primarySwatch
时间: 2023-11-24 17:53:03 浏览: 23
primarySwatch是一个MaterialColor类型的值,它是Flutter中的一个主题颜色,用于为Material系列组件提供基础色。与primaryColor不同,primarySwatch可以接收颜色的0x进制(16进制)和常用的颜色属性。在Flutter中,我们可以通过在ThemeData中设置primarySwatch来更改应用程序的主题颜色。例如,以下代码将主题颜色更改为黄色:
```dart
theme: ThemeData(
primarySwatch: Colors.amber,
),
```
这将把主题颜色更改为黄色,并将其应用于Material系列组件,例如AppBar和FloatingActionButton等。
相关问题
flutter中gridview代码示例
当然,我可以给你一个简单的Flutter中GridView的代码示例。以下是一个基本的GridView示例:
```dart
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'GridView Example',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(),
);
}
}
class MyHomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('GridView Example'),
),
body: GridView.count(
crossAxisCount: 2, // 每行显示的列数
children: List.generate(10, (index) {
return Container(
margin: EdgeInsets.all(10),
color: Colors.blue,
child: Center(
child: Text(
'Item $index', style: TextStyle(
color: Colors.white,
fontSize: 20,
),
),
),
);
}),
),
);
}
}
```
这个示例中,我们使用了`GridView.count`来创建一个网格布局,每行显示2列。通过`List.generate`方法生成了10个网格项,每个网格项都是一个带有文本的蓝色容器。
flutter 清除缓存
在Flutter中清除缓存可以通过以下步骤实现[^1]:
1. 导入`path_provider`包:
```dart
import 'package:path_provider/path_provider.dart';
```
2. 获取缓存目录:
```dart
Directory cacheDir = await getTemporaryDirectory();
```
3. 计算缓存大小:
```dart
int cacheSize = 0;
List<FileSystemEntity> files = cacheDir.listSync(recursive: true);
for (FileSystemEntity file in files) {
if (file is File) {
cacheSize += await file.length();
}
}
```
4. 删除缓存文件:
```dart
for (FileSystemEntity file in files) {
if (file is File) {
await file.delete(recursive: true);
}
}
```
下面是一个完整的示例代码:
```dart
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:path_provider/path_provider.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Cache Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(),
);
}
}
class MyHomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Flutter Cache Demo'),
),
body: Center(
child: RaisedButton(
child: Text('Clear Cache'),
onPressed: () async {
Directory cacheDir = await getTemporaryDirectory();
int cacheSize = 0;
List<FileSystemEntity> files = cacheDir.listSync(recursive: true);
for (FileSystemEntity file in files) {
if (file is File) {
cacheSize += await file.length();
}
}
for (FileSystemEntity file in files) {
if (file is File) {
await file.delete(recursive: true);
}
}
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: Text('Cache Cleared'),
content: Text('Cache size: ${cacheSize ~/ 1024} KB'),
actions: <Widget>[
FlatButton(
child: Text('OK'),
onPressed: () {
Navigator.of(context).pop();
},
),
],
);
},
);
},
),
),
);
}
}
```