Flutter Animate

https://pub.dev/packages/flutter_animate
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Flutter Animate is a performant library that makes it simple to add animated effects and builders in...
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### Pubspec.yaml Dependency

Source: https://pub.dev/packages/flutter_animate/install

This is an example of how the flutter_animate dependency will appear in your pubspec.yaml file after running `flutter pub add`.

```yaml
dependencies:
  flutter_animate: ^4.5.2
```

--------------------------------

### Initialize Flutter Animate Example Application

Source: https://pub.dev/packages/flutter_animate/example

Sets up the main entry point for the demo application, including shader loading and the navigation structure for different animation views.

```dart
import 'dart:ui';

import 'package:example/examples/everything_view.dart';
import 'package:flutter/material.dart';

import 'examples/adapter_view.dart';
import 'examples/info_view.dart';
import 'examples/playground_view.dart';
import 'examples/visual_view.dart';

void main() {
  runApp(const MyApp());
  _loadShader(); // this is a touch hacky, but works for now.
}

Future<void> _loadShader() async {
  return FragmentProgram.fromAsset('assets/shaders/shader.frag').then(
      (FragmentProgram prgm) {
    EverythingView.shader = prgm.fragmentShader();
  }, onError: (Object error, StackTrace stackTrace) {
    FlutterError.reportError(
        FlutterErrorDetails(exception: error, stack: stackTrace));
  });
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Flutter Animate Demo',
      debugShowCheckedModeBanner: false,
      home: FlutterAnimateExample(),
    );
  }
}

// this is a very quick and dirty example.
class FlutterAnimateExample extends StatefulWidget {
  const FlutterAnimateExample({Key? key}) : super(key: key);

  static final List<TabInfo> tabs = [
    TabInfo(Icons.info_outline, (_) => InfoView(key: UniqueKey()), 'Info',
        'Simple example of Widget & List animations.'),
    TabInfo(Icons.palette_outlined, (_) => VisualView(key: UniqueKey()),
        'Visual', 'Visual effects like saturation, tint, & blur.'),
    TabInfo(Icons.format_list_bulleted, (_) => const AdapterView(), 'Adapters',
        'Animations driven by scrolling & user input.'),
    TabInfo(Icons.grid_on_outlined, (_) => const EverythingView(),
        'Kitchen Sink', 'Grid view of effects with default settings.'),
    TabInfo(Icons.science_outlined, (_) => PlaygroundView(key: UniqueKey()),
        'Playground', 'A blank canvas for experimenting.'),
  ];

  @override
  State<FlutterAnimateExample> createState() => _FlutterAnimateExampleState();
}

class _FlutterAnimateExampleState extends State<FlutterAnimateExample> {
  int _viewIndex = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: const Color(0xFF404349),
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: _viewIndex,
        selectedFontSize: 12,
        unselectedFontSize: 12,
        selectedItemColor: const Color(0xFF80DDFF),
        unselectedItemColor: const Color(0x998898A0),
        showSelectedLabels: false,
        showUnselectedLabels: false,
        type: BottomNavigationBarType.fixed,
        backgroundColor: const Color(0xFF2A2B2F),
        elevation: 0,
        onTap: (index) => setState(() => _viewIndex = index),
        items: [
          for (final tab in FlutterAnimateExample.tabs)
            BottomNavigationBarItem(
              icon: Icon(tab.icon),
              label: tab.label,
            )
        ],
      ),
      body: DefaultTextStyle(
        style: const TextStyle(
          color: Color(0xFFCCCDCF),
          fontSize: 14,
          height: 1.5,
        ),
        child: SafeArea(
          bottom: false,
          child: FlutterAnimateExample.tabs[_viewIndex].builder(context),
        ),
      ),
    );
  }
}

class TabInfo {
  const TabInfo(this.icon, this.builder, this.label, this.description);

  final IconData icon;
  final WidgetBuilder builder;
  final String label;
  final String description;
}
```

--------------------------------

### Import flutter_animate

Source: https://pub.dev/packages/flutter_animate/install

Import the flutter_animate package into your Dart code to start using its animation features.

```dart
import 'package:flutter_animate/flutter_animate.dart';
```

--------------------------------

### Configure Effect Begin and End Values

Source: https://pub.dev/packages/flutter_animate

Specify begin and end parameters to define the start and end states of an effect.

```dart
// an opacity of 1 is "neutral"
Text("Hello").animate().fade() // begin=0, end=1
Text("Hello").animate().fade(begin: 0.5) // end=1
Text("Hello").animate().fade(end: 0.5) // begin=1
```

--------------------------------

### Listen to Animation Value

Source: https://pub.dev/packages/flutter_animate

Use ListenEffect to register a callback that receives the animation's current value (0.0 to 1.0). This example prints the opacity value during a fade-in.

```dart
Text("Hello").animate().fadeIn(curve: Curves.easeOutExpo)
  .listen(callback: (value) => print('current opacity: $value'))
```

--------------------------------

### Add Callback Halfway Through Animation

Source: https://pub.dev/packages/flutter_animate

Use CallbackEffect to trigger a function at a specific point in an animation. This example adds a callback halfway through a fade-in effect.

```dart
Text("Hello").animate().fadeIn(duration: 600.ms)
  .callback(duration: 300.ms, callback: (_) => print('halfway'))
```

--------------------------------

### Animate Based on State Changes

Source: https://pub.dev/packages/flutter_animate

Set a target value on the Animate widget to make it react to state changes. This example fades and scales a button based on a boolean `_over` variable.

```dart
MyButton().animate(target: _over ? 1 : 0)
  .fade(end: 0.8).scaleXY(end: 1.1)
```

--------------------------------

### Configure Animation Delay and Looping

Source: https://pub.dev/packages/flutter_animate

Use the Animate delay parameter for initial delays and onPlay for controller callbacks like looping.

```dart
Text("Hello").animate(
    delay: 1000.ms, // this delay only happens once at the very start
    onPlay: (controller) => controller.repeat(), // loop
  ).fadeIn(delay: 500.ms) // this delay happens at the start of each loop
```

--------------------------------

### Apply Effects with Extension Method

Source: https://pub.dev/packages/flutter_animate

Use the .animate() extension method on any widget for a shorthand, chainable syntax.

```dart
Text("Hello World!").animate().fade().scale()
```

--------------------------------

### Configure Delay and Duration

Source: https://pub.dev/packages/flutter_animate

Control animation timing by specifying delay and duration parameters for individual effects.

```dart
Text("Hello").animate()
  .fade(duration: 500.ms)
  .scale(delay: 500.ms) // runs after fade.
```

--------------------------------

### Add flutter_animate Dependency

Source: https://pub.dev/packages/flutter_animate/install

Run this command in your terminal to add the flutter_animate package to your Flutter project. This command automatically updates your pubspec.yaml file.

```bash
$ flutter pub add flutter_animate
```

--------------------------------

### Animate Lists with AnimateList

Source: https://pub.dev/packages/flutter_animate

Use AnimateList or the .animate() extension on a list of widgets to apply staggered effects.

```dart
Column(children: AnimateList(
  interval: 400.ms,
  effects: [FadeEffect(duration: 300.ms)],
  children: [Text("Hello"), Text("World"),  Text("Goodbye")],
))
```

```dart
Column(
  children: [Text("Hello"), Text("World"),  Text("Goodbye")]
    .animate(interval: 400.ms).fade(duration: 300.ms),
)
```

--------------------------------

### Apply Shaders with ShaderEffect

Source: https://pub.dev/packages/flutter_animate

Integrate GLSL fragment shaders into the animation chain.

```dart
myWidget.animate()
  .shader(duration: 2.seconds, shader: myShader)
  .fadeIn(duration: 300.ms) // shader can be combined with other effects
```

--------------------------------

### Apply Effect Parameters

Source: https://pub.dev/packages/flutter_animate

Pass additional parameters to effects to customize their behavior.

```dart
Text('Hello').animate().tint(color: Colors.purple)
```

--------------------------------

### Handle Animation Events

Source: https://pub.dev/packages/flutter_animate

Use callbacks like onPlay to access the AnimationController for manual control.

```dart
Text("Horrible Pulsing Text")
  .animate(onPlay: (controller) => controller.repeat(reverse: true))
  .fadeOut(curve: Curves.easeInOut)
```

--------------------------------

### Create Custom Effects with CustomEffect

Source: https://pub.dev/packages/flutter_animate

Implement custom animation logic using a builder function that receives the current animation value.

```dart
Text("Hello World").animate().custom(
  duration: 300.ms,
  builder: (context, value, child) => Container(
    color: Color.lerp(Colors.red, Colors.blue, value),
    padding: EdgeInsets.all(8),
    child: child, // child is the Text widget being animated
  )
)
```

```dart
Animate().custom(
  duration: 10.seconds,
  begin: 10,
  end: 0,
  builder: (_, value, __) => Text(value.round()),
).fadeOut()
```

--------------------------------

### Missing Type Annotation in Adapter

Source: https://pub.dev/packages/flutter_animate/score

This code snippet highlights a missing type annotation in the `_tick` method within `lib/src/adapters/adapter.dart`. Ensure type annotations are present for static analysis.

```dart
   ╷
84 │   void _tick(_) {
   │              ^
   ╵

```

--------------------------------

### Apply Effects with Animate Widget

Source: https://pub.dev/packages/flutter_animate

Use the Animate widget to wrap a target widget and define a list of effects.

```dart
Animate(
  effects: [FadeEffect(), ScaleEffect()],
  child: Text("Hello World!"),
)
```

--------------------------------

### Swap Widgets with SwapEffect

Source: https://pub.dev/packages/flutter_animate

Replace the target widget at a specific time or reset animation sequences.

```dart
Text("Before").animate()
  .swap(duration: 900.ms, builder: (_, __) => Text("After"))
```

```dart
text.animate().fadeOut(300.ms) // fade out & then...
  // swap in original widget & fade back in via a new Animate:
  .swap(builder: (_, child) => child.animate().fadeIn())
```

--------------------------------

### Inherit Animation Parameters

Source: https://pub.dev/packages/flutter_animate

Effects inherit duration and delay from previous effects if not explicitly defined.

```dart
Text("Hello World!").animate()
  .fadeIn() // uses `Animate.defaultDuration`
  .scale() // inherits duration from fadeIn
  .move(delay: 300.ms, duration: 600.ms) // runs after the above w/new duration
  .blurXY() // inherits the delay & duration from move
```

--------------------------------

### Missing Type Annotation in Animate

Source: https://pub.dev/packages/flutter_animate/score

This code snippet points out a missing type annotation for the `status` parameter in the `_handleAnimationStatus` method within `lib/src/animate.dart`. Add type annotations for better code clarity and static analysis.

```dart
    ╷
369 │   void _handleAnimationStatus(status) {
    │                               ^^^^^^ 
    ╵

```

--------------------------------

### Sequence Effects with ThenEffect

Source: https://pub.dev/packages/flutter_animate

Use the then method to sequence effects relative to the end time of the previous effect.

```dart
Text("Hello").animate()
  .fadeIn(duration: 600.ms)
  .then(delay: 200.ms) // baseline=800ms
  .slide()
```

--------------------------------

### Toggle State with ToggleEffect

Source: https://pub.dev/packages/flutter_animate

Use ToggleEffect to switch between boolean states based on animation duration.

```dart
Animate().toggle(
  duration: 2.seconds,
  builder: (_, value, __) => Text(value ? "Before" : "After"),
)
```

```dart
Animate().toggle(
  duration: 1.ms,
  builder: (_, value, __) => AnimatedContainer(
    duration: 1.seconds,
    color: value ? Colors.red : Colors.green,
  ),
)
```

--------------------------------

### Reuse Immutable Effects

Source: https://pub.dev/packages/flutter_animate

Define global collections of immutable Effect instances to maintain consistency across a design system.

```dart
MyGlobalEffects.transitionIn = <Effect>[
  FadeEffect(duration: 100.ms, curve: Curves.easeOut),
  ScaleEffect(begin: 0.8, curve: Curves.easeIn)
]

// then:
Text('Hello').animate(effects: MyGlobalEffects.transitionIn)
```

--------------------------------

### Callback After Animation Completes

Source: https://pub.dev/packages/flutter_animate

CallbackEffect inherits duration and delay from previous effects. This snippet executes a callback once a scale animation is finished.

```dart
Text("Hello").animate().scale(delay: 200.ms, duration: 400.ms)
  .callback(callback: (_) => print('scale is done'))
```
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