animated-donut-chart-05

donut-chart-painter.dart

  TextPainter measureText(
      String s, TextStyle style, double maxWidth, TextAlign align) {
    final span = TextSpan(text: s, style: style);
    final tp = TextPainter(
        text: span, textAlign: align, textDirection: TextDirection.ltr);
    // ellipsis: "...");
    tp.layout(minWidth: 0, maxWidth: maxWidth);
    return tp;
  }

  Size drawTextCentered(Canvas canvas, Offset position, String text,
      TextStyle style, double maxWidth, Function(Size sz) bgCb) {
    final tp = measureText(text, style, maxWidth, TextAlign.center);
    final pos = position + Offset(-tp.width / 2.0, -tp.height / 2.0);
    bgCb(tp.size);
    tp.paint(canvas, pos);
    return tp.size;
  }