如何在Flutter中延迟几秒后持续地在画布上绘制？

Question

我有一组已定义的偏移量。我只想在延迟后在画布上绘制这些偏移量，以向用户展示绘图进度。我该如何实现相同的效果？以下是我的代码。但它会在drawPath行报错，提示“对象已被处理”。

class ReplayPainter extends CustomPainter {
  List<PathData> strokes = new List<PathData>();

  ReplayPainter(this.strokes);

  @override
  void paint(Canvas canvas, Size size) {
    print(strokes.length);
    for (PathData stroke in strokes) {
      Paint strokePaint = new Paint();
      strokePaint.strokeWidth = stroke.strokeWidth;
      strokePaint.style = PaintingStyle.stroke;
      strokePaint.strokeJoin = StrokeJoin.round;
      strokePaint.strokeCap = StrokeCap.round;
      strokePaint.color = stroke.strokeColor;

      Path strokePath = new Path();
      strokePath.addPolygon(stroke.offsets, false);
      Timer _timer = new Timer(const Duration(milliseconds: 100), () {
        canvas.drawPath(strokePath, strokePaint);
      });
    }
  }

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

}

路径数据中包含偏移量，请帮忙。

- user983327

Answer 1

必须使用AnimationController。在阅读下面的两个部分教程后，我成功完成了它。

https://medium.com/flutter-io/zero-to-one-with-flutter-43b13fd7b354

https://medium.com/flutter-io/zero-to-one-with-flutter-part-two-5aa2f06655cb

- user983327