[work in progress] Add memento editor example.

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 0.18.0
+- Add Memento Editor.
+
 ## 0.17.16 - refactoring
 - Simplifying the ternary construction.
 - Remove multiline comment from main README.

README.md

@@ -15,7 +15,7 @@ It contains **Dart** examples for all classic **GoF** design patterns.
     - [ ] Interpreter
     - [ ] **Iterator**
     - [ ] **Mediator**
-    - [x] **Memento** - [[Conceptual](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/memento/conceptual)]
+    - [x] **Memento** - [[Conceptual](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/memento/conceptual)] [[Memento Editor](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/memento/memento_editor)] 
     - [x] **Observer** - [[Open-Close Editor Events](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/observer/open_close_editor_events)] [[AppObserver](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/observer/app_observer)] [[Subscriber Flutter Widget](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/observer/subscriber_flutter_widget)]
     - [ ] **State**
     - [ ] **Template Method**
@@ -33,7 +33,7 @@ It contains **Dart** examples for all classic **GoF** design patterns.
 ## Requirements
 
 The examples were written in **Dart 2.15**.
-Some complex examples require **Flutter 2.15.0**.
+Some complex examples require **Flutter 2.12**.
 
 ## Contributor's Guide
 

bin/deploy_flutter_demos.dart

@@ -119,7 +119,7 @@ Future<String> repositoryOriginUrl(Directory workingDir) async {
 Future<String> lastProjectCommit() async {
   final rawCommit =
       await cmd('git log -1 --pretty=%B', workingDirectory: projectDir);
-  final formatCommit = rawCommit.replaceAll(' ', '_');
+  final formatCommit = rawCommit.replaceAll(' ', '_').replaceAll('&', '');
   return 'auto_commit:_$formatCommit';
 }
 

bin/main.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import '../patterns/observer/subscriber_flutter_widget/main.dart';
 import '../patterns/adapter/flutter_adapter/main.dart';
+import '../patterns/memento/memento_editor/main.dart';
 
 void main() {
   runApp(MyApp());
@@ -12,10 +13,11 @@ class MyApp extends StatelessWidget {
     return MaterialApp(
       title: 'Refactoring Guru: Flutter launcher',
       theme: ThemeData(primarySwatch: Colors.pink),
-      initialRoute: '/adapter/flutter_adapter',
+      initialRoute: '/memento/flutter_memento_editor',
       routes: {
         '/observer/subscriber_flutter_widget': (_) => SubscriberFlutterApp(),
         '/adapter/flutter_adapter': (_) => FlutterAdapterApp(),
+        '/memento/flutter_memento_editor': (_) => FlutterMementoEditorApp(),
       },
     );
   }

patterns/adapter/flutter_adapter/adapter/classic_app_render_object.dart

@@ -63,13 +63,16 @@ class ClassicAppRenderObject extends RenderBox {
   @override
   void handleEvent(PointerEvent event, covariant BoxHitTestEntry entry) {
     if (event is PointerHoverEvent || event is PointerMoveEvent) {
-    } else if (event is PointerDownEvent) {
-      if (event.buttons == kPrimaryMouseButton) {
-        _classicApp.onMouseDown();
-      } else if (event.buttons == kSecondaryMouseButton) {}
-      else if (event.buttons == kMiddleMouseButton) {}
+      _classicApp.onMouseMove(event.position.dx, event.position.dy);
     } else if (event is PointerScrollEvent) {
       _classicApp.onPointerWheel(event.scrollDelta.dx, event.scrollDelta.dy);
+    } else if (event is PointerDownEvent) {
+      if (event.buttons == kPrimaryMouseButton) {
+        _classicApp.onMouseDown(event.position.dx, event.position.dy);
+      } else if (event.buttons == kSecondaryMouseButton) {
+      } else if (event.buttons == kMiddleMouseButton) {}
+    } else if (event is PointerUpEvent) {
+      _classicApp.onMouseUp();
     }
   }
 

patterns/adapter/flutter_adapter/classic_app/classic_app.dart

@@ -7,7 +7,11 @@ import 'repaint_compatible.dart';
 abstract class ClassicApp implements RepaintCompatible {
   final events = AppObserver();
 
-  void onMouseDown() {}
+  void onMouseDown(double x, double y) {}
+
+  void onMouseUp() {}
+
+  void onMouseMove(double x, double y) {}
 
   void onPointerWheel(double deltaX, double deltaY) {}
 

patterns/adapter/flutter_adapter/client_app/app.dart

@@ -19,7 +19,7 @@ class App extends ClassicApp {
   }
 
   @override
-  void onMouseDown() {
+  void onMouseDown(_, __) {
     textColoring.color = colorRules.nextColor(textColoring.color);
   }
 

patterns/memento/memento_editor/README.md

@@ -0,0 +1,48 @@
+# Memento pattern
+Memento is a behavioral design pattern that lets you save and restore the previous state of an 
+object without revealing the details of its implementation.
+
+Tutorial: [here](https://refactoring.guru/design-patterns/memento).
+
+### Online demo:
+Click on the picture to see a [demo](https://RefactoringGuru.github.io/design-patterns-dart/#/memento/flutter_memento_editor).
+
+[![image](https://user-images.githubusercontent.com/8049534/165401175-88bc4593-4624-45b4-8c03-6f1390ed771a.png)](https://refactoringguru.github.io/design-patterns-dart/#/memento/flutter_memento_editor)
+
+
+### Dependency Patterns
+This complex example includes these implementations:
+- [[AppObserver](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/observer/app_observer)]
+- [[SubscriberWidget](https://github.com/RefactoringGuru/design-patterns-dart/tree/master/patterns/observer/subscriber_flutter_widget)]
+
+### Diagram:
+![image](https://user-images.githubusercontent.com/8049534/165399085-06835617-8ef1-4e2f-930f-03d730433afb.png)
+
+### Client code:
+```dart
+class MementoEditorApplication {
+  final editor = Editor();
+  final caretaker = Caretaker();
+
+  void createDefaultShapes() {/*...*/}
+
+  void saveState() {
+    final snapshot = editor.backup();
+
+    if (caretaker.isSnapshotExists(snapshot)) {
+      return;
+    }
+
+    final memento = Memento(DateTime.now(), snapshot);
+    caretaker.addMemento(memento);
+    editor.events.notify(MementoCreateEvent());
+  }
+
+  void restoreState(Memento memento) {
+    editor
+      ..unSelect()
+      ..restore(memento.snapshot)
+      ..repaint();
+  }
+}
+```

patterns/memento/memento_editor/application.dart

@@ -0,0 +1,44 @@
+import 'dart:math';
+
+import 'editor/memento_create_event.dart';
+import 'editor/editor.dart';
+import 'memento_pattern/caretaker.dart';
+import 'memento_pattern/memento.dart';
+import 'shapes/shape.dart';
+
+class MementoEditorApplication {
+  final editor = Editor();
+  final caretaker = Caretaker();
+
+  MementoEditorApplication() {
+    createDefaultShapes();
+  }
+
+  void createDefaultShapes() {
+    const radius = 300.0;
+    for (var i = 0; i < 7; i++) {
+      final x = 60 + radius + cos(i / 1.15) * radius;
+      final y = 60 + radius + sin(i / 1.15) * radius;
+      editor.shapes.add(Shape(x, y));
+    }
+  }
+
+  void saveState() {
+    final snapshot = editor.backup();
+
+    if (caretaker.isSnapshotExists(snapshot)) {
+      return;
+    }
+
+    final memento = Memento(DateTime.now(), snapshot);
+    caretaker.addMemento(memento);
+    editor.events.notify(MementoCreateEvent());
+  }
+
+  void restoreState(Memento memento) {
+    editor
+      ..unSelect()
+      ..restore(memento.snapshot)
+      ..repaint();
+  }
+}

patterns/memento/memento_editor/editor/editor.dart

@@ -0,0 +1,22 @@
+import 'dart:ui';
+
+import '../../../adapter/flutter_adapter/classic_app/classic_app.dart';
+import '../memento_pattern/originator.dart';
+import '../shapes/shapes.dart';
+import 'manipulator.dart';
+
+class Editor extends ClassicApp with Manipulator, Shapes, Originator {
+  @override
+  void onPaint(Canvas canvas, Size canvasSize) {
+    _paintBackground(canvas, canvasSize);
+    paintShapes(canvas);
+    activeShape?.paintSelectionBox(canvas);
+  }
+
+  void _paintBackground(Canvas canvas, Size canvasSize) {
+    canvas.drawRect(
+      Offset.zero & canvasSize,
+      Paint()..color = Color(0xff404040),
+    );
+  }
+}

patterns/memento/memento_editor/editor/manipulator.dart

@@ -0,0 +1,42 @@
+import '../../../adapter/flutter_adapter/classic_app/classic_app.dart';
+import '../shapes/shapes.dart';
+
+mixin Manipulator implements ClassicApp, Shapes {
+  var _isMouseDown = false;
+
+  @override
+  void onMouseDown(double x, double y) {
+    _isMouseDown = true;
+    final currSelection = activeShape;
+
+    select(x, y);
+
+    if (currSelection == activeShape) {
+      return;
+    }
+
+    if (activeShape == null) {
+      unSelect();
+    }
+
+    repaint();
+  }
+
+  @override
+  void onMouseMove(double x, double y) {
+    if (_isMouseDown) {
+      activeShape?.dragTo(x, y);
+      repaint();
+    }
+  }
+
+  @override
+  void onPointerWheel(double deltaX, double deltaY) {
+    activeShape?.changeSize(deltaY / 5);
+  }
+
+  @override
+  void onMouseUp() {
+    _isMouseDown = false;
+  }
+}

patterns/memento/memento_editor/editor/memento_create_event.dart

@@ -0,0 +1,3 @@
+import '../../../observer/app_observer/observer/event.dart';
+
+class MementoCreateEvent extends Event {}

patterns/memento/memento_editor/main.dart

@@ -0,0 +1,33 @@
+import 'package:flutter/material.dart';
+
+import '../../adapter/flutter_adapter/adapter/classic_app_adapter_widget.dart'
+    as adapter;
+import 'application.dart';
+import 'widgets/right_panel_widget.dart';
+
+
+class FlutterMementoEditorApp extends StatefulWidget {
+  @override
+  State<FlutterMementoEditorApp> createState() =>
+      _FlutterMementoEditorAppState();
+}
+
+class _FlutterMementoEditorAppState extends State<FlutterMementoEditorApp> {
+  final app = MementoEditorApplication();
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: Row(
+        children: [
+          Expanded(
+            child: adapter.ClassicAppAdapterWidget(
+              classicApp: app.editor,
+            ),
+          ),
+          RightPanelWidget(app: app),
+        ],
+      ),
+    );
+  }
+}

patterns/memento/memento_editor/memento_pattern/caretaker.dart

@@ -0,0 +1,18 @@
+import 'memento.dart';
+import 'snapshot.dart';
+
+class Caretaker {
+  final _mementoList = <Memento>[];
+
+  List<Memento> get list => List<Memento>.unmodifiable(_mementoList);
+
+  void addMemento(Memento memento) {
+    _mementoList.add(memento);
+  }
+
+  bool isSnapshotExists(Snapshot snapshot) {
+    return list.any(
+      (e) => e.snapshot == snapshot,
+    );
+  }
+}

patterns/memento/memento_editor/memento_pattern/memento.dart

@@ -0,0 +1,9 @@
+
+import 'snapshot.dart';
+
+class Memento {
+  final DateTime time;
+  final Snapshot snapshot;
+
+  Memento(this.time, this.snapshot);
+}