创建一个构建方法,它随机选择 class 中的一个 object 并在其中传输 object 的参数
Create a build method which randomly selects one object of a class and transfers in it parameters of object
我是 flutter (dart) 的新手。我创建了一个包含三个字段(frontColor、angle 和 rearColor)的 class,同样基于此 class 我创建了六个带有参数的 objects(这里我只插入其中两个)。我需要一个小部件,它将随机 select objects 之一并使用 SizedBox 在 child 中显示它(这里必须是我们的小部件),例如:
Center(
child: SizedBox(
height: 142,
width: 141,
child: ...
),
),
这是我创建的 class 和 objects:
class Circle {
Color frontColor;
ColorFilter rearColor;
double angle;
Circle(
this.frontColor,
this.rearColor,
this.angle,
);
}
Circle firstCircle = Circle(
const Color(0xFF41AB9D),
const ColorFilter.mode(Color(0xFF49C1B0), BlendMode.srcATop),
0.0,
);
Circle fourthCircle = Circle(
const Color(0xFF49C1B0),
const ColorFilter.mode(Color(0xFF41AB9D), BlendMode.srcATop),
360 / 30,
);
结果我应该得到类似的东西,但参数必须从外部传输:
Widget _circleBackground() {
return Container(
width: 141,
height: 142,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(2500.0),
color: const Color(0xFF41AB9D),
image: const DecorationImage(
colorFilter: ColorFilter.mode(Color(0xFF49C1B0), BlendMode.srcATop),
image: AssetImage('...'),
),
),
);}
可以使用stream,在statefulWidget中添加一个Widget类型的变量作为state变量,然后在listen中修改该变量,如下所示:
在 main.dart 上:
import 'dart:async';
import 'dart:math';
import 'package:flutter/material.dart';
import 'package:futurebuildertest/circle.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatefulWidget {
const MyApp({Key? key}) : super(key: key);
@override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
Widget child = Container();
final List<Circle> widgets = [firstCircle, secondCircle, fourthCircle];
final StreamController streamController = StreamController();
@override
void initState() {
super.initState();
child = _circleBackground(firstCircle);
streamController.stream.listen((_) {
Circle param = widgets[Random().nextInt(3)];
setState(() {
child = _circleBackground(param);
});
});
}
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Column(children: [
Expanded(
child: Center(child: child)
),
ElevatedButton(
onPressed: () {
streamController.add("");
},
child: Container(
padding: const EdgeInsets.all(16),
child: const Text("Change"),
)
)
]),
);
}
Widget _circleBackground(Circle circle) {
return Container(
width: 141,
height: 142,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(2500.0),
color: circle.frontColor,
),
child: const SizedBox(
height: 100,
width: 100,
),
);
}
}
在 circle.dart
import 'package:flutter/material.dart';
class Circle {
final Color frontColor;
final ColorFilter rearColor;
double angle;
Circle(
this.frontColor,
this.rearColor,
this.angle,
);
}
Circle firstCircle = Circle(
const Color(0xFFF56302),
const ColorFilter.mode(Color(0xFF49C1B0), BlendMode.srcATop),
0.0,
);
Circle secondCircle = Circle(
const Color(0xFF1EFF00),
const ColorFilter.mode(Color(0xFF41AB9D), BlendMode.srcATop),
360 / 30,
);
Circle fourthCircle = Circle(
const Color(0xFF49C1B0),
const ColorFilter.mode(Color(0xFF41AB9D), BlendMode.srcATop),
360 / 30,
);
这只是一个演示如何完成的 poc。
我是 flutter (dart) 的新手。我创建了一个包含三个字段(frontColor、angle 和 rearColor)的 class,同样基于此 class 我创建了六个带有参数的 objects(这里我只插入其中两个)。我需要一个小部件,它将随机 select objects 之一并使用 SizedBox 在 child 中显示它(这里必须是我们的小部件),例如:
Center(
child: SizedBox(
height: 142,
width: 141,
child: ...
),
),
这是我创建的 class 和 objects:
class Circle {
Color frontColor;
ColorFilter rearColor;
double angle;
Circle(
this.frontColor,
this.rearColor,
this.angle,
);
}
Circle firstCircle = Circle(
const Color(0xFF41AB9D),
const ColorFilter.mode(Color(0xFF49C1B0), BlendMode.srcATop),
0.0,
);
Circle fourthCircle = Circle(
const Color(0xFF49C1B0),
const ColorFilter.mode(Color(0xFF41AB9D), BlendMode.srcATop),
360 / 30,
);
结果我应该得到类似的东西,但参数必须从外部传输:
Widget _circleBackground() {
return Container(
width: 141,
height: 142,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(2500.0),
color: const Color(0xFF41AB9D),
image: const DecorationImage(
colorFilter: ColorFilter.mode(Color(0xFF49C1B0), BlendMode.srcATop),
image: AssetImage('...'),
),
),
);}
可以使用stream,在statefulWidget中添加一个Widget类型的变量作为state变量,然后在listen中修改该变量,如下所示:
在 main.dart 上:
import 'dart:async';
import 'dart:math';
import 'package:flutter/material.dart';
import 'package:futurebuildertest/circle.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatefulWidget {
const MyApp({Key? key}) : super(key: key);
@override
State<MyApp> createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
Widget child = Container();
final List<Circle> widgets = [firstCircle, secondCircle, fourthCircle];
final StreamController streamController = StreamController();
@override
void initState() {
super.initState();
child = _circleBackground(firstCircle);
streamController.stream.listen((_) {
Circle param = widgets[Random().nextInt(3)];
setState(() {
child = _circleBackground(param);
});
});
}
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Column(children: [
Expanded(
child: Center(child: child)
),
ElevatedButton(
onPressed: () {
streamController.add("");
},
child: Container(
padding: const EdgeInsets.all(16),
child: const Text("Change"),
)
)
]),
);
}
Widget _circleBackground(Circle circle) {
return Container(
width: 141,
height: 142,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(2500.0),
color: circle.frontColor,
),
child: const SizedBox(
height: 100,
width: 100,
),
);
}
}
在 circle.dart
import 'package:flutter/material.dart';
class Circle {
final Color frontColor;
final ColorFilter rearColor;
double angle;
Circle(
this.frontColor,
this.rearColor,
this.angle,
);
}
Circle firstCircle = Circle(
const Color(0xFFF56302),
const ColorFilter.mode(Color(0xFF49C1B0), BlendMode.srcATop),
0.0,
);
Circle secondCircle = Circle(
const Color(0xFF1EFF00),
const ColorFilter.mode(Color(0xFF41AB9D), BlendMode.srcATop),
360 / 30,
);
Circle fourthCircle = Circle(
const Color(0xFF49C1B0),
const ColorFilter.mode(Color(0xFF41AB9D), BlendMode.srcATop),
360 / 30,
);
这只是一个演示如何完成的 poc。