adding Widget Switch Demo dart file

Author: TechieBlossom

widgetswitchdemo.dart

@@ -0,0 +1,131 @@
+import 'package:flutter/material.dart';
+
+enum WidgetMarker { graph, stats, info }
+
+class WidgetSwitchDemo extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      home: Scaffold(
+        appBar: AppBar(
+          title: Text("WidgetSwitchDemo"),
+        ),
+        body: BodyWidget(),
+      ),
+    );
+  }
+}
+
+class BodyWidget extends StatefulWidget {
+  @override
+  State<StatefulWidget> createState() => BodyWidgetState();
+}
+
+class BodyWidgetState extends State<BodyWidget> with SingleTickerProviderStateMixin<BodyWidget> {
+  WidgetMarker selectedWidgetMarker = WidgetMarker.graph;
+  AnimationController _controller;
+  Animation _animation;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = AnimationController(vsync: this, duration: Duration(milliseconds: 500));
+    _animation = Tween(begin: 0.0, end: 1.0).animate(_controller);
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
+    _controller.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Column(
+      children: <Widget>[
+        Row(
+          mainAxisAlignment: MainAxisAlignment.spaceBetween,
+          children: <Widget>[
+            FlatButton(
+              onPressed: () {
+                setState(() {
+                  selectedWidgetMarker = WidgetMarker.graph;
+                });
+              },
+              child: Text("Graph", style: TextStyle(color: (selectedWidgetMarker == WidgetMarker.graph) ? Colors.black : Colors.black12),),
+            ),
+            FlatButton(
+              onPressed: () {
+                setState(() {
+                  selectedWidgetMarker = WidgetMarker.stats;
+                });
+              },
+              child: Text("Stats", style: TextStyle(color: (selectedWidgetMarker == WidgetMarker.stats) ? Colors.black : Colors.black12)),
+            ),
+            FlatButton(
+              onPressed: () {
+                setState(() {
+                  selectedWidgetMarker = WidgetMarker.info;
+                });
+              },
+              child: Text("Info", style: TextStyle(color: (selectedWidgetMarker == WidgetMarker.info) ? Colors.black : Colors.black12)),
+            ),
+          ],
+        ),
+        FutureBuilder(
+          future: _playAnimation(),
+          builder: (BuildContext context, AsyncSnapshot snapshot) {
+            return getCustomContainer();
+          },
+        )
+      ],
+    );
+  }
+
+  _playAnimation() {
+    _controller.reset();
+    _controller.forward();
+  }
+
+  Widget getCustomContainer() {
+    switch (selectedWidgetMarker) {
+      case WidgetMarker.graph:
+        return getGraphContainer();
+      case WidgetMarker.stats:
+        return getStatsContainer();
+      case WidgetMarker.info:
+        return getInfoContainer();
+    }
+    return getGraphContainer();
+  }
+
+  Widget getGraphContainer() {
+    return FadeTransition(
+      opacity: _animation,
+      child: Container(
+        color: Colors.red,
+        height: 200,
+      ),
+    );
+  }
+
+  Widget getStatsContainer() {
+    return FadeTransition(
+      opacity: _animation,
+      child: Container(
+        color: Colors.green,
+        height: 300,
+      ),
+    );
+  }
+
+  Widget getInfoContainer() {
+    return FadeTransition(
+      opacity: _animation,
+      child: Container(
+        color: Colors.blue,
+        height: 400,
+      ),
+    );
+  }
+}