user-interface - 当文本在 Flutter 中溢出时如何使 Text 小部件像选取框一样

Question

我正在寻找一种在 Text 小部件上实现 Marquee 样式的方法，以便在文本从屏幕溢出时自动开始滚动。有没有办法做到这一点。我已经尝试了所有的装饰模式，但似乎无法在那里找到 Marquee 选项。

Answer 1

这个小部件是我想出的，我认为它可以满足您的需求:

class MarqueeWidget extends StatefulWidget {
  final Widget child;
  final Axis direction;
  final Duration animationDuration, backDuration, pauseDuration;

  const MarqueeWidget({
    Key? key,
    required this.child,
    this.direction = Axis.horizontal,
    this.animationDuration = const Duration(milliseconds: 6000),
    this.backDuration = const Duration(milliseconds: 800),
    this.pauseDuration = const Duration(milliseconds: 800),
  }) : super(key: key);

  @override
  _MarqueeWidgetState createState() => _MarqueeWidgetState();
}

class _MarqueeWidgetState extends State<MarqueeWidget> {
  late ScrollController scrollController;

  @override
  void initState() {
    scrollController = ScrollController(initialScrollOffset: 50.0);
    WidgetsBinding.instance!.addPostFrameCallback(scroll);
    super.initState();
  }

  @override
  void dispose() {
    scrollController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
      child: widget.child,
      scrollDirection: widget.direction,
      controller: scrollController,
    );
  }

  void scroll(_) async {
    while (scrollController.hasClients) {
      await Future.delayed(widget.pauseDuration);
      if (scrollController.hasClients) {
        await scrollController.animateTo(
          scrollController.position.maxScrollExtent,
          duration: widget.animationDuration,
          curve: Curves.ease,
        );
      }
      await Future.delayed(widget.pauseDuration);
      if (scrollController.hasClients) {
        await scrollController.animateTo(
          0.0,
          duration: widget.backDuration,
          curve: Curves.easeOut,
        );
      }
    }
  }
}

它的功能应该很明显。示例实现如下所示:

class FlutterMarqueeText extends StatefulWidget {
  const FlutterMarqueeText({Key? key}) : super(key: key);

  @override
  _FlutterMarqueeTextState createState() => _FlutterMarqueeTextState();
}

class _FlutterMarqueeTextState extends State<FlutterMarqueeText> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Flutter Marquee Text"),
      ),
      body: const Center(
        child: SizedBox(
          width: 200.0,
          child: MarqueeWidget(
            direction: Axis.horizontal,
            child: Text("This text is to long to be shown in just one line"),
          ),
        ),
      ),
    );
  }
}