Flutter 如何在颤振中实现多个倒计时进度条？

如何实现instagram顶部的故事进度条。如果存在多个故事，则为多个条形图；如果只有一个故事，则为一个条形图。10秒的计时器。到目前为止，我所做的工作还不错，但当有两个或更多快照时，它就不起作用了

代码

我试着把它放到列表视图中，但它有点不起作用

更新：

我想出了一个“Row.builder”的黑客，但我如何才能动画的进展？我使用的是计时器解决方案，我可以在计时器结束时更改快照，但进度条是否正确更新才是问题所在

Row(
  mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  children: List.generate(widget.posts.length, (index) {
    if (this._index == index) {
      return Expanded(
        child: Container(
          padding: EdgeInsets.symmetric(horizontal: 10.0),
          height: 30,
          child: CustomPaint(
            foregroundPainter: ProgressPainter(value: this._countDown.remainingTime.inSeconds / 10.0),
          ),
        ),
      );
    } else {
      return Expanded(
        child: Container(
          padding: EdgeInsets.symmetric(horizontal: 10.0),
          height: 30,
          child: CustomPaint(
            foregroundPainter: ProgressPainter(value: 0.0),
          ),
        ),
      );
    }
  }).reversed.toList(),
)

注: 我有进度条工作的效果，但只有一个。我有两个帖子，但只有一个进度条有效，另一个为0。

解决了这个问题

倒计时：

int _index = 0;
CountDown _countDown;
StreamSubscription _countDownSubscription;

@override
void initState() {
  super.initState();
  this._initTimer();
}

_initTimer() {
  if (mounted)
    setState(() {
      this._countDown = CountDown(Duration(seconds: widget.posts[this._index].timer));
      this._countDown.remainingTime = Duration(seconds: widget.posts[this._index].timer);
      this._countDownSubscription = this._countDown.stream.listen(null);
    });

  this._countDownSubscription.onData((d) {
    setState(() {}); // Updates the UI to animate the progress bar
  });

  this._countDownSubscription.onDone(() {
    if (widget.posts.length == this._index + 1) {
      Navigator.of(context).pop();
    } else {
      if (mounted)
        setState(() {
          this._index++;
          this._initTimer();
        });
    }
  });
}

进度条：

class ProgressPainter extends CustomPainter {
  final double value;

  ProgressPainter({this.value});

  Paint backgroundPaint = Paint()
    ..color = Colors.white
    ..style = PaintingStyle.stroke
    ..strokeCap = StrokeCap.round
    ..strokeWidth = 10;

  Paint valuePaint = Paint()
    ..color = Colors.deepPurple
    ..style = PaintingStyle.stroke
    ..strokeCap = StrokeCap.round
    ..strokeWidth = 10;

  @override
  void paint(Canvas canvas, Size size) {
    Path backgroundPath = Path();
    Path valuePath = Path();

    backgroundPath.moveTo(0, size.height / 2);
    backgroundPath.lineTo(size.width, size.height / 2);

    valuePath.moveTo(0, size.height / 2);
    valuePath.lineTo(size.width * this.value, size.height / 2);

    canvas.drawPath(backgroundPath, backgroundPaint);
    canvas.drawPath(valuePath, valuePaint);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    return true;
  }
}

动态进度条数：

Row(
  mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  children: List.generate(widget.posts.length, (index) {
    if (this._index == index) { // Current active post
      return Expanded(
        child: Container(
          padding: EdgeInsets.symmetric(horizontal: 10.0),
          child: CustomPaint(
            foregroundPainter: ProgressPainter(value: this._countDown.remainingTime.inSeconds / 10.0),
          ),
        ),
      );
    } else if (this._index > index) { // when it's done
      return Expanded(
        child: Container(
          padding: EdgeInsets.symmetric(horizontal: 10.0),
          child: CustomPaint(
            foregroundPainter: ProgressPainter(value: 0.0),
          ),
        ),
      );
    } else { // When it's next
      return Expanded(
        child: Container(
          padding: EdgeInsets.symmetric(horizontal: 10.0),
          child: CustomPaint(
            foregroundPainter: ProgressPainter(value: 1.0),
          ),
        ),
      );
    }
  }).reversed.toList(),
)

如果你们有更好更简单的解决方案，我完全赞成

Row(
  mainAxisAlignment: MainAxisAlignment.spaceEvenly,
  children: List.generate(widget.posts.length, (index) {
    if (this._index == index) { // Current active post
      return Expanded(
        child: Container(
          padding: EdgeInsets.symmetric(horizontal: 10.0),
          child: CustomPaint(
            foregroundPainter: ProgressPainter(value: this._countDown.remainingTime.inSeconds / 10.0),
          ),
        ),
      );
    } else if (this._index > index) { // when it's done
      return Expanded(
        child: Container(
          padding: EdgeInsets.symmetric(horizontal: 10.0),
          child: CustomPaint(
            foregroundPainter: ProgressPainter(value: 0.0),
          ),
        ),
      );
    } else { // When it's next
      return Expanded(
        child: Container(
          padding: EdgeInsets.symmetric(horizontal: 10.0),
          child: CustomPaint(
            foregroundPainter: ProgressPainter(value: 1.0),
          ),
        ),
      );
    }
  }).reversed.toList(),
)