render method

@override void render(Canvas canvas)

Implementation

@override
void render(Canvas canvas) {
  if (!visible) return;

  // Dim track — full width strip at screen top
  canvas.drawRect(
    size.toRect(),
    Paint()..color = const Color(0x33FFFFFF),
  );

  if (fillAmount <= 0) return;

  final fillW = size.x * fillAmount;

  // Gradient fill: green → yellow → red mapped to the full track width
  final shader = LinearGradient(
    colors: _gradientColors,
    stops: const [0.0, 0.5, 1.0],
  ).createShader(Rect.fromLTWH(0, 0, size.x, size.y));

  canvas.drawRect(
    Rect.fromLTWH(0, 0, fillW, size.y),
    Paint()..shader = shader,
  );

  // Glow bloom when power is high
  if (fillAmount > 0.6) {
    final t = ((fillAmount - 0.6) / 0.4).clamp(0.0, 1.0);
    canvas.drawRect(
      Rect.fromLTWH(0, 0, fillW, size.y),
      Paint()
        ..color = const Color(0xFFF44336).withValues(alpha: 0.45 * t)
        ..maskFilter = const MaskFilter.blur(BlurStyle.normal, 7),
    );
  }

  // White needle at fill edge for precise timing feedback
  if (fillAmount > 0.015 && fillAmount < 0.99) {
    canvas.drawLine(
      Offset(fillW, 0),
      Offset(fillW, size.y),
      Paint()
        ..color = Colors.white.withValues(alpha: 0.95)
        ..strokeWidth = 2.0,
    );
  }
}