更改主题颜色
Change color of Theme
我想在我的应用程序中更改计数器的颜色。我想这样做:当计数器大于 0 时,将计数器的颜色更改为蓝色。如果计数器小于 0,则将计数器的颜色更改为 red.if 计数器等于 0,将计数器的颜色更改为绿色。可能吗?我只做了 2 种颜色。
这是我的代码:
import 'package:flutter/material.dart';
void main() {
runApp(Myapp());
}
class Myapp extends StatefulWidget {
@override
_MyappState createState() => _MyappState();
}
class _MyappState extends State<Myapp> {
@override
Widget build(BuildContext context) {
// TODO: implement build
return MaterialApp(
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Myhomepage(
title: "My Home Page",
),
);
}
}
class Myhomepage extends StatefulWidget {
final String title;
Myhomepage({this.title});
@override
_MyhomepageState createState() => _MyhomepageState();
}
class _MyhomepageState extends State<Myhomepage> {
int counter = 0;
@override
Widget build(BuildContext context) {
// TODO: implement build
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
centerTitle: true,
),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.add),
backgroundColor: Colors.grey[850],
onPressed: () {
setState(() {
counter++;
});
}),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
RaisedButton(
child: Text(
"Increase",
),
color: Colors.green,
onPressed: () {
setState(() {
counter++;
});
},
),
Text("The count of press button:"),
Text(
"$counter",
style: Theme.of(context).textTheme.display2.copyWith(color: counter<=0 ? Colors.red : Colors.blue)
),
RaisedButton(
child: Text(
"Decrease",
),
color: Colors.red,
onPressed: () {
setState(() {
counter--;
});
},
),
],
),
),
);
}
}
这是我的结果:
这是您实现所需系统的一种方法。我刚刚做了一个 returns 所需颜色的函数。
class _MyhomepageState extends State<Myhomepage> {
int counter = 0;
Color _getCounterColor() {
if (counter > 0) return Colors.blue;
else if (counter < 0) return Colors.red;
else return Colors.green;
}
@override
Widget build(BuildContext context) {
// TODO: implement build
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
centerTitle: true,
),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.add),
backgroundColor: Colors.grey[850],
onPressed: () {
setState(() {
counter++;
});
}),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
RaisedButton(
child: Text(
"Increase",
),
color: Colors.green,
onPressed: () {
setState(() {
counter++;
});
},
),
Text("The count of press button:"),
Text(
"$counter",
style: Theme.of(context).textTheme.display2.copyWith(color: _getCounterColor()),
),
RaisedButton(
child: Text(
"Decrease",
),
color: Colors.red,
onPressed: () {
setState(() {
counter--;
});
},
),
],
),
),
);
}
}
我想在我的应用程序中更改计数器的颜色。我想这样做:当计数器大于 0 时,将计数器的颜色更改为蓝色。如果计数器小于 0,则将计数器的颜色更改为 red.if 计数器等于 0,将计数器的颜色更改为绿色。可能吗?我只做了 2 种颜色。
这是我的代码:
import 'package:flutter/material.dart';
void main() {
runApp(Myapp());
}
class Myapp extends StatefulWidget {
@override
_MyappState createState() => _MyappState();
}
class _MyappState extends State<Myapp> {
@override
Widget build(BuildContext context) {
// TODO: implement build
return MaterialApp(
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Myhomepage(
title: "My Home Page",
),
);
}
}
class Myhomepage extends StatefulWidget {
final String title;
Myhomepage({this.title});
@override
_MyhomepageState createState() => _MyhomepageState();
}
class _MyhomepageState extends State<Myhomepage> {
int counter = 0;
@override
Widget build(BuildContext context) {
// TODO: implement build
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
centerTitle: true,
),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.add),
backgroundColor: Colors.grey[850],
onPressed: () {
setState(() {
counter++;
});
}),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
RaisedButton(
child: Text(
"Increase",
),
color: Colors.green,
onPressed: () {
setState(() {
counter++;
});
},
),
Text("The count of press button:"),
Text(
"$counter",
style: Theme.of(context).textTheme.display2.copyWith(color: counter<=0 ? Colors.red : Colors.blue)
),
RaisedButton(
child: Text(
"Decrease",
),
color: Colors.red,
onPressed: () {
setState(() {
counter--;
});
},
),
],
),
),
);
}
}
这是我的结果:
这是您实现所需系统的一种方法。我刚刚做了一个 returns 所需颜色的函数。
class _MyhomepageState extends State<Myhomepage> {
int counter = 0;
Color _getCounterColor() {
if (counter > 0) return Colors.blue;
else if (counter < 0) return Colors.red;
else return Colors.green;
}
@override
Widget build(BuildContext context) {
// TODO: implement build
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
centerTitle: true,
),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.add),
backgroundColor: Colors.grey[850],
onPressed: () {
setState(() {
counter++;
});
}),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
RaisedButton(
child: Text(
"Increase",
),
color: Colors.green,
onPressed: () {
setState(() {
counter++;
});
},
),
Text("The count of press button:"),
Text(
"$counter",
style: Theme.of(context).textTheme.display2.copyWith(color: _getCounterColor()),
),
RaisedButton(
child: Text(
"Decrease",
),
color: Colors.red,
onPressed: () {
setState(() {
counter--;
});
},
),
],
),
),
);
}
}