewPadding;
    final padding = mediaQueryData.padding;
    return Column(
      children: <Widget>[
        const Text('RIGHT'),
        Text('Padding: ${padding.right}'),
        Text('ViewPadding: ${viewPadding.right}'),
        Text('ViewInsets: ${viewInsets.right}'),
      ],
    );
  }
}