comunicmobile/lib/ui/widgets/tablet_mode/appbar_custom_dropdown_widget.dart

import 'package:comunic/ui/widgets/icon_button_badge.dart';
import 'package:flutter/material.dart';

/// Custom dropdown built for Appbar
///
/// @author Pierre Hubert

const _overlay_w = 300.0;
const _overlay_h = 400.0;

class AppBarCustomDropDownWidget extends StatefulWidget {
  final Widget icon;
  final int notificationsBadge;
  final Widget Function(BuildContext) onBuildOverlay;

  const AppBarCustomDropDownWidget({
    Key key,
    @required this.icon,
    @required this.notificationsBadge,
    @required this.onBuildOverlay,
  })  : assert(icon != null),
        assert(notificationsBadge != null),
        assert(onBuildOverlay != null),
        super(key: key);

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

class _AppBarCustomDropDownWidgetState
    extends State<AppBarCustomDropDownWidget> {
  @override
  Widget build(BuildContext context) {
    return IconButtonWithBadge(
      icon: widget.icon,
      onPressed: toggleOverlay,
      number: widget.notificationsBadge,
    );
  }

  void toggleOverlay() async {
    RenderBox renderBox = context.findRenderObject();
    final size = renderBox.size;
    final offset = renderBox.localToGlobal(Offset(size.width, size.height));

    Navigator.of(context).push(_AppBarCustomPopupRoute(
      onBuild: widget.onBuildOverlay,
      showContext: context,
      offset: offset,
    ));
  }
}

class _AppBarCustomPopupRoute extends PopupRoute {
  final BuildContext showContext;
  final Widget Function(BuildContext) onBuild;
  final Offset offset;

  _AppBarCustomPopupRoute({
    @required this.showContext,
    @required this.onBuild,
    @required this.offset,
  });

  @override
  Color get barrierColor => null;

  @override
  bool get barrierDismissible => true;

  @override
  String get barrierLabel =>
      MaterialLocalizations.of(showContext).modalBarrierDismissLabel;

  @override
  Widget buildPage(BuildContext context, Animation<double> animation,
      Animation<double> secondaryAnimation) {
    return MediaQuery.removePadding(
      context: context,
      removeTop: true,
      removeBottom: true,
      removeLeft: true,
      removeRight: true,
      child: Builder(
        builder: (BuildContext context) {
          return _PopupContentBody(
            onBuild: onBuild,
            offset: offset,
          );
        },
      ),
    );
  }

  @override
  Duration get transitionDuration => Duration(milliseconds: 0);
}

class _PopupContentBody extends StatelessWidget {
  final Widget Function(BuildContext) onBuild;
  final Offset offset;

  const _PopupContentBody({Key key, this.onBuild, this.offset})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: <Widget>[
        GestureDetector(
          onTapDown: (d) => Navigator.of(context).pop(),
          onPanDown: (d) => Navigator.of(context).pop(),
          child: Container(color: Color(0x55000000)),
        ),
        Positioned(
          left: offset.dx - _overlay_w,
          top: offset.dy,
          width: _overlay_w,
          height: _overlay_h,
          child: Card(child: onBuild(context)),
        )
      ],
    );
  }
}