Added the main animation for page 1 (#94)

isolate_example/lib/main.dart

@@ -14,6 +14,10 @@
 
 import 'package:flutter/material.dart';
 
+import 'page_one.dart';
+import 'page_two.dart';
+import 'page_three.dart';
+
 void main() {
   runApp(StartApp());
 }
@@ -47,30 +51,3 @@ class StartApp extends StatelessWidget {
     );
   }
 }
-
-class PerformancePage extends StatelessWidget {
-  @override
-  Widget build(BuildContext context) {
-    return Center(
-      child: Text('Welcome to the Performance Page'),
-    );
-  }
-}
-
-class InfiniteProcessPage extends StatelessWidget {
-  @override
-  Widget build(BuildContext context) {
-    return Center(
-      child: Text('Welcome to the Infinite Process Page'),
-    );
-  }
-}
-
-class DataTransferPage extends StatelessWidget {
-  @override
-  Widget build(BuildContext context) {
-    return Center(
-      child: Text('Welcome to the Data Transfer Page'),
-    );
-  }
-}

isolate_example/lib/page_one.dart

@@ -0,0 +1,102 @@
+// Copyright 2019-present the Flutter authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import 'package:flutter/material.dart';
+
+class PerformancePage extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Column(
+        mainAxisSize: MainAxisSize.min,
+        children: <Widget>[
+          SmoothAnimationWidget(),
+        ],
+      ),
+    );
+  }
+}
+
+class SmoothAnimationWidget extends StatefulWidget {
+  @override
+  SmoothAnimationWidgetState createState() => SmoothAnimationWidgetState();
+}
+
+class SmoothAnimationWidgetState extends State<SmoothAnimationWidget>
+    with TickerProviderStateMixin {
+  AnimationController _controller;
+  var borderRadius;
+
+  @override
+  void initState() {
+    super.initState();
+
+    _controller = AnimationController(
+      duration: const Duration(seconds: 1),
+      vsync: this,
+    )..addStatusListener(
+        (status) {
+          if (status == AnimationStatus.completed) {
+            _controller.reverse();
+          } else if (status == AnimationStatus.dismissed) {
+            _controller.forward();
+          }
+        },
+      );
+
+    borderRadius = BorderRadiusTween(
+      begin: BorderRadius.circular(100.0),
+      end: BorderRadius.circular(0.0),
+    ).animate(
+      CurvedAnimation(
+        parent: _controller,
+        curve: Curves.linear,
+      ),
+    );
+
+    _controller.forward();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AnimatedBuilder(
+      animation: borderRadius,
+      builder: (context, child) {
+        return Center(
+          child: Container(
+            child: new FlutterLogo(
+              size: 200,
+            ),
+            alignment: Alignment.bottomCenter,
+            width: 350,
+            height: 200,
+            decoration: BoxDecoration(
+              gradient: LinearGradient(
+                begin: Alignment.topLeft,
+                colors: [Colors.blueAccent, Colors.redAccent],
+              ),
+              borderRadius: borderRadius.value,
+            ),
+          ),
+        );
+      },
+    );
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+}

isolate_example/lib/page_three.dart

@@ -0,0 +1,24 @@
+// Copyright 2019-present the Flutter authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import 'package:flutter/material.dart';
+
+class DataTransferPage extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Text('Welcome to the Data Transfer Page'),
+    );
+  }
+}

isolate_example/lib/page_two.dart

@@ -0,0 +1,24 @@
+// Copyright 2019-present the Flutter authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import 'package:flutter/material.dart';
+
+class InfiniteProcessPage extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Text('Welcome to the Infinite Process Page'),
+    );
+  }
+}