brianegan

import 'package:flutter/cupertino.dart';

class UndoChangeNotifier<T> extends ChangeNotifier {
  List<T> _history;
  int _historyIndex;

  UndoChangeNotifier([T initialState]) {
    _history = initialState != null ? [initialState] : [];
    _historyIndex = initialState != null ? 0 : -1;
  }

brianegan

import 'package:flutter/cupertino.dart';

class UndoChangeNotifier<T> extends ChangeNotifier {
  final List<T> _history;
  int _historyIndex = -1;

  UndoChangeNotifier(T initialState) : _history = [initialState];

  T get state => hasState ? _history[_historyIndex] : null;

brianegan

import 'dart:math' show pi;

import 'package:flutter/material.dart';

void main() => runApp(SpinniesApp());

class SpinniesApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(

brianegan

import 'dart:math' show pi;

import 'package:flutter/material.dart';

void main() => runApp(SpinniesApp());

class SpinniesApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(

brianegan

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final appTitle = 'Opacity Demo';
    return MaterialApp(
      title: appTitle,

brianegan

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {

brianegan

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final appTitle = 'Orientation Demo';

brianegan

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  final appTitle = 'Drawer Demo';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(

brianegan

import 'package:flutter/material.dart';
import 'package:flutter/physics.dart';

main() {
  runApp(MaterialApp(home: PhysicsCardDragDemo()));
}

class PhysicsCardDragDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {

brianegan

import 'package:flutter/material.dart';

main() {
  runApp(MaterialApp(
    home: Page1(),
  ));
}

class Page1 extends StatelessWidget {
  Widget build(BuildContext context) {