如何为可扩展的 Flutter 小部件制作动画以将其滑出屏幕

Question

我有两个可扩展的按钮排成一行，占据了所有屏幕宽度。在左键单击时，我希望左键占据整个屏幕宽度，而右键则通过右侧显示消失在屏幕之外。这是我迄今为止取得的成就：

正如你所注意到的，当没有足够的空间来渲染它时，右边的按钮会在最后被压扁。我只是想让它继续移出屏幕而不改变它的宽度。我可以通过为按钮设置一行文本来实现这一点，但我希望该解决方案通常适用于所有小部件（看起来右边有足够的空间来渲染它）。

当前解决方案：

import 'package:flutter/material.dart';

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

class TestAnimation extends StatefulWidget {
  @override
  _TestAnimationState createState() => _TestAnimationState();
}

class _TestAnimationState extends State<TestAnimation> with SingleTickerProviderStateMixin {
  AnimationController _animationController;
  Animation _animation;

  @override
  void initState() {
    super.initState();
    _animationController = AnimationController(duration: Duration(seconds: 2), vsync: this);
    _animation = IntTween(begin: 100, end: 0).animate(_animationController);
    _animation.addListener(() => setState(() {}));
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Row(
            children: <Widget>[
              Expanded(
                flex: 100,
                child: OutlineButton(
                  child: Text("Left"),
                  onPressed: () {
                    if (_animationController.value == 0.0) {
                      _animationController.forward();
                    } else {
                      _animationController.reverse();
                    }
                  },
                ),
              ),
              Expanded(
                flex: _animation.value,
                // Uses to hide widget when flex is going to 0
                child: SizedBox(
                  width: 0,
                  child: OutlineButton(
                    child: Text(
                      "Right",
                    ),
                    onPressed: () {},
                  ),
                ),
              )
            ],
          ),
        ),
      ),
    );
  }
}

Answer 1

更新：定义TextOverflow文本小部件的其他方式。

Expanded(
                flex: _animation.value,
                // Uses to hide widget when flex is going to 0
                child: SizedBox(
                  width: 0.0,
                  child: OutlineButton(
                    child: Text(
                      "Right",
                      overflow: TextOverflow.ellipsis, // Add this
                    ),
                    onPressed: () {},
                  ),
                ),
              )

这个（右键被压扁）可以在FittedBox小部件的帮助下解决。

import 'package:flutter/material.dart';

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

class TestAnimation extends StatefulWidget {
  @override
  _TestAnimationState createState() => _TestAnimationState();
}

class _TestAnimationState extends State<TestAnimation> with SingleTickerProviderStateMixin {
  AnimationController _animationController;
  Animation _animation;

  @override
  void initState() {
    super.initState();
    _animationController = AnimationController(duration: Duration(seconds: 2), vsync: this);
    _animation = IntTween(begin: 100, end: 0).animate(_animationController);
    _animation.addListener(() => setState(() {}));
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Row(
            children: <Widget>[
              Expanded(
                flex: 100,
                child: OutlineButton(
                  child: Text("Left"),
                  onPressed: () {
                    if (_animationController.value == 0.0) {
                      _animationController.forward();
                    } else {
                      _animationController.reverse();
                    }
                  },
                ),
              ),
              Expanded(
                flex: _animation.value,
                // Uses to hide widget when flex is going to 0
                child: SizedBox(
                  width: 0.0,
                  child: OutlineButton(
                    child: FittedBox(    //Add this
                      child: Text(
                        "Right",
                      ),
                    ),
                    onPressed: () {},
                  ),
                ),
              )
            ],
          ),
        ),
      ),
    );
  }
}

输出：