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ExpandableBottomSheet

This is a BottomSheet with a draggable height like the Google Maps App on Android.

If you have suggestions or find bugs please write an issue at github. PR's are welcome.

Arguments

Argument	Description
expandableContent	This is the widget which you can hide and show by dragging. It has to be a widget with a constant height.
background	This is the widget behind the expandableContent which holds usually the content of your page.
persistentHeader	This is a Widget which is on top of the expandableContent and will never be hidden. It is made for a widget which indicates the user he can expand the content by dragging.
persistentFooter	This is a widget which is always shown at the bottom. The expandableContentis if it is expanded on top of it so you don't need margin to see all of your content. You can use it for example for navigation or a menu.
persistentContentHeight	This is the height of the content which will never been contracted. It only relates to expandableContent. persistentHeader and persistentFooter will not be affected by this.
animationDurationExtend	This is the duration for the animation if you stop dragging with high speed.
animationDurationContract	is the duration for the animation to bottom if you stop dragging with high speed. If it is null animationDurationExtend will be used.
animationCurveExpand	This is the curve of the animation for expanding the expandableContent if the drag ended with high speed.
animationCurveContract	This is the curve of the animation for contracting the expandableContent if the drag ended with high speed.
onIsExtendedCallback	This will be executed if the extend reaches its maximum.
onIsContractedCallback	This will be executed if the extend reaches its minimum.
enableToggle	This will enable tap to toggle option on header.
isDraggable	This will make the ExpandableBottomSheet draggable by the user or not.

Examples

This are two examples how to use the ExpandableBottomSheet

Import Library

import 'package:expandable_bottom_sheet/expandable_bottom_sheet.dart';

Easy Example

ExpandableBottomSheet(
  background: Container(
    color: Colors.red,
    child: Center(
      child: Text('Background'),
    ),
  ),
  persistentHeader: Container(
    height: 40,
    color: Colors.blue,
    child: Center(
      child: Text('Header'),
    ),
  ),
  expandableContent: Container(
    height: 500,
    color: Colors.green,
    child: Center(
      child: Text('Content'),
    ),
  ),
);

Call expand, contract, or status programmatically

...
GlobalKey<ExpandableBottomSheetState> key = new GlobalKey();
...

@override
Widget build(BuildContext context) {
  return ExpandableBottomSheet(
    key: key
    ...
  );
}

void expand() => key.currentState.expand();

void contract() key.currentState.contract();

ExpansionStatus status() => key.currentState.expansionStatus;

Expert Example

class ExampleExpert extends StatefulWidget {
  @override
  _ExampleExpertState createState() => _ExampleExpertState();
}

class _ExampleExpertState extends State<ExampleExpert> {
  GlobalKey<ExpandableBottomSheetState> key = new GlobalKey();
  int _contentAmount = 0;
  ExpansionStatus _expansionStatus = ExpansionStatus.contracted;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text(_expansionStatus.toString()),
        ),
        body: ExpandableBottomSheet(
          //use the key to get access to expand(), contract() and expansionStatus
          key: key,

          //optional
          //callbacks (use it for example for an animation in your header)
          onIsContractedCallback: () => print('contracted'),
          onIsExtendedCallback: () => print('extended'),

          //optional; default: Duration(milliseconds: 250)
          //The durations of the animations.
          animationDurationExtend: Duration(milliseconds: 500),
          animationDurationContract: Duration(milliseconds: 250),

          //optional; default: Curves.ease
          //The curves of the animations.
          animationCurveExpand: Curves.bounceOut,
          animationCurveContract: Curves.ease,

          //optional
          //The content extend will be at least this height. If the content
          //height is smaller than the persistentContentHeight it will be
          //animated on a height change.
          //You can use it for example if you have no header.
          persistentContentHeight: 220,

          //required
          //This is the widget which will be overlapped by the bottom sheet.
          background: Container(
            color: Colors.blue[800],
          ),

          //optional
          //This widget is sticking above the content and will never be contracted.
          persistentHeader: Container(
            color: Colors.orange,
            constraints: BoxConstraints.expand(height: 40),
            child: Center(
              child: Container(
                height: 8.0,
                width: 50.0,
                color: Color.fromARGB((0.25 * 255).round(), 0, 0, 0),
              ),
            ),
          ),

          //required
          //This is the content of the bottom sheet which will be extendable by dragging.
          expandableContent: Container(
            constraints: BoxConstraints(maxHeight: 400),
            child: SingleChildScrollView(
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: <Widget>[
                  for (int i = 0; i < _contentAmount; i++)
                    Container(
                      height: 50,
                      color: Colors.red[((i % 8) + 1) * 100],
                    ),
                ],
              ),
            ),
          ),

          //optional
          //This is a widget aligned to the bottom of the screen and stays there.
          //You can use this for example for navigation.
          persistentFooter: Container(
            color: Colors.green,
            height: 100,
            child: Row(
              mainAxisSize: MainAxisSize.max,
              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
              children: <Widget>[
                IconButton(
                  icon: Icon(Icons.add),
                  onPressed: () => setState(() {
                    _contentAmount++;
                  }),
                ),
                IconButton(
                  icon: Icon(Icons.arrow_upward),
                  onPressed: () => setState(() {
                    key.currentState!.expand();
                  }),
                ),
                IconButton(
                  icon: Icon(Icons.cloud),
                  onPressed: () => setState(() {
                    _expansionStatus = key.currentState!.expansionStatus;
                  }),
                ),
                IconButton(
                  icon: Icon(Icons.arrow_downward),
                  onPressed: () => setState(() {
                    key.currentState!.contract();
                  }),
                ),
                IconButton(
                  icon: Icon(Icons.remove),
                  onPressed: () => setState(() {
                    if (_contentAmount > 0) _contentAmount--;
                  }),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}