When you want to add animations that don’t rebuild the entire widget tree, AnimatedBuilder is an efficient way to create smooth, high-performance animations.
Example: Rotating Icon Animation
This example shows how to use AnimatedBuilder to smoothly rotate an icon without rebuilding unnecessary parts of the widget tree:
import 'package:flutter/material.dart'; void main() { runApp(MyApp()); } class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( home: Scaffold( appBar: AppBar(title: Text("Rotating Icon")), body: Center(child: RotatingIcon()), ), ); } } class RotatingIcon extends StatefulWidget { @override _RotatingIconState createState() => _RotatingIconState(); } class _RotatingIconState extends State<RotatingIcon> with SingleTickerProviderStateMixin { late AnimationController _controller; @override void initState() { super.initState(); _controller = AnimationController( duration: const Duration(seconds: 2), vsync: this, )..repeat(); // Repeats indefinitely } @override void dispose() { _controller.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return AnimatedBuilder( animation: _controller, builder: (context, child) { return Transform.rotate( angle: _controller.value * 2.0 * 3.1416, // Full circle child: child, ); }, child: Icon( Icons.sync, size: 100, color: Colors.blue, ), ); } } Explanation
• AnimationController: Controls the animation’s duration and state (we set it to repeat indefinitely here).
• AnimatedBuilder: Efficiently rebuilds only the parts of the widget that need updating, keeping performance smooth.
• Transform.rotate: Rotates the icon based on the controller’s current animation value.
Using AnimatedBuilder like this is a highly efficient way to add animations to your Flutter app without rebuilding the widget tree, which keeps animations smooth and improves app performance.
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