Continuously playing a Looping Animation https://pub.dev/packages/rive

MyRiveWidget.dart

import 'package:flutter/services.dart';
import 'package:rive/rive.dart';
import 'package:flutter/material.dart';

class MyRiveWidget extends StatefulWidget {
  final String riveFile;
  final String animationName;
  final BoxFit fit;

  const MyRiveWidget({
    Key key,
    @required this.riveFile,
    @required this.animationName,
    this.fit,
  }) : super(key: key);
  @override
  MyRiveWidgetState createState() => MyRiveWidgetState();
}

class MyRiveWidgetState extends State<MyRiveWidget> {
  //bool get isPlaying => _controller?.isActive ?? false;
  Artboard riveArtboard;
  RiveAnimationController _controller;
  @override
  void initState() {
    super.initState();
    rootBundle.load(widget.riveFile).then(
      (data) async {
        final file = RiveFile();
        // Load the RiveFile from the binary data.
        if (file.import(data)) {
          // The artboard is the root of the animation and gets drawn in the
          // Rive widget.
          final artboard = file.mainArtboard;
          // Add a controller to play back a known animation on the main/default
          // artboard.We store a reference to it so we can toggle playback.
          artboard.addController(_controller = SimpleAnimation(widget.animationName));
          setState(() => riveArtboard = artboard);
        }
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return riveArtboard == null
        ? const SizedBox()
        : Rive(
            fit: widget.fit ?? BoxFit.cover,
            artboard: riveArtboard,
          );
  }
}