How to create a scroll view with fixed footer with Flutter?

Question

I would like to create a view that has to have a Column with a scroll view (e.g. something like SingleChildScrollView) and a footer regardless of the screen size. If the screen is big enough, it will use the empty space between the scroll and the footer, if not, it will expand and only make the widget above the footer scrollable.

It's more or less like Listview with scrolling Footer at the bottom but with a diference that I want the keyboard to overflow the footer and it also should stay in place.

Something like

return Scaffold(
      body: Column(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: <Widget>[
          SingleChildScrollView(
            child: Padding(
              padding: const EdgeInsets.only(left: 30.0, right: 30.0, top: 80.0),
              child: Form(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: <Widget>[
                   // Multiple widgets and form fields
                  ],
                ),
              ),
            ),
          ),
          Padding(
            padding: const EdgeInsets.only(top: 50.0),
            child: SafeArea(
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: <Widget>[
                  // Footer widgets
                ],
              ),
            ),
          )
        ],
      ),
    );

Answer 1

For those who were looking to implement just footer with scrollview in a simple way, below code might help :

Scaffold(
      appBar: buildAppBar('Some cool appbar'),
      body: Column(
        children: [
          Expanded(
            child: SingleChildScrollView(
              child: Column(
                children: [
                  PackageCard(),
                  PackageCard(),
                  PackageCard(),
                ],
              ),
            ),
          ),
          Container(
            child: Text('Your super cool Footer'),
            color: Colors.amber,
          )
        ],
      ),
    );

Visual representation:-

---Column
    |
    |---Expanded--
                 |-SingleChildScrollView (column /YOUR SCROLLABLE VIEW)
    |
    |-Container(YOUR FOOTER)

I used expanded with SinglechildScrollView over here

Answer 2

The difficulty is that Column and SingleChildScrollView have a hard time working together because one needs constraints and the other removes them.

The trick is to use a CustomMultiChildLayout and do the calculations yourself. Helped by MediaQuery to obtain the size of the keyboard, so that the footer can disappear to leave more room for the content.

Here's a reusable widget that does it for you:

class FooterLayout extends StatelessWidget {
  const FooterLayout({
    Key key,
    @required this.body,
    @required this.footer,
  }) : super(key: key);

  final Container body;
  final Container footer;

  @override
  Widget build(BuildContext context) {
    return CustomMultiChildLayout(
      delegate: _FooterLayoutDelegate(MediaQuery.of(context).viewInsets),
      children: <Widget>[
        LayoutId(
          id: _FooterLayout.body,
          child: body,
        ),
        LayoutId(
          id: _FooterLayout.footer,
          child: footer,
        ),
      ],
    );
  }
}

enum _FooterLayout {
  footer,
  body,
}

class _FooterLayoutDelegate extends MultiChildLayoutDelegate {
  final EdgeInsets viewInsets;

  _FooterLayoutDelegate(this.viewInsets);

  @override
  void performLayout(Size size) {
    size = Size(size.width, size.height + viewInsets.bottom);
    final footer =
        layoutChild(_FooterLayout.footer, BoxConstraints.loose(size));

    final bodyConstraints = BoxConstraints.tightFor(
      height: size.height - max(footer.height, viewInsets.bottom),
      width: size.width,
    );

    final body = layoutChild(_FooterLayout.body, bodyConstraints);

    positionChild(_FooterLayout.body, Offset.zero);
    positionChild(_FooterLayout.footer, Offset(0, body.height));
  }

  @override
  bool shouldRelayout(MultiChildLayoutDelegate oldDelegate) {
    return true;
  }
}

Used as such:

FooterLayout(
  body: body,
  footer: footer,
),