in this current library options i don't know how can i set optional start animation, for example when i click on floating action button begin of start animation is zero, how can i set for example Offset.zero to another offset?

Doesn't pass child directly to builder method of AnimatedBuilder instead pass child to AnimatedBuilder and take it from argument of builder method. This improves performance as child is not rebuild on every frame.

import 'package:circular_reveal_animation/circular_reveal_animation.dart';
import 'package:flutter/material.dart';

class HiveTubeSliverAppBar extends StatefulWidget {
  final Function _onTap;

  const HiveTubeSliverAppBar({@required Function onTap}) : _onTap = onTap;

  @override
  _HiveTubeSliverAppBarState createState() => _HiveTubeSliverAppBarState();
}

class _HiveTubeSliverAppBarState extends State<HiveTubeSliverAppBar> with TickerProviderStateMixin {
  AnimationController _animationController;
  Animation<double> _animation;

  AnimationController _circularAnimationController;
  Animation<double> _circularAnimation;

  @override
  void initState() {
    super.initState();

    _animationController = AnimationController(vsync: this, duration: const Duration(milliseconds: 250));
    _animation = Tween<double>(begin: 0.0, end: 1.0).animate(_animationController);

    _circularAnimationController = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 1000),
    );
    _circularAnimation = CurvedAnimation(
      parent: _circularAnimationController,
      curve: Curves.easeIn,
    );
  }

  @override
  Widget build(BuildContext context) {
    return SliverPersistentHeader(
      pinned: false,
      floating: true,
      delegate: CustomAutoHideAppBarDelegate(
        child: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 12.0),
          child: Row(
            children: <Widget>[

              IconButton(icon: const Icon(Icons.more_vert_rounded), onPressed: () => _showOverlayHomeMenu(context, _animationController,_circularAnimation))

            ],
          ),
        ),
      ),
    );
  }

  Future<void> _showOverlayHomeMenu(BuildContext context, AnimationController animationController, Animation<double> circularAnimation) async {
    final OverlayState _overlayState = Overlay.of(context);
    final OverlayEntry _overlayEntry = OverlayEntry(builder: (context) {
      return CircularRevealAnimation(
        animation: circularAnimation,
        centerOffset: const Offset(10, 10),
        child: Positioned(
          top: kToolbarHeight - 20,
          right: 20.0,
          child: Opacity(
              opacity: _animationController.value,
              child: Card(
                elevation: 8.0,
                shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8.0)),
                color: const Color(0xFF32313C),
                child: Container(
                  width: 200.0,
                  height: 250.0,
                  child: const ListTile(
                    title: Text(
                      'aaaaaaa',
                      style: TextStyle(color: Colors.white),
                    ),
                    leading: Icon(
                      Icons.assessment,
                      color: Colors.white,
                    ),
                  ),
                ),
              ),
            ),
        ),
      );
    });

    _animationController.addListener(() {
      _overlayState.setState(() {});
    });

    _overlayState.insert(_overlayEntry);
    _animationController.forward();
    await Future.delayed(const Duration(milliseconds: 3500));
    _animationController.reverse();

    _overlayEntry.remove();
  }
}

Hi thank you for your awesome work! However I think you need to update the license to include the year and the author name. I need the copyright notice to be included in one of my repo here since I use one of your works in it.

how can i use this library for flutter dialogs?

import 'package:circular_reveal_animation/circular_reveal_animation.dart';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'CRA Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage>
    with SingleTickerProviderStateMixin {
  AnimationController animationController;
  Animation<double> animation;

  @override
  void initState() {
    super.initState();
    animationController = AnimationController(
      vsync: this,
      duration: Duration(milliseconds: 1000),
    );
    animation = CurvedAnimation(
      parent: animationController,
      curve: Curves.easeIn,
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("CRA Demo"),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Center(
          child: CircularRevealAnimation(
            child: FutureBuilder(
              future: showDialog(),
            ),
            animation: animation,
            center: Offset(130, 100),
//            minRadius: 12,
//          maxRadius: 200,
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(onPressed: () {
        if (animationController.status == AnimationStatus.forward ||
            animationController.status == AnimationStatus.completed) {
          animationController.reverse();
        } else {
          animationController.forward();
        }
      }),
    );
  }
  Future<void> showDialog()async{
    bool _fromTop = false;
    showGeneralDialog(
      barrierLabel: "Label",
      barrierDismissible: true,
      barrierColor: Colors.black.withOpacity(0.5),
      transitionDuration: Duration(milliseconds: 700),
      context: context,
      pageBuilder: (context, anim1, anim2) {
        return Align(
          alignment: _fromTop ? Alignment.topCenter : Alignment.bottomCenter,
          child: Container(
            height: 300,
            child: SizedBox.expand(child: FlutterLogo()),
            margin: EdgeInsets.only(top: 50, left: 12, right: 12, bottom: 50),
            decoration: BoxDecoration(
              color: Colors.white,
              borderRadius: BorderRadius.circular(40),
            ),
          ),
        );
      },
      transitionBuilder: (context, anim1, anim2, child) {
        return SlideTransition(
          position: Tween(begin: Offset(0, _fromTop ? -1 : 1), end: Offset(0, 0)).animate(anim1),
          child: child,
        );
      },
    );
  }
}

Is it possible to attach the reveal to a controller so that if you swipe or pull a slider it reveals? Like slide to the right to reveal and then slide to the left and it closes back up. Slide half way and it reveals half. Thanks