Flutter颜色生成插件rainbow_color的使用
Flutter颜色生成插件rainbow_color的使用
简介
rainbow_color 是一个用于简化数值域到多色范围插值的Flutter插件。它接受一个数值域（即开始和结束数字）和两个或更多颜色组成的光谱，并提供列表访问操作符 [] 以进行插值。
该包还提供了 RainbowColorTween，这是标准 ColorTween 的多色变体，消除了为等权重转换构建更复杂的 TweenSequence 的需求。
使用方法
插值颜色
要在一个光谱中插值颜色，可以使用列表访问操作符：
import 'package:rainbow_color/rainbow_color.dart';
void main() {
var rb = Rainbow(
spectrum: [Color(0xFFFF0000), Color(0xFFFFFFFF), Color(0xff00ff00)],
rangeStart: -10,
rangeEnd: 10,
);
Color warmColor = rb[-9.32];
Color coldColor = rb[8.44];
}
使用 RainbowColorTween
在动画中使用 RainbowColorTween 来替代 ColorTween，以便在多个颜色之间进行插值：
@override
void initState() {
super.initState();
_controller = AnimationController(duration: widget.duration, vsync: this);
_clAnim = RainbowColorTween([Color(0x33FFAAAA), Color(0x33000000), Color(0x00000000)])
.animate(_controller)
..addListener(() {
setState(() {});
});
}
示例代码
以下是一个完整的示例代码，展示了如何在Flutter应用中使用 rainbow_color 插件：
import 'package:flutter/material.dart';
import 'package:rainbow_color/rainbow_color.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Rainbow Color Demo'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key? key, required this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> with SingleTickerProviderStateMixin {
late Animation<double> animation;
late AnimationController controller;
final Rainbow _rb = Rainbow(
spectrum: const [
Colors.red,
Colors.orange,
Colors.yellow,
Colors.green,
Colors.blue,
Colors.indigo,
Colors.purple,
Colors.red,
],
rangeStart: 0.0,
rangeEnd: 300.0,
);
@override
void initState() {
super.initState();
controller = AnimationController(duration: const Duration(seconds: 5), vsync: this);
animation = Tween<double>(begin: _rb.rangeStart.toDouble(), end: _rb.rangeEnd.toDouble())
.animate(controller)
..addStatusListener((status) {
if (status == AnimationStatus.completed) {
controller.reset();
controller.forward();
} else if (status == AnimationStatus.dismissed) {
controller.forward();
}
});
controller.forward();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
ColorCycler(),
],
),
),
);
}
@override
void dispose() {
controller.dispose();
super.dispose();
}
}
class ColorCycler extends StatefulWidget {
@override
_ColorCyclerState createState() => _ColorCyclerState();
}
class _ColorCyclerState extends State<ColorCycler> with SingleTickerProviderStateMixin {
late Animation<double> animation;
late AnimationController controller;
final Rainbow _rb = Rainbow(
spectrum: const [
Colors.red,
Colors.orange,
Colors.yellow,
Colors.green,
Colors.blue,
Colors.indigo,
Colors.purple,
Colors.red,
],
rangeStart: 0.0,
rangeEnd: 300.0,
);
@override
void initState() {
super.initState();
controller = AnimationController(duration: const Duration(seconds: 5), vsync: this);
animation = Tween<double>(begin: _rb.rangeStart.toDouble(), end: _rb.rangeEnd.toDouble())
.animate(controller)
..addStatusListener((status) {
if (status == AnimationStatus.completed) {
controller.reset();
controller.forward();
} else if (status == AnimationStatus.dismissed) {
controller.forward();
}
});
controller.forward();
}
@override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.all(8.0),
child: AnimatedBuilder(
animation: animation,
builder: (BuildContext context, _) => Column(
children: <Widget>[
ColorText(),
Container(
height: 250.0,
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topLeft,
end: Alignment.bottomRight,
colors: [
_rb[animation.value],
_rb[(50.0 + animation.value) % _rb.rangeEnd]
]),
border: Border.all(
color: Colors.black,
width: 4,
),
borderRadius: BorderRadius.circular(12),
),
child: Padding(
padding: const EdgeInsets.all(24.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
GreyScaleCycler(
baseColor: _rb[animation.value],
duration: const Duration(seconds: 5),
text: "Foo"),
GreyScaleCycler(
baseColor: _rb[(50.0 + animation.value) % _rb.rangeEnd],
duration: const Duration(seconds: 8),
text: "Bar",
leftToRight: false),
],
),
),
),
Padding(
padding: const EdgeInsets.fromLTRB(8.0, 0, 8.0, 0),
child: Container(
height: 50.0,
child: new Column(
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: List.generate(10, (index) => index / 10)
.map((s) => Container(
height: 45.0,
width: 30.0,
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
colors: [
Rainbow(spectrum: [
_rb[animation.value],
_rb[(50.0 + animation.value) % _rb.rangeEnd]
])[s],
Color(0xffffff)
]),
)))
.toList(),
),
],
),
),
),
],
),
),
);
}
@override
void dispose() {
controller.dispose();
super.dispose();
}
}
class ColorText extends StatefulWidget {
@override
_ColorTextState createState() => _ColorTextState();
}
class _ColorTextState extends State<ColorText> with SingleTickerProviderStateMixin {
late AnimationController controller;
late Animation<Color> _colorAnim;
@override
void initState() {
super.initState();
controller = AnimationController(duration: Duration(seconds: 3), vsync: this);
_colorAnim = RainbowColorTween([Colors.blue, Colors.green, Colors.red, Colors.blue])
.animate(controller)
..addListener(() {
setState(() {});
})
..addStatusListener((status) {
if (status == AnimationStatus.completed) {
controller.reset();
controller.forward();
} else if (status == AnimationStatus.dismissed) {
controller.forward();
}
});
controller.forward();
}
@override
Widget build(BuildContext context) {
return Text("Hello!", style: TextStyle(color: _colorAnim.value));
}
@override
void dispose() {
controller.dispose();
super.dispose();
}
}
class GreyScaleCycler extends StatefulWidget {
const GreyScaleCycler({
Key? key,
required this.baseColor,
required this.text,
required this.duration,
this.leftToRight = true,
}) : super(key: key);
final Color baseColor;
final Duration duration;
final bool leftToRight;
final String text;
static const List<Color> spectrum = [
Colors.white,
const Color(0x33ffffff),
const Color(0x33000000),
Colors.black,
const Color(0x33000000),
const Color(0x33ffffff),
Colors.white
];
@override
_GreyScaleCyclerState createState() => _GreyScaleCyclerState();
}
class _GreyScaleCyclerState extends State<GreyScaleCycler> with SingleTickerProviderStateMixin {
late AnimationController controller;
late Animation<Color> _bwAnim;
late Animation<Color> _wbAnim;
@override
void initState() {
super.initState();
controller = AnimationController(duration: widget.duration, vsync: this);
_wbAnim = RainbowColorTween(GreyScaleCycler.spectrum).animate(controller);
_bwAnim = RainbowColorTween(GreyScaleCycler.spectrum).animate(controller)
..addStatusListener((status) {
if (status == AnimationStatus.completed) {
controller.reset();
controller.forward();
} else if (status == AnimationStatus.dismissed) {
controller.forward();
}
});
controller.forward();
}
@override
Widget build(BuildContext context) {
return Container(
height: 55.0,
decoration: BoxDecoration(
gradient: LinearGradient(
colors: [widget.baseColor, _bwAnim.value],
begin: widget.leftToRight ? Alignment.centerLeft : Alignment.centerRight,
end: widget.leftToRight ? Alignment.centerRight : Alignment.centerLeft,
),
border: Border.all(
color: Colors.black87,
width: 4,
),
borderRadius: BorderRadius.circular(12),
),
child: SizedBox(
width: double.infinity,
child: Center(
child: Text(widget.text,
textAlign: TextAlign.center,
style: TextStyle(color: _wbAnim.value, fontSize: 24.0)),
),
),
);
}
@override
void dispose() {
controller.dispose();
super.dispose();
}
}
这个示例代码展示了如何在Flutter应用中使用 rainbow_color 插件来创建一个彩色渐变动画效果。你可以根据需要调整颜色光谱、动画持续时间和其他参数。
更多关于Flutter颜色生成插件rainbow_color的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html
1 回复
更多关于Flutter颜色生成插件rainbow_color的使用的实战系列教程也可以访问 https://www.itying.com/category-92-b0.html
当然，以下是一个关于如何使用Flutter颜色生成插件rainbow_color的代码案例。这个插件可以帮助你生成彩虹色渐变或其他基于彩虹色系的颜色。
首先，你需要在你的pubspec.yaml文件中添加rainbow_color依赖：
dependencies:
flutter:
sdk: flutter
rainbow_color: ^latest_version # 请替换为实际的最新版本号
然后，运行flutter pub get来获取依赖。
接下来，你可以在你的Flutter应用中使用这个插件来生成彩虹颜色。以下是一个简单的示例，展示了如何使用rainbow_color插件来生成颜色，并在一个容器中使用这些颜色：
import 'package:flutter/material.dart';
import 'package:rainbow_color/rainbow_color.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Rainbow Color Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: RainbowColorDemo(),
);
}
}
class RainbowColorDemo extends StatefulWidget {
@override
_RainbowColorDemoState createState() => _RainbowColorDemoState();
}
class _RainbowColorDemoState extends State<RainbowColorDemo> {
final int numberOfColors = 10; // 你想要生成的彩虹颜色数量
List<Color> rainbowColors = [];
@override
void initState() {
super.initState();
// 生成彩虹颜色
rainbowColors = generateRainbowColors(numberOfColors);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Rainbow Color Demo'),
),
body: GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
crossAxisSpacing: 10,
mainAxisSpacing: 10,
),
itemCount: rainbowColors.length,
itemBuilder: (context, index) {
return Container(
color: rainbowColors[index],
child: Center(
child: Text(
'Color ${index + 1}',
style: TextStyle(color: Colors.white),
),
),
);
},
),
);
}
// 使用rainbow_color插件生成彩虹颜色
List<Color> generateRainbowColors(int count) {
List<Color> colors = [];
for (int i = 0; i < count; i++) {
double ratio = i / (count - 1.0); // 计算当前颜色在彩虹中的比例
Color color = RainbowColor.fromRatio(ratio);
colors.add(color);
}
return colors;
}
}
在这个示例中，我们首先导入了rainbow_color包，然后在_RainbowColorDemoState类中，我们在initState方法中生成了一系列彩虹颜色。generateRainbowColors方法接受一个整数参数count，表示你想要生成的颜色数量，并返回一个颜色列表。我们使用RainbowColor.fromRatio方法来根据比例生成彩虹颜色。
在build方法中，我们使用GridView.builder来显示这些颜色。每个颜色都被显示在一个容器中，容器中心有一个显示颜色索引的文本。
请注意，实际使用中，RainbowColor.fromRatio方法可能需要根据rainbow_color插件的实际API进行调整。如果插件提供了不同的方法来生成颜色，你可能需要相应地修改代码。
希望这个示例对你有所帮助！
