draw method

Implementation

@override
void draw(
  Canvas canvas,
  Size size,
  DrafterThemeColors theme,
  double progress,
) {
  if (points.length < 2) return;
  final values = [for (final p in points) drafterFinite(p.value)];

  final scale = _scaleFor(size);
  final bounds = scale.bounds;
  final maxValue = scale.maxValue;

  // Y grid + labels (4 ticks).
  const tickCount = 4;
  final gridPaint = Paint()
    ..color = theme.grid
    ..style = PaintingStyle.stroke
    ..strokeWidth = 1;
  for (var i = 0; i <= tickCount; i++) {
    final frac = i / tickCount;
    final y = bounds.bottom - frac * bounds.height;
    canvas.drawLine(
      Offset(bounds.left, y),
      Offset(bounds.right, y),
      gridPaint,
    );

    final tickValue = maxValue * frac;
    drawChartText(
      canvas,
      ChartFormatting.format(tickValue),
      Offset(bounds.left - 6, y),
      color: theme.label,
      h: HAlign.end,
      v: VAlign.center,
    );
  }

  // Map points into pixel space via the shared scale.
  final pixelPoints = <Offset>[
    for (var index = 0; index < values.length; index++)
      Offset(scale.xForIndex(index), scale.yForValue(values[index])),
  ];

  // Smooth area + line + reveal + end dot (shared helper).
  drawSmoothLine(
    canvas,
    points: pixelPoints,
    color: color,
    baseline: bounds.bottom,
    progress: progress,
    strokeWidth: 5,
  );

  // Vertex dots, revealed alongside the trace.
  final revealRight = bounds.left + bounds.width * progress.clamp(0.0, 1.0);
  for (final point in pixelPoints) {
    if (point.dx <= revealRight + 0.5) {
      drawVertexDot(canvas, point, color, 4);
    }
  }

  // X labels, thinned so they stay legible at small sizes (at most ~6). Each
  // label travels with its point, so labels can never shift or run short.
  const maxLabels = 6;
  final labelStride = math.max(
    1,
    (pixelPoints.length + maxLabels - 1) ~/ maxLabels,
  );
  for (var index = 0; index < pixelPoints.length; index++) {
    if (index % labelStride != 0) continue;
    final label = points[index].label;
    if (label.isEmpty) continue;
    drawChartText(
      canvas,
      label,
      Offset(pixelPoints[index].dx, bounds.bottom + 13),
      color: theme.label,
      h: HAlign.center,
      v: VAlign.center,
    );
  }
}