samples/gallery/lib/studies/rally/login.dart

// Copyright 2019 The Flutter team. 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';
import 'package:flutter/services.dart';
import 'package:gallery/data/gallery_options.dart';
import 'package:gallery/l10n/gallery_localizations.dart';
import 'package:gallery/layout/adaptive.dart';
import 'package:gallery/layout/text_scale.dart';
import 'package:gallery/pages/home.dart';
import 'package:gallery/studies/rally/colors.dart';
import 'package:gallery/layout/focus_traversal_policy.dart';

class LoginPage extends StatefulWidget {
  @override
  _LoginPageState createState() => _LoginPageState();
}

class _LoginPageState extends State<LoginPage> {
  final TextEditingController _usernameController = TextEditingController();
  final TextEditingController _passwordController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    final backButtonFocusNode =
        InheritedFocusNodes.of(context).backButtonFocusNode;

    return DefaultFocusTraversal(
      policy: EdgeChildrenFocusTraversalPolicy(
        firstFocusNodeOutsideScope: backButtonFocusNode,
        lastFocusNodeOutsideScope: backButtonFocusNode,
        focusScope: FocusScope.of(context),
      ),
      child: ApplyTextOptions(
        child: Scaffold(
          body: SafeArea(
            child: _MainView(
              usernameController: _usernameController,
              passwordController: _passwordController,
            ),
          ),
        ),
      ),
    );
  }

  @override
  void dispose() {
    _usernameController.dispose();
    _passwordController.dispose();
    super.dispose();
  }
}

class _MainView extends StatelessWidget {
  const _MainView({
    Key key,
    this.usernameController,
    this.passwordController,
  }) : super(key: key);

  final TextEditingController usernameController;
  final TextEditingController passwordController;

  void _login(BuildContext context) {
    Navigator.pop(context);
  }

  @override
  Widget build(BuildContext context) {
    final isDesktop = isDisplayDesktop(context);
    List<Widget> listViewChildren;

    if (isDesktop) {
      final desktopMaxWidth = 400.0 + 100.0 * (cappedTextScale(context) - 1);
      listViewChildren = [
        _UsernameInput(
          maxWidth: desktopMaxWidth,
          usernameController: usernameController,
        ),
        const SizedBox(height: 12),
        _PasswordInput(
          maxWidth: desktopMaxWidth,
          passwordController: passwordController,
        ),
        _LoginButton(
          maxWidth: desktopMaxWidth,
          onTap: () {
            _login(context);
          },
        ),
      ];
    } else {
      listViewChildren = [
        _SmallLogo(),
        _UsernameInput(
          usernameController: usernameController,
        ),
        const SizedBox(height: 12),
        _PasswordInput(
          passwordController: passwordController,
        ),
        _ThumbButton(
          onTap: () {
            _login(context);
          },
        ),
      ];
    }

    return Column(
      children: [
        if (isDesktop) _TopBar(),
        Expanded(
          child: Align(
            alignment: isDesktop ? Alignment.center : Alignment.topCenter,
            child: ListView(
              shrinkWrap: true,
              padding: const EdgeInsets.symmetric(horizontal: 24),
              children: listViewChildren,
            ),
          ),
        ),
      ],
    );
  }
}

class _TopBar extends StatelessWidget {
  const _TopBar({
    Key key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final spacing = const SizedBox(width: 30);
    return Container(
      width: double.infinity,
      margin: const EdgeInsets.only(top: 8),
      padding: EdgeInsets.symmetric(horizontal: 30),
      child: Wrap(
        alignment: WrapAlignment.spaceBetween,
        children: [
          Row(
            mainAxisSize: MainAxisSize.min,
            children: [
              ExcludeSemantics(
                child: SizedBox(
                  height: 80,
                  child: Image.asset(
                    'logo.png',
                    package: 'rally_assets',
                  ),
                ),
              ),
              spacing,
              Text(
                GalleryLocalizations.of(context).rallyLoginLoginToRally,
                style: Theme.of(context).textTheme.body2.copyWith(
                      fontSize: 35 / reducedTextScale(context),
                      fontWeight: FontWeight.w600,
                    ),
              ),
            ],
          ),
          Row(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text(
                GalleryLocalizations.of(context).rallyLoginNoAccount,
                style: Theme.of(context).textTheme.subhead,
              ),
              spacing,
              _BorderButton(
                text: GalleryLocalizations.of(context).rallyLoginSignUp,
              ),
            ],
          ),
        ],
      ),
    );
  }
}

class _SmallLogo extends StatelessWidget {
  const _SmallLogo({
    Key key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.symmetric(vertical: 64),
      child: SizedBox(
        height: 160,
        child: ExcludeSemantics(
          child: Image.asset(
            'logo.png',
            package: 'rally_assets',
          ),
        ),
      ),
    );
  }
}

class _UsernameInput extends StatelessWidget {
  const _UsernameInput({
    Key key,
    this.maxWidth,
    this.usernameController,
  }) : super(key: key);

  final double maxWidth;
  final TextEditingController usernameController;

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: Alignment.center,
      child: Container(
        constraints: BoxConstraints(maxWidth: maxWidth ?? double.infinity),
        child: TextField(
          controller: usernameController,
          decoration: InputDecoration(
            labelText: GalleryLocalizations.of(context).rallyLoginUsername,
          ),
        ),
      ),
    );
  }
}

class _PasswordInput extends StatelessWidget {
  const _PasswordInput({
    Key key,
    this.maxWidth,
    this.passwordController,
  }) : super(key: key);

  final double maxWidth;
  final TextEditingController passwordController;

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: Alignment.center,
      child: Container(
        constraints: BoxConstraints(maxWidth: maxWidth ?? double.infinity),
        child: TextField(
          controller: passwordController,
          decoration: InputDecoration(
            labelText: GalleryLocalizations.of(context).rallyLoginPassword,
          ),
          obscureText: true,
        ),
      ),
    );
  }
}

class _ThumbButton extends StatefulWidget {
  _ThumbButton({
    @required this.onTap,
  });

  final VoidCallback onTap;

  @override
  _ThumbButtonState createState() => _ThumbButtonState();
}

class _ThumbButtonState extends State<_ThumbButton> {
  BoxDecoration borderDecoration;

  @override
  Widget build(BuildContext context) {
    return Semantics(
      button: true,
      enabled: true,
      label: GalleryLocalizations.of(context).rallyLoginLabelLogin,
      child: GestureDetector(
        onTap: widget.onTap,
        child: Focus(
          onKey: (node, event) {
            if (event is RawKeyDownEvent) {
              if (event.logicalKey == LogicalKeyboardKey.enter ||
                  event.logicalKey == LogicalKeyboardKey.space) {
                widget.onTap();
                return true;
              }
            }
            return false;
          },
          onFocusChange: (hasFocus) {
            if (hasFocus) {
              setState(() {
                borderDecoration = BoxDecoration(
                  border: Border.all(
                    color: Colors.white.withOpacity(0.5),
                    width: 2,
                  ),
                );
              });
            } else {
              setState(() {
                borderDecoration = null;
              });
            }
          },
          child: Container(
            decoration: borderDecoration,
            height: 120,
            child: ExcludeSemantics(
              child: Image.asset(
                'thumb.png',
                package: 'rally_assets',
              ),
            ),
          ),
        ),
      ),
    );
  }
}

class _LoginButton extends StatelessWidget {
  const _LoginButton({
    Key key,
    @required this.onTap,
    this.maxWidth,
  }) : super(key: key);

  final double maxWidth;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    return Align(
      alignment: Alignment.center,
      child: Container(
        constraints: BoxConstraints(maxWidth: maxWidth ?? double.infinity),
        padding: const EdgeInsets.symmetric(vertical: 30),
        child: Row(
          children: [
            Icon(Icons.check_circle_outline, color: RallyColors.buttonColor),
            const SizedBox(width: 12),
            Text(GalleryLocalizations.of(context).rallyLoginRememberMe),
            const Expanded(child: SizedBox.shrink()),
            _FilledButton(
              text: GalleryLocalizations.of(context).rallyLoginButtonLogin,
              onTap: onTap,
            ),
          ],
        ),
      ),
    );
  }
}

class _BorderButton extends StatelessWidget {
  const _BorderButton({Key key, @required this.text}) : super(key: key);

  final String text;

  @override
  Widget build(BuildContext context) {
    return OutlineButton(
      borderSide: const BorderSide(color: RallyColors.buttonColor),
      color: RallyColors.buttonColor,
      highlightedBorderColor: RallyColors.buttonColor,
      focusColor: RallyColors.buttonColor.withOpacity(0.8),
      padding: const EdgeInsets.symmetric(vertical: 14, horizontal: 24),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(12),
      ),
      textColor: Colors.white,
      onPressed: () {
        Navigator.pop(context);
      },
      child: Text(text),
    );
  }
}

class _FilledButton extends StatelessWidget {
  const _FilledButton({Key key, @required this.text, @required this.onTap})
      : super(key: key);

  final String text;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    return FlatButton(
      color: RallyColors.buttonColor,
      padding: const EdgeInsets.symmetric(vertical: 10, horizontal: 24),
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(12),
      ),
      onPressed: onTap,
      child: Row(
        children: [
          Icon(Icons.lock),
          const SizedBox(width: 6),
          Text(text),
        ],
      ),
    );
  }
}