animated_value_builder.dart

class AnimatedValueBuilder<T> extends StatefulWidget {
  const AnimatedValueBuilder({
    super.key,
    required this.duration,
    required this.tween,
    required this.progress,
    required this.builder,
    this.child,
  }) : assert(progress >= 0 && progress <= 1);

  final Duration duration;
  final Tween<T> tween;
  final double progress;

  final ValueWidgetBuilder<T> builder;
  final Widget? child;

  @override
  State<AnimatedValueBuilder<T>> createState() => _AnimatedValueBuilderState();
}

class _AnimatedValueBuilderState<T> extends State<AnimatedValueBuilder<T>>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller = AnimationController(
    value: widget.progress,
    duration: widget.duration,
    vsync: this,
  );

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

  @override
  void didUpdateWidget(covariant AnimatedValueBuilder<T> oldWidget) {
    super.didUpdateWidget(oldWidget);
    _controller.duration = widget.duration;
    if (widget.progress != oldWidget.progress) {
      _controller.animateTo(widget.progress);
    }
  }

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _controller,
      builder: (context, child) =>
          widget.builder(context, widget.tween.evaluate(_controller), child),
      child: widget.child,
    );
  }
}