Added more examples in animations (#341)

animations/lib/main.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
-
 import 'src/basics/01_animated_container.dart';
 import 'src/basics/02_page_route_builder.dart';
 import 'src/basics/03_animation_controller.dart';
@@ -12,6 +11,8 @@ import 'src/basics/05_animated_builder.dart';
 import 'src/basics/06_custom_tween.dart';
 import 'src/basics/07_tween_sequence.dart';
 import 'src/basics/08_fade_transition.dart';
+import 'src/basics/09_animated_positioned.dart';
+import 'src/basics/10_animated_switcher.dart';
 import 'src/misc/hero_animation.dart';
 import 'src/misc/animated_list.dart';
 import 'src/misc/card_swipe.dart';
@@ -64,6 +65,14 @@ final basicDemos = [
       name: 'Fade Transition',
       route: FadeTransitionDemo.routeName,
       builder: (context) => FadeTransitionDemo()),
+  Demo(
+      name: 'AnimatedPositioned',
+      route: AnimatedPositionedDemo.routeName,
+      builder: (context) => AnimatedPositionedDemo()),
+  Demo(
+      name: 'AnimatedSwitcher',
+      route: AnimatedSwitcherDemo.routeName,
+      builder: (context) => AnimatedSwitcherDemo())
 ];
 
 final miscDemos = [

animations/lib/src/basics/09_animated_positioned.dart

@@ -0,0 +1,79 @@
+// Copyright 2020 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 'dart:math';
+
+import 'package:flutter/material.dart';
+
+class AnimatedPositionedDemo extends StatefulWidget {
+  static String routeName = '/basics/09_animated_positioned';
+
+  _AnimatedPositionedDemoState createState() => _AnimatedPositionedDemoState();
+}
+
+class _AnimatedPositionedDemoState extends State<AnimatedPositionedDemo> {
+  double topPosition;
+  double leftPosition;
+
+  double generateTopPosition(double top) => Random().nextDouble() * top;
+
+  double generateLeftPosition(double left) => Random().nextDouble() * left;
+
+  void initState() {
+    super.initState();
+    topPosition = generateTopPosition(30);
+    leftPosition = generateLeftPosition(30);
+  }
+
+  void changePosition(double top, double left) {
+    setState(() {
+      topPosition = generateTopPosition(top);
+      leftPosition = generateLeftPosition(left);
+    });
+  }
+
+  Widget build(BuildContext context) {
+    final size = MediaQuery.of(context).size;
+    final appBar = AppBar();
+    final topPadding = MediaQuery.of(context).padding.top;
+    // AnimatedPositioned animates changes to a widget's position within a Stack
+    return SafeArea(
+      child: Scaffold(
+        appBar: appBar,
+        body: Container(
+          height: size.height,
+          width: size.width,
+          child: Stack(
+            children: [
+              AnimatedPositioned(
+                top: topPosition,
+                left: leftPosition,
+                duration: Duration(seconds: 1),
+                child: InkWell(
+                  onTap: () => changePosition(
+                      size.height -
+                          (appBar.preferredSize.height + topPadding + 50),
+                      size.width - 150),
+                  child: Container(
+                    alignment: Alignment.center,
+                    width: 150,
+                    height: 50,
+                    child: Text(
+                      "Click Me",
+                      style: TextStyle(
+                        color:
+                            Theme.of(context).buttonTheme.colorScheme.onPrimary,
+                      ),
+                    ),
+                    color: Theme.of(context).primaryColor,
+                  ),
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}

animations/lib/src/basics/10_animated_switcher.dart

@@ -0,0 +1,72 @@
+// Copyright 2020 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 'dart:math';
+
+import 'package:flutter/material.dart';
+
+Color generateColor() => Color(0xFFFFFFFF & Random().nextInt(0xFFFFFFFF));
+
+Widget generateContainer(int keyCount) => Container(
+      key: ValueKey<int>(keyCount),
+      height: Random().nextDouble() * 200,
+      width: Random().nextDouble() * 200,
+      decoration: BoxDecoration(
+        color: generateColor(),
+        borderRadius: BorderRadius.circular(Random().nextDouble() * 100),
+        border: Border.all(
+          color: generateColor(),
+          width: Random().nextDouble() * 5,
+        ),
+      ),
+    );
+
+class AnimatedSwitcherDemo extends StatefulWidget {
+  static String routeName = '/basics/10_animated_switcher';
+
+  _AnimatedSwitcherDemoState createState() => _AnimatedSwitcherDemoState();
+}
+
+class _AnimatedSwitcherDemoState extends State<AnimatedSwitcherDemo> {
+  Widget container;
+  int keyCount;
+
+  void initState() {
+    super.initState();
+    keyCount = 0;
+    container = generateContainer(keyCount);
+  }
+
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        actions: [
+          MaterialButton(
+            onPressed: () => setState(
+              () => container = generateContainer(++keyCount),
+            ),
+            child: Text(
+              "Change Widget",
+              style: TextStyle(
+                  color: Theme.of(context).buttonTheme.colorScheme.onPrimary),
+            ),
+          ),
+        ],
+      ),
+      body: Center(
+        // AnimatedSwitcher Widget is used to switch between different widgets
+        // with a given transition. You can change the transitions by using
+        // transitionBuilder property.
+        child: AnimatedSwitcher(
+          duration: Duration(seconds: 1),
+          child: container,
+          transitionBuilder: (child, animation) => ScaleTransition(
+            child: child,
+            scale: animation,
+          ),
+        ),
+      ),
+    );
+  }
+}

animations/lib/src/misc/animated_list.dart

@@ -6,7 +6,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 
 class AnimatedListDemo extends StatefulWidget {
-  static String routeName = '/basics/08_animated_list';
+  static String routeName = '/misc/animated_list';
 
   _AnimatedListDemoState createState() => _AnimatedListDemoState();
 }

animations/pubspec.lock

@@ -169,7 +169,7 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.11"
+    version: "0.2.15"
   typed_data:
     dependency: transitive
     description:

animations/test/widget_test.dart

@@ -5,12 +5,11 @@
 // gestures. You can also use WidgetTester to find child widgets in the widget
 // tree, read text, and verify that the values of widget properties are correct.
 
+import 'package:animations/main.dart';
 import 'package:flutter_test/flutter_test.dart';
 
-import 'package:animations/main.dart';
-
 void main() {
-  testWidgets('Counter increments smoke test', (tester) async {
+  testWidgets('smoke test', (tester) async {
     // Build our app and trigger a frame.
     await tester.pumpWidget(AnimationSamples());