使用堆栈时如何将文本编辑器移至屏幕底部？

Question

有人知道为什么我似乎无法将文本输入框（_buildTextComposer（））移到页面底部吗？我已经尝试了所有方法，但似乎无法正常使用...

谢谢！

我认为它主要在这段代码中，但是我在下面包括了所有代码：

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Stack(children: <Widget>[
        _buildIamge(),
        _buildTopHeader(),
       Container(
         alignment: Alignment.center,
            child: new ListView.builder(
          padding: new EdgeInsets.all(8.0),
          reverse: true,
          itemBuilder: (_, int index) => _messages[index],
          itemCount: _messages.length,
        )),
        Container(
          decoration: new BoxDecoration(color: Theme.of(context).cardColor),
          height: 50.0,
          child: _buildTextComposer(),
          alignment: Alignment.bottomCenter,
        ),
      ]),
      resizeToAvoidBottomPadding:false,
    );
  }
}

这里是它的外观图片：App Example

import 'package:flutter/material.dart';
import 'package:flutter_dialogflow/dialogflow_v2.dart';

double _imageHeight = 256.0;

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

class Olivia extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Example Dialogflow Flutter',
      theme: new ThemeData(
        primarySwatch: Colors.deepOrange,
      ),
      debugShowCheckedModeBanner: false,
      home: new HomePageDialogflow(),
    );
  }
}

class HomePageDialogflow extends StatefulWidget {
  HomePageDialogflow({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _HomePageDialogflow createState() => new _HomePageDialogflow();
}

class _HomePageDialogflow extends State<HomePageDialogflow> {
  final List<ChatMessage> _messages = <ChatMessage>[];
  final TextEditingController _textController = new TextEditingController();

  Widget _buildTextComposer() {
    return new IconTheme(
      data: new IconThemeData(color: Theme.of(context).accentColor),
      child: new Container(
        margin: const EdgeInsets.symmetric(horizontal: 8.0),
        child: new Row(
          children: <Widget>[
            new Flexible(
              child: new TextField(
                controller: _textController,
                onSubmitted: _handleSubmitted,
                decoration:
                    new InputDecoration.collapsed(hintText: "Send a message"),
              ),
            ),
            new Container(
              margin: new EdgeInsets.symmetric(horizontal: 4.0),
              child: new IconButton(
                  icon: new Icon(Icons.send),
                  onPressed: () => _handleSubmitted(_textController.text)),
            ),
          ],
        ),
      ),
    );
  }

  void Response(query) async {
    _textController.clear();
    AuthGoogle authGoogle =
        await AuthGoogle(fileJson: "assets/credentials.json")
            .build();
    Dialogflow dialogflow =
        Dialogflow(authGoogle: authGoogle, language: Language.english);
    AIResponse response = await dialogflow.detectIntent(query);
    ChatMessage message = new ChatMessage(
      text: response.getMessage() ??
          new CardDialogflow(response.getListMessage()[0]).title,
      name: "Bot",
      type: false,
    );
    setState(() {
      _messages.insert(0, message);
    });
  }

  void _handleSubmitted(String text) {
    _textController.clear();
    ChatMessage message = new ChatMessage(
      text: text,
      name: "Promise",
      type: true,
    );
    setState(() {
      _messages.insert(0, message);
    });
    Response(text);
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Stack(children: <Widget>[
        _buildIamge(),
        _buildTopHeader(),
       Container(
         alignment: Alignment.center,
            child: new ListView.builder(
          padding: new EdgeInsets.all(8.0),
          reverse: true,
          itemBuilder: (_, int index) => _messages[index],
          itemCount: _messages.length,
        )),
        Container(
          decoration: new BoxDecoration(color: Theme.of(context).cardColor),
          height: 50.0,
          child: _buildTextComposer(),
          alignment: Alignment.bottomCenter,
        ),
      ]),
      resizeToAvoidBottomPadding:false,
    );
  }
}

class Conatiner {
}

class ChatMessage extends StatelessWidget {
  ChatMessage({this.text, this.name, this.type});

  final String text;
  final String name;
  final bool type;

  List<Widget> otherMessage(context) {
    return <Widget>[
      new Container(
        margin: const EdgeInsets.only(right: 16.0),
        child: new CircleAvatar(child: new Text('B')),
      ),
      new Expanded(
        child: new Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            new Text(this.name,
                style: new TextStyle(fontWeight: FontWeight.bold)),
            new Container(
              margin: const EdgeInsets.only(top: 5.0),
              child: new Text(text),
            ),
          ],
        ),
      ),
    ];
  }

  List<Widget> myMessage(context) {
    return <Widget>[
      new Expanded(
        child: new Column(
          crossAxisAlignment: CrossAxisAlignment.end,
          children: <Widget>[
            new Text(this.name, style: Theme.of(context).textTheme.subhead),
            new Container(
              margin: const EdgeInsets.only(top: 5.0),
              child: new Text(text),
            ),
          ],
        ),
      ),
      new Container(
        margin: const EdgeInsets.only(left: 16.0),
        child: new CircleAvatar(
            child: new Text(
          this.name[0],
          style: new TextStyle(fontWeight: FontWeight.bold),
        )),
      ),
    ];
  }

  @override
  Widget build(BuildContext context) {
    return new Container(
      margin: const EdgeInsets.symmetric(vertical: 10.0),
      child: new Row(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: this.type ? myMessage(context) : otherMessage(context),
      ),
    );
  }
}

Widget _buildIamge() {
    return new ClipPath(
      clipper: new DialogonalClipper(),
      child: new Image.asset(
        'assets/Header.png',
        fit: BoxFit.cover,
        height: _imageHeight,
    ),
    );
  }


class DialogonalClipper extends CustomClipper<Path> {
  @override
  Path getClip(Size size) {
    Path path = new Path();
    path.lineTo(0.0, size.height - 120.0);
    path.lineTo(size.width, size.height-170);
    path.lineTo(size.width, 0.0);
    path.close();
    return path;
  }

  @override
  bool shouldReclip(CustomClipper<Path> oldClipper) => true;
}

Widget _buildTopHeader() {
  return new Padding(
    padding: new EdgeInsets.only(left: 16.0, top: 70.5),
    child: new Row(
      children: <Widget>[
        new Padding(
          padding: const EdgeInsets.only(left: 5.0),
          child: new Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              new Text(
                'Olivia',
                style: new TextStyle(
                    fontSize: 30.0,
                    color: Colors.white,
                    fontWeight: FontWeight.w700),
              ),
            ],
          ),
        ),
      ],
    ),
  );
}

Answer 1

只需按照以下方法更改构建方法，

@override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Column(
          children: <Widget>[
            Expanded(
              child: Stack(children: <Widget>[
                _buildIamge(),
                _buildTopHeader(),
                Container(
                    alignment: Alignment.center,
                    child: new ListView.builder(
                      padding: new EdgeInsets.all(8.0),
                      reverse: true,
                      itemBuilder: (_, int index) => _messages[index],
                      itemCount: _messages.length,
                    )),
              ]),
            ),
            Container(
              decoration:
              new BoxDecoration(color: Theme.of(context).cardColor),
              height: 50.0,
              child: _buildTextComposer(),
              alignment: Alignment.bottomCenter,
            ),
          ],
        ),
      ),
    );
  }

将堆栈窗口小部件放入列中并将其包装在其中将提供_buildTextComposer（）所需的空间，并将其设置在页面底部。