flutter_sticky_header 0.4.0

Flutter implementation of sticky headers as a sliver. Use it in a CustomScrollView.

example/lib/main.dart

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Sticky Header example',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new MainScreen(),
    );
  }
}

class MainScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new SimpleScaffold(
      title: 'Flutter Sticky Header example',
      child: new Builder(builder: (BuildContext context) {
        return new CustomScrollView(
          slivers: _buildSlivers(context),
        );
      }),
    );
  }

  List<Widget> _buildSlivers(BuildContext context) {
    List<Widget> slivers = new List<Widget>();

    //slivers.add(_buildExample());
    //slivers.add(_buildBuilderExample());
    int i = 0;
    slivers.add(SliverAppBar(
      backgroundColor: Colors.blue.withOpacity(0.5),
      title: Text('text'),
      pinned: true,
    ));
    slivers.add(SliverAppBar(
      backgroundColor: Colors.yellow.withOpacity(0.5),
      title: Text('text'),
      pinned: true,
    ));
    slivers.addAll(_buildHeaderBuilderLists(context, i, i += 5));
    slivers.addAll(_buildLists(context, i, i += 3));
    slivers.addAll(_buildGrids(context, i, i += 3));
    slivers.addAll(_buildSideHeaderGrids(context, i, i += 3));
    slivers.addAll(_buildHeaderBuilderLists(context, i, i += 5));
    return slivers;
  }

  List<Widget> _buildLists(BuildContext context, int firstIndex, int count) {
    return List.generate(count, (sliverIndex) {
      sliverIndex += firstIndex;
      return new SliverStickyHeader(
        header: _buildHeader(sliverIndex),
        sliver: new SliverList(
          delegate: new SliverChildBuilderDelegate(
            (context, i) => new ListTile(
                  leading: new CircleAvatar(
                    child: new Text('$sliverIndex'),
                  ),
                  title: new Text('List tile #$i'),
                ),
            childCount: 4,
          ),
        ),
      );
    });
  }

  List<Widget> _buildHeaderBuilderLists(
      BuildContext context, int firstIndex, int count) {
    return List.generate(count, (sliverIndex) {
      sliverIndex += firstIndex;
      return new SliverStickyHeaderBuilder(
        builder: (context, state) =>
            _buildAnimatedHeader(context, sliverIndex, state),
        sliver: new SliverList(
          delegate: new SliverChildBuilderDelegate(
            (context, i) => new ListTile(
                  leading: new CircleAvatar(
                    child: new Text('$sliverIndex'),
                  ),
                  title: new Text('List tile #$i'),
                ),
            childCount: 4,
          ),
        ),
      );
    });
  }

  List<Widget> _buildGrids(BuildContext context, int firstIndex, int count) {
    return List.generate(count, (sliverIndex) {
      sliverIndex += firstIndex;
      return new SliverStickyHeader(
        header: _buildHeader(sliverIndex),
        sliver: new SliverGrid(
          gridDelegate: new SliverGridDelegateWithFixedCrossAxisCount(
              crossAxisCount: 3, crossAxisSpacing: 4.0, mainAxisSpacing: 4.0),
          delegate: new SliverChildBuilderDelegate(
            (context, i) => GestureDetector(
                  onTap: () => Scaffold.of(context).showSnackBar(
                      new SnackBar(content: Text('Grid tile #$i'))),
                  child: new GridTile(
                    child: Card(
                      child: new Container(
                        color: Colors.green,
                      ),
                    ),
                    footer: new Container(
                      color: Colors.white.withOpacity(0.5),
                      child: Padding(
                        padding: const EdgeInsets.all(8.0),
                        child: new Text(
                          'Grid tile #$i',
                          style: const TextStyle(color: Colors.black),
                        ),
                      ),
                    ),
                  ),
                ),
            childCount: 9,
          ),
        ),
      );
    });
  }

  List<Widget> _buildSideHeaderGrids(
      BuildContext context, int firstIndex, int count) {
    return List.generate(count, (sliverIndex) {
      sliverIndex += firstIndex;
      return new SliverStickyHeader(
        overlapsContent: true,
        header: _buildSideHeader(context, sliverIndex),
        sliver: new SliverPadding(
          padding: new EdgeInsets.only(left: 60.0),
          sliver: new SliverGrid(
            gridDelegate: new SliverGridDelegateWithFixedCrossAxisCount(
                crossAxisCount: 3,
                crossAxisSpacing: 4.0,
                mainAxisSpacing: 4.0,
                childAspectRatio: 1.0),
            delegate: new SliverChildBuilderDelegate(
              (context, i) => GestureDetector(
                    onTap: () => Scaffold.of(context).showSnackBar(
                        new SnackBar(content: Text('Grid tile #$i'))),
                    child: new GridTile(
                      child: Card(
                        child: new Container(
                          color: Colors.orange,
                        ),
                      ),
                      footer: new Container(
                        color: Colors.white.withOpacity(0.5),
                        child: Padding(
                          padding: const EdgeInsets.all(8.0),
                          child: new Text(
                            'Grid tile #$i',
                            style: const TextStyle(color: Colors.black),
                          ),
                        ),
                      ),
                    ),
                  ),
              childCount: 12,
            ),
          ),
        ),
      );
    });
  }

  Widget _buildHeader(int index, {String text}) {
    return new Container(
      height: 60.0,
      color: Colors.lightBlue,
      padding: EdgeInsets.symmetric(horizontal: 16.0),
      alignment: Alignment.centerLeft,
      child: new Text(
        text ?? 'Header #$index',
        style: const TextStyle(color: Colors.white),
      ),
    );
  }

  Widget _buildSideHeader(BuildContext context, int index, {String text}) {
    return Padding(
      padding: const EdgeInsets.symmetric(horizontal: 8.0, vertical: 4.0),
      child: Align(
        alignment: Alignment.centerLeft,
        child: new SizedBox(
          height: 44.0,
          width: 44.0,
          child: GestureDetector(
            onTap: () => Scaffold
                .of(context)
                .showSnackBar(new SnackBar(content: Text('$index'))),
            child: new CircleAvatar(
              backgroundColor: Colors.orangeAccent,
              foregroundColor: Colors.white,
              child: new Text('$index'),
            ),
          ),
        ),
      ),
    );
  }

  Widget _buildAnimatedHeader(
      BuildContext context, int index, SliverStickyHeaderState state) {
    return GestureDetector(
      onTap: () => Scaffold
          .of(context)
          .showSnackBar(new SnackBar(content: Text('$index'))),
      child: new Container(
        height: 60.0,
        color: (state.isPinned ? Colors.pink : Colors.lightBlue)
            .withOpacity(1.0 - state.scrollPercentage),
        padding: EdgeInsets.symmetric(horizontal: 16.0),
        alignment: Alignment.centerLeft,
        child: new Text(
          'Header #$index',
          style: const TextStyle(color: Colors.white),
        ),
      ),
    );
  }

  Widget _buildExample() {
    return new SliverStickyHeader(
      header: new Container(
        height: 60.0,
        color: Colors.lightBlue,
        padding: EdgeInsets.symmetric(horizontal: 16.0),
        alignment: Alignment.centerLeft,
        child: new Text(
          'Header #0',
          style: const TextStyle(color: Colors.white),
        ),
      ),
      sliver: new SliverList(
        delegate: new SliverChildBuilderDelegate(
          (context, i) => new ListTile(
                leading: new CircleAvatar(
                  child: new Text('0'),
                ),
                title: new Text('List tile #$i'),
              ),
          childCount: 4,
        ),
      ),
    );
  }

  Widget _buildBuilderExample() {
    return new SliverStickyHeaderBuilder(
      builder: (context, state) => new Container(
            height: 60.0,
            color: (state.isPinned ? Colors.pink : Colors.lightBlue)
                .withOpacity(1.0 - state.scrollPercentage),
            padding: EdgeInsets.symmetric(horizontal: 16.0),
            alignment: Alignment.centerLeft,
            child: new Text(
              'Header #1',
              style: const TextStyle(color: Colors.white),
            ),
          ),
      sliver: new SliverList(
        delegate: new SliverChildBuilderDelegate(
          (context, i) => new ListTile(
                leading: new CircleAvatar(
                  child: new Text('0'),
                ),
                title: new Text('List tile #$i'),
              ),
          childCount: 4,
        ),
      ),
    );
  }
}

class SimpleScaffold extends StatelessWidget {
  const SimpleScaffold({
    Key key,
    this.title,
    this.child,
  }) : super(key: key);

  final String title;

  final Widget child;

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text(title),
      ),
      body: child,
    );
  }
}