paint method

@override void paint(Canvas canvas, Size size, WorldToScreen worldToScreen, ScreenToWorld screenToWorld, double scale,)

Called by the canvas to paint this item onto the screen.

The canvas and size are provided by the Flutter framework. Use worldToScreen to translate mathematical coordinates into on-screen pixels.

Implementation

@override
void paint(
  Canvas canvas,
  Size size,
  WorldToScreen worldToScreen,
  ScreenToWorld screenToWorld,
  double scale,
) {
  if (points.isEmpty) return;

  final screenPoints = points.map((p) => worldToScreen(p.x, p.y)).toList();

  if (connectPoints && screenPoints.length > 1) {
    final path = Path()..moveTo(screenPoints[0].dx, screenPoints[0].dy);
    for (int i = 1; i < screenPoints.length; i++) {
      path.lineTo(screenPoints[i].dx, screenPoints[i].dy);
    }

    canvas.drawPath(
      path.shift(const Offset(0, 2)),
      Paint()
        ..color = color.withOpacity(0.2)
        ..strokeWidth = lineWidth
        ..style = PaintingStyle.stroke
        ..strokeCap = lineCap
        ..strokeJoin = StrokeJoin.round
        ..maskFilter = const MaskFilter.blur(BlurStyle.normal, 2.0),
    );

    canvas.drawPath(
      path,
      Paint()
        ..color = color
        ..strokeWidth = lineWidth
        ..style = PaintingStyle.stroke
        ..strokeCap = lineCap
        ..strokeJoin = StrokeJoin.round,
    );
  }

  if (showPoints) {
    for (int i = 0; i < points.length; i++) {
      final currentPoint = points[i];
      final currentScreenPoint = screenPoints[i];
      final currentRadius = currentPoint.radius ?? pointRadius;
      final currentColor = currentPoint.color ?? color;

      canvas.drawCircle(
        currentScreenPoint,
        currentRadius,
        Paint()..color = currentColor,
      );
      canvas.drawCircle(
        currentScreenPoint,
        currentRadius,
        Paint()
          ..color = Colors.white
          ..style = PaintingStyle.stroke
          ..strokeWidth = 1.2,
      );

      if (currentPoint.label != null) {
        final textPainter = TextPainter(
          text: TextSpan(
            text: currentPoint.label,
            style: TextStyle(
              fontSize: 11,
              color: currentColor,
              fontWeight: FontWeight.w600,
            ),
          ),
          textDirection: TextDirection.ltr,
        )..layout();
        textPainter.paint(canvas, currentScreenPoint + const Offset(8, -14));
      }
    }
  }
}