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A base line to code an overlay in flutter. like search overlay on Text-Field
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| // MIT License | |
| // | |
| // Copyright (c) 2023 Simon Lightfoot | |
| // | |
| // Permission is hereby granted, free of charge, to any person obtaining a copy | |
| // of this software and associated documentation files (the "Software"), to deal | |
| // in the Software without restriction, including without limitation the rights | |
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
| // copies of the Software, and to permit persons to whom the Software is | |
| // furnished to do so, subject to the following conditions: | |
| // | |
| // The above copyright notice and this permission notice shall be included in all | |
| // copies or substantial portions of the Software. | |
| // | |
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
| // SOFTWARE. | |
| // | |
| import 'dart:async'; | |
| import 'package:flutter/material.dart'; | |
| void main() { | |
| runApp(const App()); | |
| } | |
| class App extends StatelessWidget { | |
| const App({super.key}); | |
| @override | |
| Widget build(BuildContext context) { | |
| return const MaterialApp( | |
| home: Home(), | |
| ); | |
| } | |
| } | |
| class Home extends StatelessWidget { | |
| const Home({super.key}); | |
| @override | |
| Widget build(BuildContext context) { | |
| return const Scaffold( | |
| body: Padding( | |
| padding: EdgeInsets.symmetric(vertical: 8.0, horizontal: 24.0), | |
| child: SearchField(), | |
| ), | |
| ); | |
| } | |
| } | |
| class SearchField extends StatefulWidget { | |
| const SearchField({super.key}); | |
| @override | |
| State<SearchField> createState() => _SearchFieldState(); | |
| } | |
| class _SearchFieldState extends State<SearchField> { | |
| late final _controller = TextEditingController() | |
| ..addListener(_onFocusOrTextChanged); | |
| late final _focusNode = FocusNode()..addListener(_onFocusOrTextChanged); | |
| final LayerLink _layerLink = LayerLink(); | |
| OverlayEntry? _overlayEntry; | |
| final _widthNotifier = ValueNotifier(0.0); | |
| void _onFocusOrTextChanged() { | |
| if (!_focusNode.hasFocus || _controller.text.trim().isEmpty) { | |
| if (_overlayEntry == null) { | |
| return; | |
| } | |
| _overlayEntry?.remove(); | |
| _overlayEntry?.dispose(); | |
| _overlayEntry = null; | |
| return; | |
| } | |
| if (_overlayEntry != null) { | |
| return; | |
| } | |
| _overlayEntry = OverlayEntry( | |
| builder: (context) { | |
| return SearchSuggestions( | |
| controller: _controller, | |
| layerLink: _layerLink, | |
| width: _widthNotifier, | |
| ); | |
| }, | |
| ); | |
| Overlay.of(context)!.insert(_overlayEntry!); | |
| } | |
| @override | |
| void dispose() { | |
| _controller.removeListener(_onFocusOrTextChanged); | |
| _controller.dispose(); | |
| _focusNode.removeListener(_onFocusOrTextChanged); | |
| _focusNode.dispose(); | |
| _widthNotifier.dispose(); | |
| super.dispose(); | |
| } | |
| @override | |
| Widget build(BuildContext context) { | |
| return CompositedTransformTarget( | |
| link: _layerLink, | |
| child: LayoutBuilder( | |
| builder: (BuildContext context, BoxConstraints constraints) { | |
| scheduleMicrotask(() => _widthNotifier.value = constraints.maxWidth); | |
| return TextField( | |
| controller: _controller, | |
| focusNode: _focusNode, | |
| ); | |
| }, | |
| ), | |
| ); | |
| } | |
| } | |
| class SearchSuggestions extends StatefulWidget { | |
| final TextEditingController controller; | |
| final LayerLink layerLink; | |
| final ValueNotifier<double> width; | |
| const SearchSuggestions({ | |
| Key? key, | |
| required this.controller, | |
| required this.layerLink, | |
| required this.width, | |
| }) : super(key: key); | |
| @override | |
| State<SearchSuggestions> createState() => _SearchSuggestionsState(); | |
| } | |
| class _SearchSuggestionsState extends State<SearchSuggestions> { | |
| @override | |
| void initState() { | |
| widget.controller.addListener(_onTextChanged); | |
| super.initState(); | |
| } | |
| @override | |
| void dispose() { | |
| widget.controller.removeListener(_onTextChanged); | |
| super.dispose(); | |
| } | |
| late var _text = widget.controller.text; | |
| void _onTextChanged() { | |
| setState(() { | |
| _text = widget.controller.text; | |
| }); | |
| } | |
| @override | |
| Widget build(BuildContext context) { | |
| return CompositedTransformFollower( | |
| link: widget.layerLink, | |
| followerAnchor: Alignment.topLeft, | |
| targetAnchor: Alignment.bottomLeft, | |
| child: Align( | |
| alignment: Alignment.topLeft, | |
| child: Builder(builder: (context) { | |
| return ValueListenableBuilder<double>( | |
| valueListenable: widget.width, | |
| builder: (context, width, child) { | |
| return SizedBox( | |
| width: width, | |
| // height: 200, | |
| child: Material( | |
| type: MaterialType.card, | |
| child: SingleChildScrollView( | |
| child: Column( | |
| children: [ | |
| InkWell( | |
| onTap: () {}, | |
| child: ListTile( | |
| title: Text(_text), | |
| ), | |
| ), | |
| ], | |
| ), | |
| ), | |
| ), | |
| ); | |
| }, | |
| ); | |
| }), | |
| ), | |
| ); | |
| } | |
| } | |
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