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samples/isolate_example/lib/performance_page.dart

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5.3 KiB

// 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/foundation.dart';
import 'package:flutter/material.dart';
// Computes the nth number in the Fibonacci sequence.
int fib(int n) {
var a = n - 1;
var b = n - 2;
if (n == 1) {
return 0;
} else if (n == 0) {
return 1;
} else {
return (fib(a) + fib(b));
}
}
class PerformancePage extends StatefulWidget {
@override
_PerformancePageState createState() => _PerformancePageState();
}
class _PerformancePageState extends State<PerformancePage> {
Future<void> computeFuture = Future.value();
@override
Widget build(BuildContext context) {
return Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
SmoothAnimationWidget(),
Container(
alignment: Alignment.bottomCenter,
padding: EdgeInsets.only(top: 150),
child: Column(
children: [
FutureBuilder(
future: computeFuture,
builder: (context, snapshot) {
return RaisedButton(
child: const Text('Compute on Main'),
elevation: 8.0,
onPressed:
snapshot.connectionState == ConnectionState.done
? () => handleComputeOnMain(context)
: null,
);
},
),
FutureBuilder(
future: computeFuture,
builder: (context, snapshot) {
return RaisedButton(
child: const Text('Compute on Secondary'),
elevation: 8.0,
onPressed:
snapshot.connectionState == ConnectionState.done
? () => handleComputeOnSecondary(context)
: null);
},
),
],
),
),
],
),
);
}
void handleComputeOnMain(BuildContext context) {
var future = computeOnMainIsolate()
..then((_) {
var snackBar = SnackBar(
content: Text('Main Isolate Done!'),
);
Scaffold.of(context).showSnackBar(snackBar);
});
setState(() {
computeFuture = future;
});
}
void handleComputeOnSecondary(BuildContext context) {
var future = computeOnSecondaryIsolate()
..then((_) {
var snackBar = SnackBar(
content: Text('Secondary Isolate Done!'),
);
Scaffold.of(context).showSnackBar(snackBar);
});
setState(() {
computeFuture = future;
});
}
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<void>.delayed(Duration(milliseconds: 100));
fib(45);
}
Future<void> computeOnSecondaryIsolate() async {
// Compute the Fibonacci series on a secondary isolate.
await compute(fib, 45);
}
}
class SmoothAnimationWidget extends StatefulWidget {
@override
SmoothAnimationWidgetState createState() => SmoothAnimationWidgetState();
}
class SmoothAnimationWidgetState extends State<SmoothAnimationWidget>
with TickerProviderStateMixin {
AnimationController _animationController;
Animation<BorderRadius> _borderAnimation;
@override
void initState() {
super.initState();
_animationController =
AnimationController(duration: const Duration(seconds: 1), vsync: this);
_borderAnimation = BorderRadiusTween(
begin: BorderRadius.circular(100.0),
end: BorderRadius.circular(0.0))
.animate(_animationController);
_animationController.repeat(reverse: true);
}
@override
Widget build(BuildContext context) {
return Center(
child: AnimatedBuilder(
animation: _borderAnimation,
builder: (context, child) {
return Container(
child: FlutterLogo(
size: 200,
),
alignment: Alignment.bottomCenter,
width: 350,
height: 200,
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topLeft,
colors: [
Colors.blueAccent,
Colors.redAccent,
],
),
borderRadius: _borderAnimation.value,
),
);
},
),
);
}
@override
void dispose() {
_animationController.dispose();
super.dispose();
}
}