flutter_typeahead 0.1.0

A highly customizable typeahead text input field

example/lib/main.dart

import 'dart:async';
import 'dart:math';

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'flutter_typeahead demo',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  
  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: 2,
      child: Scaffold(
        appBar: AppBar(
          title: TabBar(
              tabs: [
                Tab(
                  text: 'Example 1: Navigation',
                ),
                Tab(
                    text: 'Example 2: Form'
                )
              ]
          ),
        ),
        body: TabBarView(
          children: [
            NavigationExample(),
            FormExample()
          ]
        )
      ),
    );
  }
}

class NavigationExample extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: EdgeInsets.all(32.0),
      child: Column(
        children: <Widget>[
          Text(
            'What are you looking for?'
          ),
          SizedBox(height: 10.0,),
          TypeAheadField(
            autofocus: true,
            style: DefaultTextStyle.of(context).style.copyWith(
              fontStyle: FontStyle.italic
            ),
            decoration: InputDecoration(
              border: OutlineInputBorder()
            ),
            suggestionsCallback: (pattern) async {
              return await BackendService.getSuggestions(pattern);
            },
            itemBuilder: (context, suggestion) {
              return ListTile(
                leading: Icon(Icons.shopping_cart),
                title: Text(suggestion['name']),
                subtitle: Text('\$${suggestion['price']}'),
              );
            },
            onSuggestionSelected: (suggestion) {
              Navigator.of(context).push(MaterialPageRoute(
                builder: (context) => ProductPage(product: suggestion)
              ));
            },
          ),
        ],
      ),
    );
  }
}

class FormExample extends StatefulWidget {
  @override
  _FormExampleState createState() => _FormExampleState();
}

class _FormExampleState extends State<FormExample> {

  final GlobalKey<FormState> _formKey = GlobalKey<FormState>();
  final TextEditingController _typeAheadController = TextEditingController();

  String _selectedCity;

  @override
  Widget build(BuildContext context) {
    return Form(
      key: this._formKey,
      child: Padding(
        padding: EdgeInsets.all(32.0),
        child: Column(
          children: <Widget>[
            Text(
              'What is your favorite city?'
            ),
            TypeAheadFormField(
              controller: this._typeAheadController,
              decoration: InputDecoration(
                labelText: 'City'
              ),
              suggestionsCallback: (pattern) {
                return CitiesService.getSuggestions(pattern);
              },
              itemBuilder: (context, suggestion) {
                return ListTile(
                  title: Text(suggestion),
                );
              },
              transitionBuilder: (context, suggestionsBox, controller) {
                return suggestionsBox;
              },
              onSuggestionSelected: (suggestion) {
                this._typeAheadController.text = suggestion;
              },
              validator: (value) {
                if (value.isEmpty) {
                  return 'Please select a city';
                }
              },
              onSaved: (value) => this._selectedCity = value,
            ),
            SizedBox(height: 10.0,),
            RaisedButton(
              child: Text('Submit'),
              onPressed: () {
                if (this._formKey.currentState.validate()) {
                  this._formKey.currentState.save();
                  Scaffold.of(context).showSnackBar(SnackBar(
                    content: Text('Your Favorite City is ${this._selectedCity}')
                  ));
                }
              },
            )
          ],
        ),
      ),
    );
  }
}


class ProductPage extends StatelessWidget {

  final Map<String, dynamic> product;

  ProductPage({this.product});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Padding(
        padding: const EdgeInsets.all(50.0),
        child: Column(
          children: [
            Text(
              this.product['name'],
              style: Theme.of(context).textTheme.headline,
            ),
            Text(
              this.product['price'].toString() + ' USD',
              style: Theme.of(context).textTheme.subhead,
            )
          ],
        ),
      ),
    );
  }
}


class BackendService {
  static Future<List> getSuggestions(String query) async {
    await Future.delayed(Duration(seconds: 1));

    return List.generate(3, (index) {
      return {
        'name': query + index.toString(),
        'price': Random().nextInt(100)
      };
    });
  }
}

class CitiesService {

  static final cities = [
    'Beirut',
    'Damascus',
    'San Fransisco',
    'Rome',
    'Los Angeles',
    'Madrid',
    'Bali',
    'Barcelona',
    'Paris',
    'Bucharest'
  ];

  static getSuggestions(String query) {
    final cities = CitiesService.cities;

    cities.sort((a, b) {
      return CitiesService._distance(query, a) - CitiesService._distance(query, b);
    });

    return cities.take(4).toList();
  }

  // source: https://github.com/kseo/edit_distance/blob/master/lib/src/levenshtein.dart
  static int _distance(String s1, String s2) {
    if (s1 == s2) {
      return 0;
    }

    if (s1.length == 0) {
      return s2.length;
    }

    if (s2.length == 0) {
      return s1.length;
    }

    List<int> v0 = new List<int>(s2.length + 1);
    List<int> v1 = new List<int>(s2.length + 1);
    List<int> vtemp;

    for (var i = 0; i < v0.length; i++) {
      v0[i] = i;
    }

    for (var i = 0; i < s1.length; i++) {
      v1[0] = i + 1;

      for (var j = 0; j < s2.length; j++) {
        int cost = 1;
        if (s1.codeUnitAt(i) == s2.codeUnitAt(j)) {
          cost = 0;
        }
        v1[j + 1] = min(v1[j] + 1, min(v0[j + 1] + 1, v0[j] + cost));
      }

      vtemp = v0;
      v0 = v1;
      v1 = vtemp;
    }

    return v0[s2.length];
  }
}