Initial Commit for PlaformChannel Sample App (#453)

platform_channels/lib/main.dart

@@ -0,0 +1,70 @@
+// 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 'package:flutter/material.dart';
+import 'package:platform_channels/src/method_channel_demo.dart';
+
+void main() {
+  runApp(PlatformChannelSample());
+}
+
+class PlatformChannelSample extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      routes: {
+        '/methodChannelDemo': (context) => MethodChannelDemo(),
+      },
+      title: 'Platform Channel Sample',
+      home: HomePage(),
+    );
+  }
+}
+
+class DemoInfo {
+  final String demoTitle;
+  final String demoRoute;
+
+  DemoInfo(this.demoTitle, this.demoRoute)
+      : assert(demoTitle != null),
+        assert(demoRoute != null);
+}
+
+List<DemoInfo> demoList = [
+  DemoInfo(
+    'MethodChannelDemo',
+    '/methodChannelDemo',
+  ),
+];
+
+class HomePage extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('Platform Channel Sample'),
+      ),
+      body: ListView(
+        children: demoList.map((demoInfo) => DemoTile(demoInfo)).toList(),
+      ),
+    );
+  }
+}
+
+/// This widget is responsible for displaying the [ListTile] on [HomePage].
+class DemoTile extends StatelessWidget {
+  final DemoInfo demoInfo;
+
+  DemoTile(this.demoInfo);
+
+  @override
+  Widget build(BuildContext context) {
+    return ListTile(
+      title: Text(demoInfo.demoTitle),
+      onTap: () {
+        Navigator.pushNamed(context, demoInfo.demoRoute);
+      },
+    );
+  }
+}

platform_channels/lib/src/counter_method_channel.dart

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+// 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 'package:flutter/services.dart';
+
+/// This class includes implementation of two platform methods [increment],
+/// and [decrement] which are used to increment and decrement value
+/// of count respectively.
+class Counter {
+  /// Creates a [MethodChannel] with the specified name to invoke platform method.
+  /// In order to communicate across platforms, the name of MethodChannel
+  /// should be same on native and dart side.
+  static MethodChannel methodChannel = const MethodChannel('methodChannelDemo');
+
+  /// This method is responsible to increment and return the value of count.
+  static Future<int> increment({int counterValue}) async {
+    final result = await methodChannel
+        .invokeMethod<int>('increment', {'count': counterValue});
+    return result;
+  }
+
+  /// This method is responsible to decrement and return the value of count.
+  static Future<int> decrement({int counterValue}) async {
+    final result = await methodChannel
+        .invokeMethod<int>('decrement', {'count': counterValue});
+    return result;
+  }
+}

platform_channels/lib/src/method_channel_demo.dart

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+// 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 'package:flutter/material.dart';
+import 'package:platform_channels/src/counter_method_channel.dart';
+
+/// The widget demonstrates how to use [MethodChannel] to invoke platform methods.
+/// It has two [RaisedButton]s to increment and decrement the value of
+/// [count], and a [Text] widget to display its value.
+class MethodChannelDemo extends StatefulWidget {
+  @override
+  _MethodChannelDemoState createState() => _MethodChannelDemoState();
+}
+
+class _MethodChannelDemoState extends State<MethodChannelDemo> {
+  int count = 0;
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text('MethodChannel Demo'),
+      ),
+      body: Builder(
+        builder: (context) {
+          return Column(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: [
+              Text(
+                'Value of count is $count',
+                style: Theme.of(context).textTheme.headline5,
+              ),
+              SizedBox(
+                height: 16,
+              ),
+              Row(
+                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
+                children: [
+                  // Whenever users press the RaisedButton, it invokes
+                  // Counter.increment method to increment the value of count.
+                  RaisedButton.icon(
+                    onPressed: () async {
+                      try {
+                        final value =
+                            await Counter.increment(counterValue: count);
+                        setState(() => count = value);
+                      } catch (error) {
+                        showErrorMessage(
+                          context,
+                          error.message as String,
+                        );
+                      }
+                    },
+                    icon: Icon(Icons.add),
+                    label: Text('Increment'),
+                  ),
+
+                  // Whenever users press the RaisedButton, it invokes
+                  // Counter.decrement method to decrement the value of count.
+                  RaisedButton.icon(
+                    onPressed: () async {
+                      try {
+                        final value =
+                            await Counter.decrement(counterValue: count);
+                        setState(() => count = value);
+                      } catch (error) {
+                        showErrorMessage(
+                          context,
+                          error.message as String,
+                        );
+                      }
+                    },
+                    icon: Icon(Icons.remove),
+                    label: Text('Decrement'),
+                  )
+                ],
+              )
+            ],
+          );
+        },
+      ),
+    );
+  }
+
+  void showErrorMessage(BuildContext context, String errorMessage) {
+    Scaffold.of(context).showSnackBar(SnackBar(
+      content: Text(errorMessage),
+    ));
+  }
+}