Adding ScaleEffect

doc/examples/effects/lib/main.dart

@@ -1,48 +1,113 @@
 import 'package:flutter/material.dart';
-import 'package:flame/game.dart';
-import 'package:flame/gestures.dart';
-import 'package:flame/components/component.dart';
-import 'package:flame/effects/effects.dart';
-import 'package:flame/position.dart';
-
-class Square extends PositionComponent {
-  static final _paint = Paint()..color = Color(0xFFFFFFFF);
-
-  Square() {
-    width = 100;
-    height = 100;
-  }
-
-  @override
-  void render(Canvas canvas) {
-    canvas.drawRect(toRect(), _paint);
-  }
-}
-
-class MyGame extends BaseGame  with TapDetector {
-  Square square;
-  MyGame() {
-    add(
-        square = Square()
-        ..x = 100
-        ..y = 100
-    );
-  }
-
-  @override
-  void onTapUp(details) {
-    square.addEffect(MoveEffect(
-            destination: Position(
-                details.localPosition.dx,
-                details.localPosition.dy,
-            ),
-            speed: 250.0,
-            curve: Curves.easeOutQuad,
-    ));
-  }
-}
 
 void main() {
-  runApp(MyGame().widget);
+  runApp(MyApp());
 }
 
+class MyApp extends StatelessWidget {
+  // This widget is the root of your application.
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        // This is the theme of your application.
+        //
+        // Try running your application with "flutter run". You'll see the
+        // application has a blue toolbar. Then, without quitting the app, try
+        // changing the primarySwatch below to Colors.green and then invoke
+        // "hot reload" (press "r" in the console where you ran "flutter run",
+        // or simply save your changes to "hot reload" in a Flutter IDE).
+        // Notice that the counter didn't reset back to zero; the application
+        // is not restarted.
+        primarySwatch: Colors.blue,
+      ),
+      home: MyHomePage(title: 'Flutter Demo Home Page'),
+    );
+  }
+}
+
+class MyHomePage extends StatefulWidget {
+  MyHomePage({Key key, this.title}) : super(key: key);
+
+  // This widget is the home page of your application. It is stateful, meaning
+  // that it has a State object (defined below) that contains fields that affect
+  // how it looks.
+
+  // This class is the configuration for the state. It holds the values (in this
+  // case the title) provided by the parent (in this case the App widget) and
+  // used by the build method of the State. Fields in a Widget subclass are
+  // always marked "final".
+
+  final String title;
+
+  @override
+  _MyHomePageState createState() => _MyHomePageState();
+}
+
+class _MyHomePageState extends State<MyHomePage> {
+  int _counter = 0;
+
+  void _incrementCounter() {
+    setState(() {
+      // This call to setState tells the Flutter framework that something has
+      // changed in this State, which causes it to rerun the build method below
+      // so that the display can reflect the updated values. If we changed
+      // _counter without calling setState(), then the build method would not be
+      // called again, and so nothing would appear to happen.
+      _counter++;
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    // This method is rerun every time setState is called, for instance as done
+    // by the _incrementCounter method above.
+    //
+    // The Flutter framework has been optimized to make rerunning build methods
+    // fast, so that you can just rebuild anything that needs updating rather
+    // than having to individually change instances of widgets.
+    return Scaffold(
+      appBar: AppBar(
+        // Here we take the value from the MyHomePage object that was created by
+        // the App.build method, and use it to set our appbar title.
+        title: Text(widget.title),
+      ),
+      body: Center(
+        // Center is a layout widget. It takes a single child and positions it
+        // in the middle of the parent.
+        child: Column(
+          // Column is also a layout widget. It takes a list of children and
+          // arranges them vertically. By default, it sizes itself to fit its
+          // children horizontally, and tries to be as tall as its parent.
+          //
+          // Invoke "debug painting" (press "p" in the console, choose the
+          // "Toggle Debug Paint" action from the Flutter Inspector in Android
+          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
+          // to see the wireframe for each widget.
+          //
+          // Column has various properties to control how it sizes itself and
+          // how it positions its children. Here we use mainAxisAlignment to
+          // center the children vertically; the main axis here is the vertical
+          // axis because Columns are vertical (the cross axis would be
+          // horizontal).
+          mainAxisAlignment: MainAxisAlignment.center,
+          children: <Widget>[
+            Text(
+              'You have pushed the button this many times:',
+            ),
+            Text(
+              '$_counter',
+              style: Theme.of(context).textTheme.headline4,
+            ),
+          ],
+        ),
+      ),
+      floatingActionButton: FloatingActionButton(
+        onPressed: _incrementCounter,
+        tooltip: 'Increment',
+        child: Icon(Icons.add),
+      ), // This trailing comma makes auto-formatting nicer for build methods.
+    );
+  }
+}

doc/examples/effects/lib/main_move.dart

@@ -0,0 +1,32 @@
+import 'package:flutter/material.dart';
+import 'package:flame/game.dart';
+import 'package:flame/gestures.dart';
+import 'package:flame/effects/effects.dart';
+import 'package:flame/position.dart';
+
+import './square.dart';
+
+class MyGame extends BaseGame with TapDetector {
+  Square square;
+  MyGame() {
+    add(square = Square()
+      ..x = 100
+      ..y = 100);
+  }
+
+  @override
+  void onTapUp(details) {
+    square.addEffect(MoveEffect(
+      destination: Position(
+        details.localPosition.dx,
+        details.localPosition.dy,
+      ),
+      speed: 250.0,
+      curve: Curves.bounceInOut,
+    ));
+  }
+}
+
+void main() {
+  runApp(MyGame().widget);
+}

doc/examples/effects/lib/main_scale.dart

@@ -0,0 +1,35 @@
+import 'package:flutter/material.dart';
+import 'package:flame/game.dart';
+import 'package:flame/gestures.dart';
+import 'package:flame/anchor.dart';
+import 'package:flame/effects/effects.dart';
+
+import './square.dart';
+
+class MyGame extends BaseGame with TapDetector {
+  Square square;
+  bool grow = true;
+
+  MyGame() {
+    add(square = Square()
+      ..anchor = Anchor.center
+      ..x = 200
+      ..y = 400);
+  }
+
+  @override
+  void onTap() {
+    final s = grow ? 300.0 : 100.0;
+
+    grow = !grow;
+    square.addEffect(ScaleEffect(
+      size: Size(s, s),
+      speed: 250.0,
+      curve: Curves.bounceInOut,
+    ));
+  }
+}
+
+void main() {
+  runApp(MyGame().widget);
+}

doc/examples/effects/lib/square.dart

@@ -0,0 +1,17 @@
+import 'package:flame/components/component.dart';
+
+import 'dart:ui';
+
+class Square extends PositionComponent {
+  static final _paint = Paint()..color = const Color(0xFFFFFFFF);
+
+  Square() {
+    width = 100;
+    height = 100;
+  }
+
+  @override
+  void render(Canvas canvas) {
+    canvas.drawRect(toRect(), _paint);
+  }
+}

lib/components/component.dart

@@ -154,10 +154,7 @@ abstract class PositionComponent extends Component {
   }
 
   void addEffect(PositionComponentEffect effect) {
-    _effects.add(
-        effect
-        ..component = this
-    );
+    _effects.add(effect..component = this);
   }
 
   @mustCallSuper

lib/effects/effects.dart

@@ -2,6 +2,7 @@ import 'package:flutter/animation.dart';
 import 'package:meta/meta.dart';
 
 import 'dart:math';
+import 'dart:ui';
 
 import '../position.dart';
 import '../components/component.dart';
@@ -10,11 +11,66 @@ abstract class PositionComponentEffect {
   void update(double dt);
   bool hasFinished();
   PositionComponent component;
+}
 
+double _direction(double p, double d) => p < d ? -1 : 1;
+double _size(double a, double b) => (a - b).abs();
+
+class ScaleEffect extends PositionComponentEffect {
+  Size size;
+  double speed;
+  Curve curve;
+
+  double _scaleTime;
+  double _ellapsedTime = 0.0;
+
+  Size _original;
+  Size _diff;
+  final Position _dir = Position(0, 0);
+
+  ScaleEffect({
+    @required this.size,
+    @required this.speed,
+    this.curve,
+  });
+
+  @override
+  set component(_comp) {
+    super.component = _comp;
+
+    _original = Size(component.width, component.height);
+    _diff = Size(
+      _size(_original.width, size.width),
+      _size(_original.height, size.height),
+    );
+
+    _dir.x = _direction(size.width, _original.width);
+    _dir.y = _direction(size.height, _original.height);
+
+    _scaleTime = max(
+      _diff.width / speed,
+      _diff.height / speed,
+    );
+  }
+
+  @override
+  void update(double dt) {
+    if (!hasFinished()) {
+      final double percent = min(1.0, _ellapsedTime / _scaleTime);
+      final double c = curve != null ? curve.transform(percent) : 1.0;
+
+      component.width = _original.width + _diff.width * c * _dir.x;
+      component.height = _original.height + _diff.height * c * _dir.y;
+    }
+
+    _ellapsedTime += dt;
+  }
+
+  @override
+  bool hasFinished() => _ellapsedTime >= _scaleTime;
 }
 
 class MoveEffect extends PositionComponentEffect {
-
   Position destination;
   double speed;
   Curve curve;
@@ -31,33 +87,33 @@ class MoveEffect extends PositionComponentEffect {
 
   double _ellapsedTime = 0.0;
 
-
-  bool _valuesInitted = false;
-
   MoveEffect({
     @required this.destination,
     @required this.speed,
     this.curve,
   });
 
+  @override
+  set component(_comp) {
+    super.component = _comp;
+
+    _xOriginal = component.x;
+    _yOriginal = component.y;
+
+    _xDistance = _size(destination.x, component.x);
+    _yDistance = _size(destination.y, component.y);
+
+    _xDirection = _direction(destination.x, component.x);
+    _yDirection = _direction(destination.y, component.y);
+
+    _travelTime = max(
+      _xDistance / speed,
+      _yDistance / speed,
+    );
+  }
+
   @override
   void update(double dt) {
-    if (!_valuesInitted) {
-      _xOriginal = component.x;
-      _xDistance = (destination.x - component.x).abs();
-      final _xTravelTime = _xDistance / speed;
-      _xDirection = destination.x < component.x ? - 1 : 1;
-
-      _yOriginal = component.y;
-      _yDistance = (destination.y - component.y).abs();
-      final _yTravelTime = _yDistance / speed;
-      _yDirection = destination.y < component.y ? - 1 : 1;
-
-      _travelTime = max(_xTravelTime, _yTravelTime);
-
-      _valuesInitted = true;
-    }
-
     if (!hasFinished()) {
       final double percent = min(1.0, _ellapsedTime / _travelTime);
       final double c = curve != null ? curve.transform(percent) : 1.0;
@@ -68,6 +124,7 @@ class MoveEffect extends PositionComponentEffect {
 
     _ellapsedTime += dt;
   }
+
   @override
-  bool hasFinished()  => _ellapsedTime >= _travelTime;
+  bool hasFinished() => _ellapsedTime >= _travelTime;
 }