Hey, I published flutter_animated_button plugin in pub.dev. You can implement button animated easily by using this plugin. Check this plugin and share it. Please share your feedback so i can implement and improve it.If you want to add some other animation then you can request me or create PR for it.
Pub.dev : https://pub.dev/packages/flutter_animated_button
Github repos. :https://github.com/NikhilVadoliya/FlutterAnimatedButton