lightweight-flutter-animations

name	lightweight-flutter-animations
description	Learn how to create a streamlined animation widget in Flutter that eliminates the need for `setState` by leveraging an abstract class and `SingleTickerProviderStateMixin` for efficient UI updates.
metadata	{"url":"https://rodydavis.com/posts/snippets/lightweight-flutter-animations","last_modified":"Tue, 03 Feb 2026 20:04:28 GMT"}

Lightweight Flutter Animations

Overview 

First we need to create the abstract class:

abstract class AnimationWidget<T extends StatefulWidget> extends State<T>
    with SingleTickerProviderStateMixin {
  Duration elapsed = Duration.zero;
  Duration delta = Duration.zero;
  late final Ticker ticker;
  BoxConstraints constraints = const BoxConstraints.tightFor();

  @override
  void initState() {
    super.initState();
    ticker = createTicker((elapsed) {
      delta = elapsed - this.elapsed;
      this.elapsed = elapsed;
      update(elapsed);
      if (mounted) setState(() {});
    });
    ticker.start();
    WidgetsBinding.instance.addPostFrameCallback(start);
  }

  @override
  void dispose() {
    ticker.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(builder: (context, dimens) {
      constraints = dimens;
      return paint(context, dimens);
    });
  }

  void start(Duration time) {}

  void update(Duration time);

  Widget paint(BuildContext context, BoxConstraints constraints);
}

This will let us replace State with AnimationWidget and not need to call setState to rebuild the ui.

Example 

For the example we need an inline canvas painter:

class InlinePainter extends CustomPainter {
  InlinePainter({
    required this.draw,
    super.repaint,
  });

  final void Function(Canvas canvas, Size size) draw;

  @override
  void paint(Canvas canvas, Size size) {
    draw(canvas, size);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) => true;
}