Quarterly maintenance on isolate_example (#142)

Author: RedBrogdon

Diff for: MAINTENANCE.md

@@ -10,7 +10,7 @@ match any new language/SDK features, etc.).
 | chrome-os-best-practices  |                    |                |
 | experimental              |                    |                |
 | flutter_maps_firestore    |                    |                |
-| isolate_example           |                    |                |
+| isolate_example           | redbrogdon         | 9/12/19        |
 | jsonexample               |                    |                |
 | material_studies/shrine   |                    |                |
 | place_tracker             |                    |                |

Diff for: isolate_example/.gitignore

@@ -15,8 +15,10 @@
 *.iws
 .idea/
 
-# Visual Studio Code related
-.vscode/
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
 
 # Flutter/Dart/Pub related
 **/doc/api/
@@ -59,6 +61,7 @@
 **/ios/Flutter/app.flx
 **/ios/Flutter/app.zip
 **/ios/Flutter/flutter_assets/
+**/ios/Flutter/flutter_export_environment.sh
 **/ios/ServiceDefinitions.json
 **/ios/Runner/GeneratedPluginRegistrant.*
 
@@ -67,5 +70,4 @@
 !**/ios/**/default.mode2v3
 !**/ios/**/default.pbxuser
 !**/ios/**/default.perspectivev3
-!/packages/flutter_tools/test/data/dart_dependencies_test/**/.packages
-bash: parse_git_branch: command not found
+!/packages/flutter_tools/test/data/dart_dependencies_test/**/.packages

Diff for: isolate_example/.metadata

@@ -0,0 +1,10 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled and should not be manually edited.
+
+version:
+  revision: 2d2a1ffec95cc70a3218872a2cd3f8de4933c42f
+  channel: stable
+
+project_type: app

Diff for: isolate_example/android/app/src/main/kotlin/dev/flutter/isolate_example/MainActivity.kt

@@ -0,0 +1,13 @@
+package dev.flutter.isolate_example
+
+import android.os.Bundle
+
+import io.flutter.app.FlutterActivity
+import io.flutter.plugins.GeneratedPluginRegistrant
+
+class MainActivity: FlutterActivity() {
+  override fun onCreate(savedInstanceState: Bundle?) {
+    super.onCreate(savedInstanceState)
+    GeneratedPluginRegistrant.registerWith(this)
+  }
+}

Diff for: isolate_example/ios/Runner/AppDelegate.swift

@@ -0,0 +1,13 @@
+import UIKit
+import Flutter
+
+@UIApplicationMain
+@objc class AppDelegate: FlutterAppDelegate {
+  override func application(
+    _ application: UIApplication,
+    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
+  ) -> Bool {
+    GeneratedPluginRegistrant.register(with: self)
+    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
+  }
+}

Diff for: isolate_example/ios/Runner/Runner-Bridging-Header.h

@@ -0,0 +1 @@
+#import "GeneratedPluginRegistrant.h"

Diff for: isolate_example/lib/main.dart

@@ -15,10 +15,16 @@
 import 'package:flutter/material.dart';
 
 import 'page_one.dart';
-import 'page_two.dart';
 import 'page_three.dart';
+import 'page_two.dart';
 
-void main() => runApp(MaterialApp(home: StartApp()));
+void main() {
+  runApp(
+    MaterialApp(
+      home: StartApp(),
+    ),
+  );
+}
 
 class StartApp extends StatelessWidget {
   @override
@@ -30,9 +36,18 @@ class StartApp extends StatelessWidget {
           appBar: AppBar(
             bottom: TabBar(
               tabs: [
-                Tab(icon: Icon(Icons.flash_on), text: 'Performance'),
-                Tab(icon: Icon(Icons.sync), text: 'Infinite Process'),
-                Tab(icon: Icon(Icons.storage), text: 'Data Transfer'),
+                Tab(
+                  icon: Icon(Icons.flash_on),
+                  text: 'Performance',
+                ),
+                Tab(
+                  icon: Icon(Icons.sync),
+                  text: 'Infinite Process',
+                ),
+                Tab(
+                  icon: Icon(Icons.storage),
+                  text: 'Data Transfer',
+                ),
               ],
             ),
             title: Text('Isolate Example'),

Diff for: isolate_example/lib/page_one.dart

@@ -15,6 +15,20 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 
+// Computes the nth number in the Fibonacci sequence.
+int fib(int n) {
+  int number1 = n - 1;
+  int number2 = n - 2;
+
+  if (n == 1) {
+    return 0;
+  } else if (n == 0) {
+    return 1;
+  } else {
+    return (fib(number1) + fib(number2));
+  }
+}
+
 class PerformancePage extends StatefulWidget {
   @override
   _PerformancePageState createState() => _PerformancePageState();
@@ -65,7 +79,9 @@ class _PerformancePageState extends State<PerformancePage> {
   }
 
   VoidCallback createMainIsolateCallBack(
-      BuildContext context, AsyncSnapshot snapshot) {
+    BuildContext context,
+    AsyncSnapshot snapshot,
+  ) {
     if (snapshot.connectionState == ConnectionState.done) {
       return () {
         setState(() {
@@ -101,27 +117,20 @@ class _PerformancePageState extends State<PerformancePage> {
       return null;
     }
   }
-}
-
-Future<void> computeOnMainIsolate() async {
-  // The isolate will need a little time to disable the buttons before the performance hit.
-  await Future.delayed(Duration(milliseconds: 100), () => fib(45));
-}
-
-Future<void> computeOnSecondaryIsolate() async {
-  await compute(fib, 45);
-}
 
-int fib(int n) {
-  int number1 = n - 1;
-  int number2 = n - 2;
+  Future<void> computeOnMainIsolate() async {
+    // A delay is added here to give Flutter the chance to redraw the UI at least
+    // once before the computation (which, since it's run on the main isolate,
+    // will lock up the app) begins executing.
+    await Future.delayed(
+      Duration(milliseconds: 100),
+      () => fib(45),
+    );
+  }
 
-  if (n == 1) {
-    return 0;
-  } else if (n == 0) {
-    return 1;
-  } else {
-    return (fib(number1) + fib(number2));
+  Future<void> computeOnSecondaryIsolate() async {
+    // Compute the Fibonacci series on a secondary isolate.
+    await compute(fib, 45);
   }
 }
 
@@ -133,44 +142,32 @@ class SmoothAnimationWidget extends StatefulWidget {
 class SmoothAnimationWidgetState extends State<SmoothAnimationWidget>
     with TickerProviderStateMixin {
   AnimationController _controller;
-  Animation<BorderRadius> borderRadius;
+  Animation<BorderRadius> _borderAnimation;
 
   @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();
-              }
-            },
-          );
+    _controller = AnimationController(
+      duration: const Duration(seconds: 1),
+      vsync: this,
+    );
 
-    borderRadius = BorderRadiusTween(
+    _borderAnimation = BorderRadiusTween(
       begin: BorderRadius.circular(100.0),
       end: BorderRadius.circular(0.0),
-    ).animate(
-      CurvedAnimation(
-        parent: _controller,
-        curve: Curves.linear,
-      ),
-    );
+    ).animate(_controller);
 
-    _controller.forward();
+    _controller.repeat(reverse: true);
   }
 
   @override
   Widget build(BuildContext context) {
-    return AnimatedBuilder(
-      animation: borderRadius,
-      builder: (context, child) {
-        return Center(
-          child: Container(
+    return Center(
+      child: AnimatedBuilder(
+        animation: _borderAnimation,
+        builder: (context, child) {
+          return Container(
             child: FlutterLogo(
               size: 200,
             ),
@@ -180,13 +177,16 @@ class SmoothAnimationWidgetState extends State<SmoothAnimationWidget>
             decoration: BoxDecoration(
               gradient: LinearGradient(
                 begin: Alignment.topLeft,
-                colors: [Colors.blueAccent, Colors.redAccent],
+                colors: [
+                  Colors.blueAccent,
+                  Colors.redAccent,
+                ],
               ),
-              borderRadius: borderRadius.value,
+              borderRadius: _borderAnimation.value,
             ),
-          ),
-        );
-      },
+          );
+        },
+      ),
     );
   }