paint method

void paint(PaintingContext context, Offset center, { required Animation<double> activationAnimation, required Animation<double> enableAnimation, required double value, required Size size, required Offset thumbCenter, })

Implementation

void paint(PaintingContext context,
    Offset center, {
      required Animation<double> activationAnimation,
      required Animation<double> enableAnimation,
      required double value,
      required Size size,
      required Offset thumbCenter,
    }) {
  final Canvas canvas = context.canvas;

  final height = size.height;
  final enabledThumbRadius = height / 2 - RoundThumbShape.marginRingWidth;
  final disabledThumbRadius = height / 2 - RoundThumbShape.marginRingWidth;
  final Tween<double> radiusTween = Tween<double>(
    begin: disabledThumbRadius,
    end: enabledThumbRadius,
  );

  Color thumbColor = _getCurrentColor(value, gradientColors, gradientStops);

  final ColorTween thumbColorTween = ColorTween(
    begin: Color.alphaBlend(thumbColor.withOpacity(0.5), Colors.black87),
    end: thumbColor,
  );
  final ColorTween shadowColorTween = ColorTween(
    begin: Colors.transparent,
    end: Colors.black,
  );

  final Color color = thumbColorTween.evaluate(enableAnimation)!;
  final Color shadowColor = shadowColorTween.evaluate(enableAnimation)!;
  final double radius = radiusTween.evaluate(enableAnimation);

  final Tween<double> elevationTween = Tween<double>(
    begin: elevation,
    end: pressedElevation,
  );

  final double evaluatedElevation = elevationTween.evaluate(activationAnimation);
  final Path path = Path()
    ..addArc(Rect.fromCenter(center: center, width: 2 * radius, height: 2 * radius), 0, math.pi * 2);
  canvas.drawShadow(path, shadowColor, evaluatedElevation, true);

  canvas.drawCircle(
    center,
    (radius - marginRingWidth * (1 - activationAnimation.value)),
    Paint()
      ..color = Colors.white
      ..style = PaintingStyle.stroke
      ..isAntiAlias = true
      ..strokeWidth = marginRingWidth,
  );

  canvas.drawCircle(center, radius + evaluatedElevation - 2 * marginRingWidth, Paint()
    ..color = color);
}